Evidence Tables

Cook D, Meade M, Guyatt G, et al. Criteria for Weaning from Mechanical Ventilation. Rockville (MD): Agency for Healthcare Research and Quality (US); 2000 Nov. (Evidence Reports/Technology Assessments, No. 23.) Evidence Tables.

Evidence Table 1. General characteristics of all studies

Characteristics	Number of Studies
*Number of studies first* identified from each source**
Medline	119
CINAHL	13
EMBASE	10
Citation Lists	6
HealthSTAR	1
Author contact	1
Cochrane RCT Registry	0
Year of publication
1971-75	2
1976-80	7
1981-85	4
1986-90	16
1991-95	47
1996-99	74
Other	0
Language of publication
English	143
Non-English	7
Source of funding ¹
Professional Organization	20
Government Agency	17
Other	9
Industry	4
Charity	2
Consumer Organization	0
Unclear	6
Not reported	99
Number of studies investigating each AHRQ research question ²
When should weaning be initiated?	31
What criteria should be used to initiate the weaning process?	34
What are the most effective methods of weaning from mechanical ventilation?	120
What is the value of clinical practice algorithms and computers in expeditious weaning?	16
What are the optimal roles of nonphysician health care professionals in facilitating safe and expeditious weaning?	18

1: More than one source of funding may apply to each study

2: Individual studies may address one or more of the AHRQ research questions

Evidence Table 2. Population characteristics for all studies

Characteristics	Number of Studies
Health care setting
Tertiary care hospital (university/teaching hospital )	131
Community hospital	8
Long term ventilatory care facility	1
Other	10
Type of intensive care unit(s) ¹
Medical	51
Surgical	40
Cardiovascular	24
Trauma	6
Coronary care	3
Other	61
Country in which study was centered
USA	79
Canada	15
France	12
Spain	9
Great Britain	6
Japan	4
Australia	3
Germany	3
Italy	3
Taiwan	3
South Africa	2
Switzerland	2
Argentina	1
Belgium	1
Chile	1
Finland	1
Greece	1
Hong Kong	1
India	1
Netherlands	1
Russia	1
Singapore	1
Sweden	1
Turkey	1
Number of participating hospitals
1	125
2	7
3	4
8	1
14	1
30	1
Unclear	6
Not reported	5
Number of participating intensive care units
1	108
2	10
3	3
>4	6
Unclear	14
Not reported	9
Population age group ²
Adult	134
Paediatric	13
Elderly only	4
Neonatal mixed with pediatric	0
Diagnostic categories of patients ³
COPD	63
Asthma	19
Pneumonia	51
CHF	41
Acute lung injury	22
Hemodynamic instability	19
Post-operative	57
Neuromuscular	16
Neurological	43
Airway protection	10
Coronary artery bypass surgery	53
Cardiac valvular surger	31
Congenital heart disease	7
Infant respiratory distress syndrome	3
Trauma	33
Other	79
Unclear	2
Not reported	7

1: More than one ICU type may apply per study.

2: More than one population age may apply per study.

3: More than one diagnostic category may apply per study.

Evidence Table 3. Design characteristics for all studies

Characteristics	No. of Studies
Study design
RCT, parallel	45
RCT, crossover	1
Non-RCT, contemporaneous controls	5
Non-RCT, historical controls	18
Case series	74
Review Article	0
Unclear	0
Other	7
Direction of investigation
Prospective	129
Retrospective	20
Unclear	1
Not reported	0

Evidence Table 4. Interventions characteristics for all studies

Characteristics	Number of Studies
Point of initiation of intervention ¹
Time of intubation	18
Specified duration of mechanical ventilation	15
"Ready to wean" by time criteria	4
"Ready to wean" by vital signs criteria	30
"Ready to wean" by lung mechanics criteria	36
"Ready to wean" by gas exchange criteria	37
"Ready to wean" by scores/composite measures criteria	1
"Ready to wean" clinical impression	48
Failed wean	13
"Possibly ready to extubate" by time criteria	0
"Possibly ready to extubate" by vital signs criteria	9
"Possibly ready to extubate" by lung mechanics criteria	8
"Possibly ready to extubate" by gas exchange criteria	17
"Possibly ready to extubate" by scores/composite measures criteria	1
"Possibly ready to extubate" clinical impression	22
Failed extubation	11
Successful extubation	9
Unclear	7
Not reported	2
Type of intervention
Weaning criteria	40
Weaning protocol - general	19
Weaning protocol - computerized	3
Weaning mode of ventilation	17
Weaning technology	3
Noninvasive ventilation for weaning purposes	4
Tracheostomy - present or absent	0
Tracheostomy - variable timing	0
Extubation criteria	20
Extubation - variable timing	11
Drug intervention	21
Other	12

1: More than one point of initiation of intervention may apply per study

Evidence Table 5. Characteristics of included randomized clinical trials

Characteristics	Number of Studies
Method of randomization
Randomization table (+/-computer generated)	17
Coin flip	1
Alternating treatment allocation	0
Not clearly reported	19
Not reported at all	7
Concealment of allocation
Not concealed	0
Concealed by independent randomization center	0
Concealed by sealed opaque envelopes	6
Sealed unspecified envelopes	5
Unclear	1
Not reported	32
Blinding
RT blinded	1
RT not blinded	6
RT blinding unclear	2
RT blinding not reported	35
Nurses blinded	2
Nurses not blinded	6
Nursing blinding unclear	2
Nursing blinding not reported	34
Physicians blinded	6
Physicians not blinded	7
Physician blinding unclear	1
Physician blinding not report	30
Reasons for study withdrawals reported for each arm
Yes	17
No	1
Unclear	1
Probably no withdrawals	25
Interventions	No. of Studies
Studies Comparing Alternative Discontinuation Assessment Strategies
1. T-piece	6
2. T-piece trial 30 minutes	1
3. T-piece trial 120 minutes	1
4. CPAP 5 (or 4)	5
5. CPAP 10	1
6. PS 7	1
7. IMV 4 and CPAP 5	2
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support
8. PS (to maintain minute volume)	2
9. IMV (to maintain minute volume)	1
10. Carbon dioxide mandatory ventilation	1
11. Noninvasive ventilation	2
12. Controlled ventilation	1
Studies Comparing Alternative Ventilation Modes for Weans Lasting Less than 48 Hours
13. Extubation + NPPV	0
14. PS	6
15. SIMV	4
16. Multiple daily T-piece trials	2
17. Once daily T-piece trial	1
18. SIMV + PS	1
19. IMV	2
20. MMV	1
Studies Comparing Weaning Protocols with Physician Directed Weaning
21. Protocol by nurse and RT	1
22. Physician directed weaning	3
23. Daily screening +/-T-piece trial	1
24. Computer-directed weaning	1
Studies Comparing Early vs Late Extubation Following Cardiac Surgery
25. Early	11
26. Late	11
Studies Evaluating Steroids to Prevent Postextubation Airway Complications
27. Steroids	7
28. No steroids	7
Studies of Enteral Nutrition
29. High fat-low carbohydrate feeds	2
30. Isocaloric feeds	2
Miscellaneous Interventions
31. Nasal BiPAP	2
32. CPAP	1
33. Routine chest physiotherapy	2
34. Recombinant growth hormone	1
35. No recombinant growth hormone	1
36. Pulse oximetry and capnography	1
37. Periodic ABG	1
38. Relaxation biofeedback	1
39. No relaxation biofeedback	1
40. Tactile/verbal stimulation from nurse	1
41. No tactile/verbal stimulation from nurse	1
42. BiPAP/APRV wean	1
43. Acupuncture	1
44. PSV wean	1
Outcome Measurements	No. of Studies
Major Outcomes
1. ICU mortality	6
2. Hospital mortality	8
3. 30-day mortality	2
4. 60-day mortality	1
5. 90-day mortality	1
6. Reintubation rate	27
7. Extubation rate	15
8. Nonextubation rate at various times	2
9. Self-extubation	1
10. Successful T-piece trial	1
11. ICU length of stay	14
12. ICU discharge at 24 or 48 h	1
13. Hospital length of stay	11
14. Duration of mechanical ventilation	18
15. Duration of mechanical ventilation per day	1
16. Duration of weaning	8
17. Duration of weaning per day	1
18. Duration of successful wean	1
19. No. of patients requiring mechanical ventilation >7 days	1
20. Mechanical ventilation for >21 days	2
21. Successful weaning at day 12	1
22. Composite outcome: failed weaning = death or reintubation	1
23. Duration of intubation	3
Minor Outcomes
24. Tidal volume	1
25. Change in tidal volume	1
26. Respiratory rate	2
27. Change in respiratory rate	2
28. Vital capacity	1
29. Maximal inspiratory pressure at weaning termination	1
30. Arterial partial pressure of carbon dioxide (PaCO₂)	1
31. Change in PaCO₂	1
32. Stridor score	1
33. Postextubation stridor	2
34. Postextubation stridor at 10 min	1
35. Postextubation stridor at 6 h	1
36. Postextubation at 12 h	1
37. Postextubation stridor 24 h	1
38. Laryngospasm	1
39. Croup score at 10 min following extubation	1
40. Croup score at 6 hours following extubation	1
41. Croup score at 12 hours following extubation	1
Outcome Measurements	No. of Studies
Minor Outcomes
42. Croup score at 24 hours following extubation	1
43. Postextubation use of racemic epinephrine	1
44. Laryngeal lesions related to airway	2
45. Number of arterial blood gas samples	2
46. Tracheostomy	1
47. Mean peak serum CPK level	1
48. Serum CPK level at 24 hours	2
49. Serum CPK level at 36 hours	1
50. Serum CPK level at 48 hours	1
51. Total myocardial infarction whether fatal or nonfatal	8
52. Arrhythmias	7
53. Ischemia incidence at 24 hours	1
54. Ischemia incidence at 48 hours	1
55. Ischemia: area under the curve	1
56. Duration of ischemia	1
57. Maximum ST depression	1
58. Proportion of patients with ischemia; ischemic burden	2
59. Number of patients with ischemia	3
60. Incidence of angina	1
61. Incidence of pulmonary edema, ischemic heart failure	2
62. Pulmonary arterial pressure	1
63. Pulmonary capillary wedge pressure	1
64. Pulmonary vascular resistance index	1
65. Right ventricular ejection fraction at time 1	1
66. Cardiac index after extubation	1
67. Cardiac index 60 minutes following extubation	2
68. Cardiac index 90 minutes following extubation	1
69. Mean arterial pressure	1
70. Pulmonary blood volume index at extubation	1
71. Pulmonary blood volume index 60 minutes after extubation	1
72. Pulmonary blood volume index 90 minutes after extubation	1
73. Extravascular lung water at extubation	1
74. Extravascular lung water at 60 minutes after extubation	1
75. Extravascular lung water at 90 minutes after extubation	1
76. Nosocomial pneumonia	4
77. Nasal abrasion	1
78. Respiratory quotient	1
79. Spontaneous breathing for 3 hours	1
Outcome Measurements	No. of Studies
Minor Outcomes
80. minute ventilation during weaning	2
81. cumulative duration of mechanical support over 12-day study period	1
82. right ventricular end systolic volume (RVESV)	1
83. right ventricular end diastolic volume (RVEDV)	1
84. need to resume controlled ventilation	2
85. change in PaCO₂	1
86. change In PaO₂	1
87. time on ventilator from commencement of feeding to successful	1
88. change in alveolar-arterial oxygen difference (AaDO₂)	1
89. change in vital capacity	1
90. change in maximal inspiratory pressure	1

Evidence Table 6. Methodologic characteristics of randomized trials, grouped according to intervention type

Studies Comparing Alternative Discontinuation Assessment Strategies
Author (year)	ICU Population	Diagnoses	Method of Randomization	Concealment	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Feeley (1975)	25 patients in acute respiratory failure in a medical-surgical ICU	COPD, pneumonia, post-op, cardiac bypass surgery, cardiac valve surgery, infant RDS	Not reported	Not reported	Yes	Yes	No
Hastings (1980)	18 good-risk, stable cardiac surgery patients in a CVICU	Cardiac bypass surgery, cardiac valve surgery	Not clearly reported	Not reported	Yes	No	No
Jones (1991)	106 patients in a medical, surgical ICU in a tertiary care hospital	COPD, asthma, pneumonia, CHF, neurological, post-op, airway protection	Not clearly reported	Sealed unspecified envelopes	No	Yes	No
Abalos (1992)	62 high-risk postoperative patients undergoing weaning in a surgical ICU in a tertiary care hospital	Post-op, unclear	Not reported	Not reported	No	No	No
Schirmer (1994)	22 patients following coronary artery bypass grafting in a CVICU in a tertiary care hospital	Cardiac bypass surgery	Not reported	Not reported	Yes	No	No
Bailey (1995)	80 adult patients scheduled to undergo primary aortocoronary bypass in a CVICU	Cardiac bypass surgery	Randomization table	Not reported	Yes	Yes	No
Esteban (1997)	484 patients in a medical, surgical, ICU in a tertiary care hospital	COPD, pneumonia, CHF, acute lung injury, neurological, post-op, neuromuscular, trauma	Randomization table	Sealed opaque envelopes	Yes	Yes	Yes
Esteban (1999)	526 patients in a medical and surgical ICU in a tertiary care hospital	COPD, pneumonia, CHF, acute lung injury, post-op, neuromuscular, trauma	Randomization table	Sealed opaque envelopes	Yes	Yes	Yes
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support
Author (year)	ICU Population	Diagnoses	Method of Randomization	Concealment	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Brochard (1994)	109 patients ventilated >24 hours and recovered from the acute phase of their disease in a medical-surgical ICU	COPD, CHF, post-op, neurological, neuromuscular	Not clearly reported	Sealed envelopes	Yes	Yes	No
Jounieaux (1994)	19 COPD patients requiring mechanical ventilation for acute respiratory failure in a medical ICU	COPD	Not reported	Not reported	Yes	Yes	No
Esteban (1995)	130 patients in a medical, surgical ICU in a tertiary care hospital	COPD, pneumonia, CHF, acute lung injury, post-op, neurological, neuromuscular, trauma	Randomization table	Sealed opaque envelopes	Yes	Yes	No
Nava (1998)	50 intubated patients in a respiratory ICU	COPD	Not clearly reported	Sealed opaque envelopes	No	Yes	Yes
Girault (1999)	33 patients in a medical ICU in a tertiary care hospital	COPD	Not clearly reported	Not reported	Yes	Yes	No
Studies Comparing Alternative Ventilation Modes for Weans Lasting Less than 48 Hours
Chopin (1989)	42 adult patients with >4 days of controlled ventilation in a medical ICU	COPD	Randomization table	Not reported	Yes	Yes	No
Davis (1989)	40 patients with > 24 hours of ventilation in a medical ICU	COPD, pneumonia	Not reported at all	Not reported	Yes	No	No
Esen (1992)	40 mechanically ventilated patients with thorax injury in a trauma ICU in a tertiary care hospital	Trauma	Randomization method not clearly reported	Not reported	Yes	No	No
Studies Comparing Weaning Protocols to Physician-Directed Weaning
Strickland (1993)	15 patients with complex medical problems who had required prolonged mechanical ventilation in medical ICU in a tertiary care hospital	COPD, asthma, pneumonia, CHF, acute lung injury, hemodynamic instability, neurological, post-op, cardiac valve surgery, trauma	Randomization table	Sealed unspecified envelopes	Yes	No	No
Ely (1996)	300 patients in a medical ICU, CCU in a tertiary care hospital	COPD, asthma, pneumonia, CHF, neurological, acute lung injury	Randomization table	Concealed by sealed opaque envelopes	Yes	No	No
Kollef (1997)	357 patients requiring mechanical ventilation in a medical, surgical ICU in a tertiary care hospital	COPD, asthma, pneumonia, acute lung injury, hemodynamic instability, post-op, trauma	Coin flip	Sealed opaque envelopes	Yes	Yes	No
Studies Comparing Early vs Late Extubation Follwing Cardiac Surgery (Anesthesia Intervention)
Author (year)	ICU Population	Diagnoses	Method of Randomization	Concealment	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Cheng (1996)	120 elective coronary artery bypass grafting patients	Cardiac bypass	Randomization table	Not reported	No	Yes	No
Berry (1998)	98 patients with elective coronary artery bypass grafting	Cardiac bypass	Randomization table	Not reported	No	Yes	No
Michalopoulos (1998)	144 patients with elective coronary artery bypass grafting	Cardiac bypass	Not clearly reported	Not reported	No	Yes	No
Silbert (1998)	100 patients with elective coronary artery bypass grafting	Cardiac bypass	Randomization table	Unclear	Yes	No	No
Engoren (1998)	70 patients in a CVICU in a tertiary care hospital	Cardiac bypass	Randomization table	Not reported	Yes	Yes	No
Studies Comparing Early vs Late Extubation Following Cardiac Surgery (ICU Intervention)
Quasha (1980)	38 patients with coronary artery bypass grafting	Cardiac bypass	Not reported	Not reported	Yes	Yes	No
Shackford (1981)	35 patients undergoing aortic reconstruction in a tertiary care ICU	Aortic reconstruction	Not clearly reported	Not reported	No	Yes	No
Tempe (1995)	100 patients undergoing elective closed mitral valvotomy	Mitral valve surgery	Not clearly reported	Not reported	Yes	Yes	No
Reyes (1997)	404 open heart surgery patients	COPD, CHF, cardiac bypass surgery, cardiac valve surgery	Randomization table	Not reported	Yes	Yes	Yes
Dumas (1999)	47 patients in a CVICU in a tertiary care hospital	Hemodynamic instability, cardiac bypass surgery	Not clearly reported	Not reported	No	Yes	No
Pediatric Studies of Corticosteroids to Prevent Postextubation Airway Complications
Author (year)	ICU Population	Diagnoses	Method of Randomization	Concealment	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Tellez (1991)	153 patients requiring airway stabilization and mechanical ventilation in a pediatric ICU in a children's hospital	Asthma, cardiac bypass surgery, trauma	Not clearly reported	Not reported	No	No	No
Anene (1996)	66 children <5 years, intubated and mechanically ventilated for >48 hours, in a tertiary care pediatric ICU	Pneumonia, post-op, neurological, congenital heart disease	Randomization table	Not reported	No	Yes	Yes
Harel (1997)	26 tertiary care, pediatric ICU patients who had failed extubation with postextubation stridor	Asthma, pneumonia, acute lung injury, post-operative, neurological, infant RDS, trauma	Not clearly reported	Sealed envelopes	No	No	No
Adult Studies of Corticosteroids to Prevent Postextubation Airway Complications
Gaussorgues (1987)	276 mechanically ventilated patients in an ICU	Pneumonia, hemodynamic instability, post-op, neurological	Not reported	Not reported	No	No	No
Darmon (1992)	700 patients >15 years who had undergone tracheal intubation in an ICU	Hemodynamic instability, neurological, post-op	Randomization table	Sealed envelopes	No	No	No
Ho (1996)	77 patients >14 years of age, who had undergone tracheal intubation for more than 24 hours in a tertiary care medical-surgical ICU	Hemodynamic instability, post-op, neurological, trauma	Randomization table	Not reported	No	No	No
Chaney (1998)	60 patients in a CVICU in a tertiary care hospital	Cardiac bypass surgery	Not clearly reported	Not reported	No	Yes	No
Studies of Enteral Nutrition
Author (year)	ICU Population	Diagnoses	Method of Randomization	Concealment	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
al-Saady (1989)	20 patients in a setting that was not described	COPD, pneumonia, acute lung injury, hemodynamic instability, post-op, trauma	Not clearly reported	Not reported	Yes	Yes	No
Vandenberg (1994)	32 adult, ventilator- dependent patients in a tertiary care medical ICU	COPD, pneumonia, neurological	Randomization table	Not reported	Yes	No	No
Miscellaneous Studies
Niehoff (1988)	24 mechanically ventilated patients in a tertiary care surgical ICU	Cardiac bypass surgery, cardiac valve surgery	Not clearly reported	Not reported	Yes	No	No
Holliday (1990)	40 patients in a medical surgical CVICU	COPD, pneumonia, hemodynamic instability, post-op, neurological, cardiac bypass surgery, trauma	Randomization table	Not reported	No	No	No
Gust (1996)	75 patients following coronary artery bypass grafting in a CVICU in a tertiary care hospital	Cardiac bypass surgery	Not clearly reported	Not reported	Yes	No	No
Pichard (1996)	20 patients requiring 7 days of mechanical ventilation for acute respiratory failure in setting that was not described	COPD, pneumonia, acute lung injury, trauma	Not clearly reported	Not reported	Yes	Yes	No
Jiang (1999)	93 patients in a tertiary care hospital	COPD, CHF, neurological	Not clearly reported	Not reported	No	Yes	Yes
Lee (1998)	76 patients in a post-anesthesia recovery room in a tertiary care hospital	postoperative	Not clearly reported	Not reported	No	Yes	No

Evidence Table 7. Results of individual randomized trials

Studies Comparing Alternative Discontinuation Assessment Strategies
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Feeley (1975) int 1: CPAP 5 cm H₂O int 2: T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Change in PaCO₂ Duration of Weaning Change in AaDO₂ Change in Vital Capacity Change in MIP	1: 9.38 ± 8.80 2: 8.69 ± 5.34 1: 31.43 ± 68.30 2: 5.20 ± 4.27 1: 10.00 ± 76.21 2: 102.00 ± 126.19 1: 258.00 ± 374.12 2: -8.00 ± 198.31 1: -15.00 ± 17.32 2: -1.00 ± 10.82	0.69 (-4.96, 6.34) 26.23 (-10.73, 63.19) -92.00 (-174.62, -9.38) 266.00 (33.96, 498.04) -14.00 (-25.22, -2.78)	0.81 0.16 0.03 0.02 0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Nonextubation Reintubation Combined Endpoint: Nonextubation + Reintubation	1: 2/12 2: 1/13 1: 4/12 2: 2/13 1: 1/8 2: 0/11 1: 5/12 2: 2/13	1.80 (0.28, 11.71) 1.94 (0.51, 7.43) 4.06 (0.19, 87.91) 2.38 (0.66, 8.56)	0.54 0.33 0.37 0.19
Hastings (1980) int 1: IMV 4 bpm Plus CPAP 5 cm H₂O int 2: CPAP 5 cm H₂O	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation Duration of Weaning	1: 28.32 ± 3.18 2: 24.40 ± 7.18 1: 2.82 ± 1.10 2: 2.50 ± 1.15	3.92 (-1.45, 9.29) 0.32 (-0.73, 1.37)	0.15 0.55
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 0/8 2: 0/10	1.00	1.00
Jones (1991) int 1: CPAP 5 cm H₂O int 2: T-Piece	Binary Variables	Proportion with Event	Relative Risk (95% CI)
Jones (1991) int 1: CPAP 5 cm H₂O int 2: T-Piece	Nonextubation Reintubation Combined Endpoint: Nonextubation + Reintubation	1: 3/54 2: 2/52 1: 3/51 2: 2/50 1: 6/54 2: 4/52	1.35 (0.28, 6.54) 1.37 (0.28, 6.64) 1.39 (0.44, 4.35)	0.71 0.69 0.57
Abalos (1992) int 1: CPAP 10 cm H₂O int 2: CPAP 5 cm H₂O int 3: T-Piece	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Cardiac Ischemia	1: 0/19 2: 2/22 3: 3/21	1 vs. 3: 0.16 (0.01, 2.86) 2 vs. 3: 0.68 (0.15, 3.09) 1 vs. 2: 0.23 (0.01, 4.52)	0.21 0.62 0.33
Schirmer (1994) int 1: PS10 cm H₂O + PEEP 5 cm H₂O (I:E = 1:2 using BiPAP System) int 2: PS10 + PEEP5 (I:E Variable)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Right Ventricular End Systolic Volume Right Ventricular End Diastolic Volume Tidal Volume Respiratory Rate PaO₂ PaCO₂ Mean Pulmonary Arterial Pressure Pulmonary Capillary Wedge Pressure Pulmonary Vascular Resistance Index Right Ventricular Ejection Fraction Cardiac Index Mean Arterial Pressure	1: 92.20 ± 36.30 2: 77.20 ± 30.40 1: 176.00 ±48.50 2: 161.60 ± 43.30 1: 550.00 ±155.00 2: 615.00 ± 160.00 1: 13.80 ± 2.80 2: 13.80 ± 8.10 1: 97.60 ± 14.60 2: 97.80 ± 17.10 1: 41.70 ± 3.20 2: 41.90 ± 3.20 1: 20.60 ± 5.00 2: 19.30 ± 4.20 1: 12.20 ± 3.90 2: 12.10 ± 3.90 1: 206.00 ± 55.00 2: 181.00 ± 61.00 1: 46.00 ± 11.90 2: 51.80 ± 12.40 1: 3.10 ± 0.70 2: 3.40 ± 0.80 1: 76.30 ± 11.60 2: 74.60 ± 10.10	15.00 14.80 -65.00 0.00 -0.20 -0.20 1.30 (0.21, 2.39) 0.10 25.00 (1.10, 48.90) -5.80 (-9.26, -2.34) -0.30 1.70	>0.05 >0.05 >0.05 >0.05 >0.05 >0.05 0.02 >0.05 0.04 0.001 >0.05 >0.05
Bailey (1995) int 1: CPAP 10 cm H₂O int 2: CPAP 5 cm H₂O int 3: T-Piece	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation	1: 0/26 2: 0/27 3: 0/27	1 vs. 3: 1.00 2 vs. 3: 1:00 1 vs. 2: 1:00	1.00 1.00 1.00
Esteban (1997) int 1: Pressure Support 7 cm H₂O int 2: T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay Hospital Length of Stay	1: 12.0 ± xx ¹ 2: 10.0 ± xx 1: 28.0 ± xx 2: 24.0 ± xx	2.00 4.00	0.33 0.33
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Hospital Mortality Nonextubation Reintubation Combined Endpoint: Nonextubation + Reintubation	1: 12/205 2: 17/192 1: 41/238 2: 40/246 1: 33/238 2: 54/246 1: 38/205 2: 36/192 1: 71/238 2: 90/246	0.67 (0.33, 1.35) 1.06 (0.71, 1.57) 0.64 (0.43, 0.94) 0.99 (0.66, 1.49) 0.89 (0.67, 1.20)	0.26 0.78 0.02 0.95 0.45
Esteban (1999) int 1: T-Piece (30 minutes) int 2: T-Piece (120 minutes)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay Hospital Length of Stay	1: 10.00 ± 9.00 2: 12.00 ± 10.50 1: 22.00 ± 13.50 2: 27.00 ± 19.50	-2.00 (-3.67, -0.33) -5.00 (-7.85, -2.15)	0.02 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Hospital Mortality Nonextubation Reintubation Combined Endpoint: Nonextubation + Reintubation	1: 34/270 2: 22/256 1: 51/270 2: 40/256 1: 33/270 2: 40/256 1: 32/237 2: 29/216 1: 65/270 2: 69/256	1.45 (0.88, 2.40) 1.21 (0.83, 1.75) 0.78 (0.51, 1.20) 1.08 (0.63, 1.60) 0.89 (0.67, 1.20)	0.14 0.33 0.26 0.99 0.45
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Brochard (1994) int 1: Pressure Support (± CPAP) int 2: Synchonized IMV (± CPAP) int 3: Multiple Daily T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Weaning (h)	1: 17.50 ± 10.20 2: 26.80 ± 19.00 3: 28.90 ± 17.70 1: 136.80 ± 88.80 2: 237.60 ± 196.80 3: 204.00 ± 199.20	1 vs. 3: -11.40 (-18.73, -4.07) 2 vs. 3: -2.10 (-10.51, 6.31) 1 vs. 2: -9.30 (-16.88, -1.72) 1 vs. 3: -67.20 (-143.29, 8.89) 2 vs. 3: 33.60 (-54.69, 121.89) 1 vs. 2: -100.80 (-175.09, -26.51)	<0.01 0.62 0.02 0.08 0.46 0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU mortality Reintubation at 48 h Nonextubation at 21 d Pulmonary Edema or Ischemic Heart Failure Nosocomial Pneumonia Combined Endpoint: Nonextubation + Reintubation	1: 4/31 2: 10/43 3: 8/35 1: 3/27 2: 6/31 3: 3/23 1: 4/31 2: 12/43 3: 12/35 1: 1/31 2: 3/43 3: 1/35 1: 0/31 2: 3/43 3: 3/35 1: 7/31 2: 18/43 3: 15/35	1 vs. 3: 0.60 (0.21, 1.68) 2 vs. 3: 1.01 (0.46, 2.22) 1 vs. 2: 0.59 (0.22, 1.62) 1 vs. 3: 0.85 (0.22, 3.68) 2 vs. 3: 1.39 (0.42, 4.53) 1 vs. 2: 0.62 (0.19, 204) 1 vs. 3: 0.41 (0.15, 1.06) 2 vs. 3: 0.82 (0.43, 1.56) 1 vs. 2: 0.50 (0.19, 1.32) 1 vs. 3: 1.13 (0.12, 10.29) 2 vs. 3: 1.90 (0.30, 12.24) 1 vs. 2: 0.59 (0.09, 3.79) 1 vs. 3: 0.16 (0.01, 3.00) 2 vs. 3: 0.82 (0.20, 3.36) 1 vs. 2: 0.20 (0.01, 3.69) 1 vs. 3: 0.55 (0.26, 1.13) 2 vs. 3: 0.97 (0.59, 1.62) 1 vs. 2: 0.56 (0.27, 1.14)	0.33 0.98 0.31 0.82 0.59 0.43 0.07 1.54 0.16 0.92 0.50 0.58 0.22 0.78 0.28 0.10 0.92 0.11
Jounieaux (1994) int 1: Synchronized IMV + Pressure Support (No CPAP) int 2: Synchronized IMV (No CPAP)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Weaning (h)	1: 100.80 ± 19.20 2: 127.20 ± 24.00	-26.40 (-45.84, -6.96)	0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation at 1 week Reintubation at 72 h	4: 0/10 5: 0/9 1: 0/10 2: 2/9	1.00 0.18 (0.01, 3.31)	1.00 0.25
	Combined Endpoint: Nonextubation + Reintubation	1: 0/10 2: 2/9	0.18 (0.01, 3.31)	0.25
Esteban (1995) int 1: Pressure Support (± CPAP) int 2: Synchronized (± CPAP) int 3: Multiple Daily T-Piece int 4: Once Daily T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Weaning (h)	1: 96.00 ± 180.00 2: 120.00 ± 144.00 3: 72.00 ± 72.00 4: 72.00 ± 90.00	1 vs. 4: 24.00 (-45.74, 93.74) 2 vs. 4: 48.00 (-12.34, 108.34) 3 vs. 4: 0.00 (-39.81, 39.81) 1 vs. 3: 24.00 (-41.69, 89.69) 2 vs. 3: 48.00 (-7.65, 103.65) 1 vs. 2: -24.00 (-104.31, 56.31)	0.50 0.12 1.00 0.47 0.09 0.56
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation at 14 d Reintubation at 48 h Combined Endpoint: Nonextubation + Reintubation	1: 4/37 2: 5/29 3: 1/33 4: 1/31 1: 7/33 2: 4/24 3: 5/32 4: 4/30 1: 11/37 2: 9/29 3: 6/33 4: 5/31	1 vs. 4: 2.53 (0.42, 15.09) 2 vs. 4: 3.91 (0.69, 22.18) 3 vs. 4: 0.94 (0.10, 8.59) 1 vs. 3: 2.68 (0.45, 16.06) 2 vs. 3: 4.16 (0.73, 23.61) 1 vs. 2: 0.65 (0.20, 2.04) 1 vs. 4: 1.52 (0.53, 4.40) 2 vs. 4: 1.24 (0.38, 4.10) 3 vs. 4: 1.15 (0.37, 3.61) 1 vs. 3: 1.32 (0.49, 3.56) 2 vs. 3: 1.08 (0.35, 3.35) 1 vs. 2: 1.23 (0.43, 3.50) 1 vs. 4: 1.76 (1.71, 4.32) 2 vs. 4: 1.84 (0.73, 4.64) 3 vs. 4: 1.11 (0.40, 3.10) 1 vs. 3: 1.58 (0.68, 3.67) 2 vs. 3: 1.66 (0.70, 3.95) 1 vs. 2: 0.95 (0.70, 1.94)	0.31 0.12 0.96 0.28 0.11 0.46 0.44 0.72 0.81 0.58 0.89 0.70 0.22 0.19 0.84 0.29 0.25 0.89
Nava (1998) int 1: Extubation and Noninvasive Positive Pressure Ventilation int 2: Pressure Support (± CPAP)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 15.10 ± 5.40 2: 24.00 ±13.70 1: 244.80 ± 163.20 2: 398.40 ± 283.20	-8.90 (-14.67, -3.13) -153.60 (-281.73, -25.47)	<0.01 0.02
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	60-day Mortality Nosocomial Pneumonia Nasal Abrasion Patients Requiring Long Term Ventilation	1: 2/25 2: 7/25 1: 0/25 2: 7/25 1: 14/25 2: 0/25 1: 1/25 2: 2/25	0.33 (0.09, 1.25) 0.07 (0.00, 1.11) 29.00 (1.83, 460.63) 0.60 (0.09, 4.22)	0.10 0.06 0.02 0.61
Girault (1999) int 1: Noninvasive Ventilation int 2: Pressure Support	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay Hospital Length of Stay Duration of Intubation	1: 12.35 ± 6.82 2: 14.06 ± 7.54 1: 27.12 ± 14.33 2: 27.69 ± 13.09 1: 4.56 ± 1.85 2: 7.69 ± 3.79	-1.71 (-6.61, -3.19) -0.57 (-9.95, 8.81) -3.13 (-5.15, -1.11)	0.49 0.91 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality 90-Day Mortality Reintubation Arrhythmias Nosocomial Pneumonia	1: 0/17 2: 2/16 1: 0/17 2: 2/16 1: 4/17 2: 4/16 1: 0/17 2: 1/16 1: 1/17 2: 1/16	0.19 (0.01, 3.64) 0.19 (0.01, 3.64) 0.94 (0.31, 2.89) 0.31 (0.01, 7.18) 0.94 (0.11, 8.18)	0.27 0.27 0.92 0.47 0.96
Studies Comparing Alternative Ventilation Modes for Weans Lasting Less Than 48 Hours
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Chopin (1989) int 1: CO₂ Mandatory Ventilation (No CPAP) int 2: Intermittent Mandatory Ventilation (No CPAP) int 3: Multiple Daily T-Piece	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation at 24 h Reintubation Combined Endpoint: Nonextubation + Reintubation	1: 1/14 2: 9/14 1: 4/14 1: 0/13 2: 0/5 3: 0/10 1: 1/14 2: 9/14 3: 4/14	1 vs. 3: 0.33 (0.06, 1.82) 2 vs. 3: 2.11 (0.90, 4.96) 1 vs. 2: 0.16 (0.03, 0.75) 1 vs. 3: 1:00 2 vs. 3: 1:00 1 vs. 2: 1:00 1 vs. 3: 0.33 (0.06, 1.82) 2 vs. 3: 2.11 (0.90, 4.96) 1 vs. 2: 0.16 (0.03, 0.75)	0.20 0.09 0.02 1.00 1.00 1.00 0.20 0.09 0.02
Davis (1989) int 1: IMV (No CPAP) int 2: Mandatory Minute Ventilation (No CPAP)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Successful Weaning	1: 33.30 ± 21.00 2: 4.75 ± 1.50	28.55 (19.77, 37.33)	<0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation	1: 5/18 2: 5/22	1.22 (0.44, 3.34)	0.70
Esen (1992) int 1: Pressure Support (No CPAP) int 2: Intermittent Mandatory Ventilation (No CPAP)	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation/Day Duration of Weaning/Day	1: 19.10 ± 2.30 2: 22.40 ± 3.10 1: 6.30 ± 3.10 2: 9.90 ± 2.70	-3.30 (-4.99, -1.61) -3.60 (-5.40, -1.80)	<0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation at 48 h Reintubation at 48 h Combined Endpoint: Nonextubation + Reintubation	1: 3/20 2: 5/20 1: 0/17 2: 0/15 1: 3/20 2: 5/20	0.64 (0.19, 2.10) 1.00 0.64 (0.19, 2.10)	0.46 1.0 0.46
Studies Comparing Weaning Protocols to Physician-directed Weaning
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Strickland (1993) int 1: Computer-directed Wean int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Weaning (h)	1: 18.70 ± 5.90 2: 25.60 ± 5.60	-6.90 (-12.88, -0.92)	0.02
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation Reintubation Combined Endpoint: Nonextubation + Reintubation	2: 2/9 3: 4/6 1: 0/7 2: 2/2 1: 2/49 2: 6/6	0.38 (0.12, 1.24) 0.07 (0.00, 0.97) 0.26 (0.09, 0.76)	0.11 0.55 0.01
Ely (1996) int 1: Daily Screening ± T-Piece Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	difference in Means (95% CI)
	ICU Length of Stay (d) Hospital Length of Stay (d) Duration of Mechanical Ventilation (h) Duration of Weaning (h)	1: 8.00 ± 10.50 2: 9.00 ± 8.25 1: 14.00 ± 12.75 2: 15.50 ± 18.00 1: 108.00 ± 126.00 2: 144.00 ± 144.00 1: 24.00 ± 36.00 2: 72.00 ± 90.00	-1.00 (-3.14, 1.14) -1.50 (-5.03, 2.03) -36.00 (-66.64, -5.36) -48.00 (-63.55, -32.45)	0.36 0.41 0.02 <0.01
Ely (1996) int 1: Daily Screening ± T-Piece Protocol int 2: Physician-directed Wean	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Mechanical Ventilation for >21 days Self-extubation Reintubation	1: 9/149 2: 20/151 1: 2/149 2: 5/151 1: 5/149 2: 12/151	0.47 (0.23, 0.98) 0.46 (0.11, 2.02) 0.45 (0.17, 1.18)	0.04 0.30 0.11
Kollef (1997) int 1: Protocol by Nurse and Respiratory Therapist int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Hospital Length of Stay (d) Duration of Intubation (h)	1: 12.70 ± 9.40 2: 14.20 ±11.70 1: 35.00 ± 74.25 2: 44.00 ± 141.00	-1.50 (-3.70, 0.70) -9.00 (-32.36, 14.36)	0.18 0.45
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Reintubation Requiring Mechanical Ventilation >7 d Combined Endpoint: Nonextubation + Reintubation	1: 40/179 2: 42/178 1: 23/158 2: 18/147 1: 21/179 2: 31/178 1: 44/179 2: 49/178	0.95 (0.65, 1.38) 1.18 (0.67, 2.08) 0.68 (0.41, 1.13) 0.89 (0.63, 1.27)	0.78 0.56 0.13 0.53
Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (Anesthesia intervention)
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Cheng (1996a) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (d) Duration of Mechanical Ventilation (h) 24-hour CPK 48-hour CPK Duration of Ischemia	1: 29.20 ± 11.70 2: g30.90 ± 12.80 1: g7.00 ± 2.50 2: g8.20 ± 3.50 1: g4.10 ± 1.10 2: g18.90 ± 1.40 1: g14.00 ± xx ¹ 2: g18.00 ± xx 1: g12.00 ± xx 2: g15.00 ± xx 1: g156.60 ± 143.20 2: g107.90 ± 119.50	-1.70 (-6.46, 3.06) -1.20 (-2.38, -0.02) -14.80 (-15.29, -14.31) -4.00 -3.00 48.70 (1.51, 95.89)	0.48 0.05 <0.01 <0.05 <0.05 0.04
Cheng (1996a) int 1: Early Extubation int 2: Late Extubation	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	30-day Mortality Reintubation Nonextubation Myocardial Infarction 24-hour Ischemic Incidence 48-hour Ischemic Incidence Combined Endpoint: Nonextubation + Reintubation	3: 0/60 4: 3/60 1: 1/51 2: 0/51 1: 9/60 2: 9/60 1: 0/60 2: 4/60 1: 10/51 2: 3/51 1: 3/51 2: 2/51 1: 10/60 2: 9/60	0.14 (0.01, 2.71) 3.00 (0.13, 71.94) 1.00 (0.44, 2.28) 0.11 (0.01, 2.02) 3.00 (0.95, 9.44) 1.40 (0.29, 6.77) 1.11 (0.50, 2.46)	0.19 0.50 1.00 0.14 0.06 0.68 0.81
Berry (1998) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (d) Duration of Mechanical Ventilation (h) 24-hour CPK 48-hour CPK Ischemia (Area Under ROC) Maximum ST Depression Ischemic Burden	1: 48.00 ± 0.00 2: 48.00 ± 36.00 1: 8.00 ± 4.50 2: 8.00 ± 2.25 1: 1.83 ± 3.15 2: 12.62 ± 9.30 1: 56.00 ± 188.25 2: 57.00 ± 42.00 1: 42.00 ± 126.75 2: 40.00 ± 110.25 1: 10.00 ± 29.03 2: 8.23 ± 32.10 1: 1.28 ± 0.98 2: 1.30 ± 0.45 1: 5.65 ± 25.35 2: 4.50 ± 19.95	0.00 (-10.76, 10.76) 0.00 (-1.52, 1.52) -10.79 (-13.73, -7.85) -1.00 (-59.31, 57.31) 2.00 (-48.55, 52.55) 1.77 (-11.23, 14.77) -0.02 (-0.34, 0.30) 1.15 (-8.56, 10.86)	1.00 1.00 <0.01 0.97 0.94 0.79 0.90 0.82
Berry (1998) int 1: Early Extubation int 2: Late Extubation	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Hospital Mortality Myocardial Infarction Arrhythmias Ischemia	1: 0/43 2: 2/42 1: 0/43 2: 2/42 1: 2/43 2: 2/42 1: 0/43 2: 0/42 1: 22/43 2: 17/42	0.20 (0.01, 3.95) 0.20 (0.01, 3.95) 0.98 (0.18, 5.36) 1.00 1.26 (0.79, 1.99)	0.29 0.29 0.98 1.00 0.33
Michalopoulos (1998) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 16.08 ± 1.30 2: 23.04 ± 1.20 1: 7.30 ± 0.80 2: 8.40 ± 0.90 1: 7.30 ± 0.70 2: 11.60 ± 1.30	-6.96 (-7.37, -6.55) -1.10 (-1.38, -0.82) -4.30 (-4.64, -3.96)	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Myocardial Infarction Arrhythmias Ischemia Reintubation Hospital Mortality	1: 0/72 2: 0/72 1: 8/72 2: 9/72 1: 3/72 2: 4/72 1: 0/72 2: 0/72 1: 0/72 1: 0/72	1.00 0.89 (0.38, 2.13) 0.78 (0.20, 3.03) 1.00 1.00	1.00 0.80 0.72 1.00 100
Engoren (1998) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 21.00± 6.00 2: 23.00± 9.00 1: 5.10 ± 1.80 2: 6.00 ± 3.00 1: 6.5± 3.4 2: 7.5 ± 4.2	-2.00 (-5.58, 1.58) -0.90 (-2.06, 0.26) -61.00 (-168.00, 46.00)	0.27 0.13 0.26
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Reintubation Myocardial Infarction	1: 0/35 2: 0/35 1: 0/35 2: 0/35 1: 0/35 2: 1/35	1.00 1.00 0.33 (0.01, 7.91)	1.00 1.00 0.50
Silbert (1998) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95%CI)
	Hospital Length of Stay (d) Duration of Mechanical Ventilation (h) Mean Total CPK	1: 8.00 ± 19.50 2: 7.00 ± 11.25 1: 4.00 ± 11.25 2: 7.00 ± 12.68 1: 766.00 ± 428.00 2: 998.00 ± 551.00	1.00 (-5.90, 7.90) -3.00 (-8.27, 2.27) -232.00 (-449.86,-14.14)	0.78 0.26 0.04
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Reintubation Myocardial Infarction	1: 1/38 2: 0/42 1: 0/38 2: 0/42 1: 0/38 2: 0/42	3.31 (0.14, 78.91) 1.00 1.00	0.46 1.00 1.00
Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (ICU Intervention)
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Quasha (1980) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Duration of Mechanical Ventilation (h)	1: 46.08 ± 12.00 2: 57.12 ± 29.04 1: 2.00 ± 2.00 2: 18.00 ± 3.00	-11.04 (-26.24, 4.16) -16.00 (-17.71,-14.29)	0.15 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation Myocardial Infarction Arrhythmias	3: 1/18 4: 0/20 1: 0/18 2: 3/20 1: 4/18 2: 6/20	3.32 (0.14, 76.68) 0.16 (0.01, 2.86) 0.77 (0.28, 2.14)	0.45 0.21 0.61
Shackford (1981) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Duration of Mechanical Ventilation (h)	1: 55.20 ± 9.90 2: 69.60 ± 20.36 1: 3.30 ± 2.06 2: 18.30 ± 2.12	-14.40 (-25.11, -3.69) -15.00 (-16.39, -13.61)	0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Reintubation	1: 0/17 2: 0/18 1: 0/17 2: 0/18	1.00 1.00	1.00 1.00
Tempe (1995) int 1: Early Extubation int 2: Late Extubation	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 0/50 2: 0/50	1.00	1.00
Reyes (1997) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Duration of Mechanical Ventilation (h) Duration of Intubation (h)	1: 27.00 ± xx ¹ 2: 44.00 ± xx 1: 8.52 ± xx 2: 19.00 ± xx 1: 10.00 ± xx 2: 21.00 ± xx	-17.00 -10.48 -11.00	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	30-Day Mortality Reintubation ICU Discharge at 24 h	1: 18/201 2: 15/203 1: 7/201 2: 2/203 1: 89/201 2: 62/203	1.21 (0.63, 2.30) 3.03 (0.73, 12.51) 1.45 (1.12, 1.87)	0.57 0.13 0.01
Dumas (1999) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Ventilation (h)	1: 3.49 ± 2.21 2: 10.32 ± 1.75	-6.83 (-7.96, -5.70)	<0.01
Pediatric Studies of Corticosteroids to Prevent Post-Extubation Airway Complications
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Tellez (1991) int 1: Steroids int 2: No Steroids	Binary Variables	Proportion with Event	Relative Risk (95% CI)
Tellez (1991) int 1: Steroids int 2: No Steroids	Reintubation Stridor	1: 9/76 2: 4/77 1: 16/76 2: 23/77	2.14 (0.73, 6.27) 0.71 (0.41, 1.23)	0.17 0.22
Anene (1996) int 1: Steriods int 2: No Steroids	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Croup Score at 10 min Croup Score at 6 h Croup Score at 12 h Croup Score at 24 h	1: 1.00 ± xx ¹ 2: 2.00 ± xx 1: 0.00 ± xx 2: 1.00 ± xx 1: 0.00 ± xx 2: 0.50 ± xx 1: 0.00 ± xx 2: 0.00 ± xx	-1.00 -1.00 -0.50 0.00	<0.01 <0.01 <0.01 >0.05
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation Stridor at 10 min Stridor at 6 hr Stridor at 12 hr Stridor at 24 hr Racemic Epinephrine	1: 0/31 2: 7/32 1: 14/31 2: 28/32 1: 8/31 2: 22/28 1: 2/31 2: 13/26 1: 1/31 2: 4/25 1: 4/31 2: 22/32	0.07 (0.00, 1.15) 0.52 (0.35, 0.78) 0.34 (0.19, 0.63) 0.16 (0.04, 0.54) 0.27 (0.05, 1.59) 0.21 (0.09, 0.50)	0.06 <0.01 <0.01 <0.01 0.15 <0.01
Harel (1997) int 1: Steriods int 2: No Steroids	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Stridor Score	1: 5.08 ± 2.84 2: 6.18 ± 3.37	-1.10 (-3.64, 1.44)	0.40
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation Tracheostomy	1: 3/12 2: 5/11 1: 3/12 2: 0/11	0.59 (0.20, 1.71) 6.44 (0.37, 111.66)	0.33 0.20
Adult Studies of Corticosteroids to Prevent Post-Extubation Airway Complications
Gaussorgues (1987) int 1: Steroids int 2: No Steroids	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation	1: 312 ± 264 2: 384 ± 216	-0.72 (-128.91,-15.09)	0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation Laryngeal Lesions	1: 4/138 2: 0/138 1: 4/138 2: 2/138	9.00 (0.49, 165.59) 1.80 (0.39, 8.30)	0.14 0.45
Darmon (1992) int 1: Steroids int 2: No Steroids	Binary Variables	Proportion with Event	Relative Risk (95% CI)
Darmon (1992) int 1: Steroids int 2: No Steroids	Reintubation Laryngeal Lesions	1: 2/327 2: 5/337 1: 11/327 2: 17/337	0.47 (0.11, 2.07) 0.68 (0.33, 1.40)	0.32 0.29
Ho (1996) int 1: Steroids int 2: No Steroids	Binary Variables	Proportion with Event	Relative Risk (95% CI)
Ho (1996) int 1: Steroids int 2: No Steroids	Reintubation Stridor	1: 0/39 2: 1/38 1: 7/39 2: 10/38	0.32 (0.01, 7.73) 0.70 (0.31, 1.59)	0.49 0.39
Chaney (1998) int 1: Steroids int 2: No Steroids	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (h)	1: 12.82 ± 4.90 2: 10.07 ± 5.25	2.75 (0.18, 5.32)	0.04
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation	1: 0/30 2: 2/30	0.20 (0.01, 4.00)	0.29
Studies of Enteral Nutrition
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
al-Saady (1989) int 1: High Fat Low Carbohydrate Feed int 2: Isocaloric Feed	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Change ² in Respiratory Rate Change in Tidal Volume Change in PaCO₂ Change in PaO₂ Duration of Mechanical Ventilation From Time That Feed Starts (h)	1: 0.10 ± 0.60 2: 0.20 ± 2.40 1: 40.20 ± 50.50 2: 46.10 ± 75.60 1: 1.00 ± 0.70 2: 0.20 ±0.80 1: 0.60 ± 2.10 2: 0.50 ±3.80 1: 86.10 ± 17.80 2: 148.70 ± 36.70	-0.10 (-1.71, 1.51) -5.90 (-63.73, 51.93) 0.80 (0.13, 1.47) 0.10 (-2.68, 2.88) -62.60 ( -88.87, -36.33)	0.90 0.84 0.02 0.94 <0.01
Vandenberg (1994) int 1: High Fat Low Carbohydrate Feed int 2: Isocaloric Feed	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Respiratory Quotient Minute Ventilation During Weaning	1: 0.72 ± 0.02 2: 0.86 ± 0.02 1: 8.80 ± 0.90 2: 10.50 ± 0.80	-0.14 (-0.16, -0.12) -1.70 (-2.35, -1.05)	<0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Spontaneous Breathing for 3 h on CPAP	1: 12/14 2: 13/16	1.05 ( 0.78, 1.43)	0.74
Miscellaneous Studies
Author (Year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Niehoff (1988) int 1: Pulse Oximetry and Capnography int 2: Periodic ABG	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	No. Of ABGs Performed Duration of Mechanical Ventilation (h)	1: 5.90 ± 2.70 2: 10.50 ± 1.80 2: 18.80 ± 2.04 1: 19.70 ± 1.90	-4.60 (-6.49, -2.71) -0.90 (-2.52, 0.72)	<0.01 0.27
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation Reintubation Combined Endpoints: Nonextubation + Reintubation	1: 0/12 2: 1/12 1: 0/12 2: 0/11 1: 0/12 2: 1/12	0.33 (0.01, 7.42) 1.00 0.33 (0.01, 7.42)	0.49 1.00 0.49
Holliday (1990) int 1: Relaxation Biofeedback int 2: No Relaxation Biofeedback	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Change in MIP Change in Tidal Volume Change in Minute Ventilation (L/min) Duration of Mechanical Ventilation (d)	1: 12 ± xx ¹ 2: 6 ± xx 1: 120 ± xx 2: 51 ± xx 1: 4.41 ± xx 2: 2.67 ± xx 1: 20.6 ± 8.9 2: 32.6 ± 17.6	-12.0 (-20.6, -3.4)	0.01
Holliday (1990) int 1: Relaxation Biofeedback int 2: No Relaxation Biofeedback	Binary Variables	Proportion with Event	Relative Risk (98% CI)	P Value
	Nonextubation	2/20 3/16	0.58 (0.13, 2.57)	0.47
Gust (1996) int 1: Nasal BiPAP (30 min) int 2: CPAP (30 min) int 3: Routine Chest Physiotherapy (10 min) + O₂ by nasal cannula	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Change in Pulmonary Blood Volume Index From End of T-piece Trial to 90 min	1: 17 ± xx ¹ 2: 9 ± xx 3: 17 ± xx	1 vs. 3: 0 2 vs. 3: -8 1 vs. 2: 8
	Extravascular Lung Water From End of T-piece Trial to 90 min	1: 0.1 ± xx 2: 0.4 ± xx 3: -0.6 ± xx	1 vs. 3: 0.7 2 vs. 3: 1.0 1 vs. 2: -0.3
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 0/25 2: 0/25 3: 0/25	1 vs 3: 1.00 2 vs 3: 1.00 1 vs 2: 1.00	1.00 1.00 1.00
Pichard (1996) int 1: Recombinant Growth Hormone int 2: No Recombinant Growth Hormone	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Cumulative Duration of Mechanical Support (h) During Weaning	1: 235.60 ± 55.66 2: 245.40 ± 46.49	-9.80 (-54.75, 35.15)	0.67
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation at Day 12	1: 7/10 2: 7/10	1.00 (0.58, 1.72)	1.00
Lee (1998)	Binary Variables	Proportion with Event	Relative Risk (95% CI)
Jiang (1999) int 1: Nasal BiPAP 30 Minutes int 2: Oxygen by Nasal Prongs and Chest Physiotherapy	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 13/47 2: 7/46	1.76 (0.80, 3.91)	0.16
int 1: Accupuncture int 2: Control	Laryngospasm	1: 2/38 2: 9/38	0.26 (0.07, 0.98)	0.05

Evidence Table 8. Pooled results of randomized trials

Studies Comparing Alternative Ventilation Modes for Trials of Unassisted Breathing
CPAP vs. T-Piece
Outcome	Author (Year)	Relative Risk (95% CI)	Summary RR (95% CI)	Heterogeneity X²(P Value)
Nonextubation Rate	Feeley (1975)	1.94 (0.50, 7.47)	1.66 (0.60, 4.64)	0.12 (P=0.79)
Nonextubation Rate	Jones (1991)	1.35 (0.28, 6.54)	1.66 (0.60, 4.64)	0.12 (P=0.79)
Reintubation Rate	Feeley (1975)	4.00 (0.18, 87.19)	1.71 (0.42, 6.97)	0.37 (P=0.54)
Reintubation Rate	Jones (1991)	1.37 (0.28, 6.64)	1.71 (0.42, 6.97)	0.37 (P=0.54)
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support-Noninvasive Ventilation vs. Pressure Support
(1) Binary Variables
Outcome	Author (Year)	Difference (95% CI)	Summary Difference (95% CI)	Heterogeneity X² (P Value)
Mortality	Nava (1998)	0.33 (0.09, 1.25)	0.30 (0.09, 1.02)	0.19 (P=0.73)
Mortality	Girault (1999)	0.19 (0.01, 3.66)	0.30 (0.09, 1.02)	0.19 (P=0.73)
Nosocomial Pneumonia	Nava (1998)	0.07 (0.00, 1.11)	0.29 (0.02, 3.88)	2.15 (P=0.14)
Nosocomial Pneumonia	Girault (1999)	0.94 (0.11, 8.22)	0.29 (0.02, 3.88)	2.15 (P=0.14)
(2) Continuous Variables
ICU Length of Stay	Nava (1998)	-8.90 (-14.67, 3.13)	-5.14 (-12.17, 1.90)	3.46 (P=0.06)
ICU Length of Stay	Girault (1999)	-1.71 (-6.61, 3.19)	-5.14 (-12.17, 1.90)	3.46 (P=0.06)
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support-Duration of Weaning
(1) Pressure Support vs. Multiple Daily T-Piece
Outcome	Author (Year)	Difference (95% CI)	Summary Difference (95% CI)	Heterogeneity X² (P Value)
Duration of Weaning	Brochard (1994)	-67.20 (-143.29, 8.89)	-19.50 (-108.78, 69.79)	3.16 (P=0.08)
Duration of Weaning	Esteban (1995)	24.00 (-41.69, 86.69)	-19.50 (-108.78, 69.79)	3.16 (P=0.08)
(2) SIMV vs. Multiple Daily T-Piece
Duration of Weaning	Brochard (1994)	33.60 (-54.69, 121.89)	43.91 (-3.17, 90.98)	0.07 (P=0.79)
Duration of Weaning	Esteban (1995)	48.00 (-7.65, 103.65)	43.91 (-3.17, 90.98)	0.07 (P=0.79)
(3) PS vs. SIMV
Duration of Weaning	Brochard (1994)	-100.80 (-175.09, -26.51)	-63.98 (-139.18, 11.22)	1.89 (P=0.17)
Duration of Weaning	Esteban (1995)	-24.00 (-104.31, 56.31)	-63.98 (-139.18, 11.22)	1.89 (P=0.17)
Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support-Extubation Outcomes
a) Pressure Support vs. Multiple Daily T-Piece
Outcome	Author (Year)	Relative Risk (95% CI)	Summary RR (95% CI)	Heterogeneity X² (P Value)
Combined: Nonextubation and Reintubation	Brochard (1994)	0.54 (0.26, 1.13)	0.91 (0.32, 2.58)	3.52 (P=0.06)
Combined: Nonextubation and Reintubation	Esteban (1995)	1.58 (0.68, 3.68)	0.91 (0.32, 2.58)	3.52 (P=0.06)
b) SIMV vs. Multiple Daily T-Piece
Combined: Nonextubation and Reintubation	Brochard (1994)	0.98 (0.59, 1.63)	1.13 (0.71, 1.78)	1.06 (P=0.30)
Combined: Nonextubation and Reintubation	Esteban (1995)	1.66 (0.69, 3.95)	1.13 (0.71, 1.78)	1.06 (P=0.30)
c) PS vs. SIMV
Combined: Nonextubation and Reintubation	Brochard (1994)	0.56 (0.27, 1.14)	0.73 (0.43, 1.24)	1.09 (P=0.30)
Combined: Nonextubation and Reintubation	Esteban (1995)	0.96 (0.47, 1.95)	0.73 (0.43, 1.24)	1.09 (P=0.30)
Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (Anesthesia Intervention)
(1) Binary Variables
Outcome	Author (Year)	Relative Risk (95% CI)	Summary RR (95% CI)	Heterogeneity X² (P Value)
Mortality	Michalopoulos (1998)	1.00 (0.02, 49.73)	0.53 (0.12, 2.35)	2.67 (P=0.61)
	Silbert (1998)	3.31 (0.14, 78.84)
	Berry (1998)	0.20 (0.01, 3.95)
	Cheng (1996a)	0.14 (0.01, 2.71)
	Engoren (1998)	1.00 (0.02, 49.04)
Myocardial Infarction	Cheng (1996a)	0.11 (0.01, 2.02)	0.59 (0.18, 1.94)	1.90 (P=0.75)
	Silbert (1998)	1.10 (0.02, 54.25)
	Berry (1998)	0.98 (0.18, 5.36)
	Michalopoulos (1998)	1.00 (0.02, 49.73)
	Engoren (1998)	0.33 (0.01, 7.91)
Arrhythmias	Berry (1998)	0.98 (0.02, 48.15)	0.90 (0.39, 2.09)	0.01 (P = 0.97)
Arrhythmias	Michalopoulos (1998)	0.89 (0.38, 2.13)	0.90 (0.39, 2.09)	0.01 (P = 0.97)
Reintubation	Cheng (1996a)	3.00 (0.13, 72.21)	1.48 (0.24, 9.26)	0.29 (P=0.96)
	Michalopoulos (1998)	1.00 (0.02, 49.73)
	Silbert (1998)	0.91 (0.02, 44.63)
	Engoren (1998)	1.00 (0.02, 49.04)
Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (Anesthesia Intervention)
(2) Continuous Variables
Outcome	Author (Year)	Difference (95% CI)	Summary Difference (95% CI)	Heterogeneity X² (P Value)
ICU Length of Stay	Cheng (1996a)	-1.70 (-6.46, 3.06)	-3.59 (-7.49, 0.30)	13.37 (P<0.01)
	Berry (1998)	0.00 (-10.76, 10.76)
	Michalopoulos (1998)	-6.96 (-7.37, -6.55)
	Engoren (1998)	-2.00 (-5.58, 1.58)
Hospital Length of Stay	Cheng (1996a)	-1.20 (-2.38, -0.02)	-1.06 (-1.32, -0.80)	2.42 (P=0.66)
	Silbert (1998)	1.00 (-5.90, 7.90)
	Berry (1998)	0.00 (-1.52, 1.52)
	Michalopoulos (1998)	-1.10 (-1.38, -0.82)
	Engoren (1998)	-0.90 (-2.06, 0.26)
Duration of Mechanical Ventilation	Cheng (1996a)	-14.80 (-15.29, -14.31)	-6.86 (-13.26, -0.47)	1253.49 (P<0.01)
	Silbert (1998)	-3.00 (-8.27, 2.27)
	Berry (1998)	-10.79 (-13.73, -7.85)
	Michalopoulos (1998)	-4.30 (-4.64, -3.96)
	Engoren (1998)	-1.02 (-2.08, 0.77)
Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (ICU Interventions)
(1) Binary Variables
Outcome	Author (Year)	Relative Risk (95% CI)	Summary RR (95% CI)	Heterogeneity X² (P Value)
ICU Mortality	Shackford (1981)	1.06 (0.02, 50.44)	1.20 (0.63, 2.27)	0.00 (P=1.00)
ICU Mortality	Reyes (1997)	1.21 (0.63, 2.30)	1.20 (0.63, 2.27)	0.00 (P=1.00)
Reintubation	Quasha (1980)	3.32 (0.14, 76.60)	2.69 (1.06, 6.87)	0.54 (P=0.91)
	Shackford (1981)	1.06 (0.02, 50.44)
	Tempe (1995)	1.00 (0.02, 49.44)
Arrhythmias	Quasha (1980)	0.77 (0.27, 2.14)	0.60 (0.36, 1.02)	0.38 (P=0.83)
	Shackford (1981)	1.06 (0.02, 50.44)
	Reyes (1997)	0.55 (0.29, 1.02)
(2) Continuous Variables
ICU Length of Stay	Quasha (1980)	-0.46 (-1.03, 0.11)	-0.55 (-0.90, -0.19)	0.14 (P=0.71)
ICU Length of Stay	Shackford (1981)	-0.60 (-1.05, -0.15)	-0.55 (-0.90, -0.19)	0.14 (P=0.71)
Duration of Mechanical Ventilation	Quasha (1980)	-16.00 (-17.58, -14.42)	-12.59 (-18.71, -6.47)	115.99 (P<0.01)
	Shackford (1981)	-15.00 (-16.39, -13.61)
	Dumas (1999)	-6.83 (-7.96, -5.70)
Pediatric Studies of Corticosteroids to Prevent Postextubation Airway Complications
Outcome	Author Year)	Relative Risk (95% CI)	Summary RR (95% CI)	Heterogeneity X² (P Value)
Reintubation	Tellez (1991)	2.14 (0.73, 6.28)	0.68 (0.16, 2.97)	6.26 (P=0.04)
	Anene (1996)	0.07 (0.00, 1.15)
	Harel (1997)	0.59 (0.20, 1.74)
Stridor	Tellez (1991)	0.71 (0.41, 1.23)	0.58 (0.42, 0.81)	0.77 (P=0.38)
Stridor	Anene (1996)	0.52 (0.35, 0.79)	0.58 (0.42, 0.81)	0.77 (P=0.38)
Adult Studies of Corticosteroids to Prevent Postextubation Airway Complications
Reintubation	Gaussorgues (1987)	9.00 (0.49, 165.60)	0.93 (0.15, 5.81)	3.45 (P=0.18)
	Darmon (1992)	0.47 (0.11, 2.07)
	Ho (1996)	0.33 (0.01, 7.74)
Lanyngeal Lesions	Gaussorgues (1987)	1.80 (0.39, 8.30)	0.87 (0.38, 2.00)	1.28 (P=0.26)
Lanyngeal Lesions	Darmon (1992)	0.68 (0.33, 1.40)	0.87 (0.38, 2.00)	1.28 (P=0.26)

Evidence Table 9. Methodologic characteristics of nonrandomized controlled clinical trials, grouped according to intervention type

Nonrandomized Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support
Author (year)	ICU Population	Diagnoses	Baseline Similarity	Cointervention Similarity	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Patel (1999)	Adult ICU patients (n=42)	COPD, pneumonia, neurological, airway protection	Yes for: age, prestudy time on ventilation, P/F ratio, proportion with pneumonia, COPD, NMD	Not demonstrated	Yes	No	No
Hilbert (1998a)	Adult MICU (n=60)	Postextubation hypercapnia respiratory failure, COPD	Yes for: age, prestudy time on ventilation, proportion with VAP, SAPS, P/F ratio	Yes for proportion ever received, systemic steroids, diuretics, antibiotics	N/A	N/A	No
Nonrandomized Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support Lasting Less Than 48 Hours
Tomlinson (1989)	Patients in a tertiary care medical-surgical ICU (n=165)	COPD, CHF, post-op, neurological, cardiac bypass surgery, cardiac valve surgery, trauma	Yes for: age, proportion post-op	Not demonstrated	Yes	No	No
Rathgeber (1997)	Adult postcardiac surgery (n=596)	Cardiac bypass surgery	Yes for: age, proportion post-op, prestudy time on ventilation, proportion with pneumonia, VAP, COPD, NMD, ARDS	No: more sedatives in T-piece group	Yes	Yes	No
Nonrandomized Studies Comparing Weaning Protocols to Physician-directed Weaning
Author (year)	ICU Population	Diagnoses	Baseline Similarity	Cointervention Similarity	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Foster (1984)	Adult postcardiac surgery (n=63)	Cardiac bypass surgery	Yes for: age, proportion post-op	Not demonstrated	Yes	Yes	No
Tong (1991)	(n=54)	Postoperative	Yes for: age, proportion post-op	Not demonstrated	No	No	No
Rotello (1992)	Adult general (n=63)	COPD, pneumonia, post-op, trauma	Yes for: proportion with pneumonia, COPD	Not demonstrated	Yes	No	No
Wood (1995)	Adult postcardiac surgery (n=284)	Cardiac bypass surgery, cardiac valve surgery	Yes for: age, proportion post-op	Not demonstrated	Yes	Yes	No
Saura (1996a)	Adult general (n=101)	COPD, neurological	Yes for: age, pre-study time on ventilation, COPD, APACHE II	Not demonstrated	Yes	Yes	No
Results-Nonrandomized Studies Comparing Weaning Protocols with Physician-directed Weaning
Author (year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Djunaedi (1997)	Adult MICU (n=107)	Post-op, trauma	Yes for: age, proportion post-op, APACHE II	Not demonstrated	Yes	Yes	No
Burns (1998)	Adult MICU (n=409)	COPD, asthma, pneumonia, lung injury, post-op, neuromuscular, neurological, airway protection, trauma	Yes for: proportion post-op, prestudy time on ventilation, proportion with NMD	Not demonstrated	Yes	No	No
Horst (1998)	Adult general (n=893)	Postoperative	Yes for: proportion post-op, APACHE II	Not demonstrated	Yes	Yes	No
Kollef (1998a)	Adult and some not reported (n=347)	Surgical	Not demonstrated	Not demonstrated	No	No	No
Kollef (1998b)	Adult general (n=88)	Not reported	Yes for: age, MPM	Not demonstrated	No	No	No
Kollef (1998c)	Adult general (n is not reported)	Not reported	Yes for: age	Not demonstrated	No	No	No
Nonrandomized Studies Comparing Early vs Late Extubation Following Cardiac Surgery (Anesthesia Intervention)
London (1997)	CVICU VA hospitals (n=559)	Cardiac surgery	Yes for: age, proportion post-op, proportion with COPD	Not demonstrated	No	No	No
Nonrandomized Studies Comparing Early vs Late Extubation Following Cardiac Surgery (ICU)
Chong (1993)	Adult cardiac surgery (n=278)	Cardiac bypass surgery, cardiac valve surgery, congenital heart disease	Yes for: age, proportion post-op	Not demonstrated	Yes	Yes	No
Engelman (1994)	Adult postcardiac surgery (n=562)	Cardiac bypass surgery	Yes for: age, proportion post-op	Not demonstrated	No	No	No
Lee (1996)	Adult cardiac surgery (n=690)	Cardiac bypass surgery	Yes for: age, proportion post-op	Not demonstrated	No	Yes	No
Johnson (1997)	Adult cardiac surgery (n=143)	Cardiac bypass surgery	Yes for: age, proportion post-op (matched controls)	Yes for: proportion ever received sedatives, bronchodilators	No	No	No
Quigley (1997)	Adult cardiac surgery (n=532)	Cardiac bypass surgery	Yes for: age, proportion post-op	Not demonstrated	No	No	No
Sugahara (1999)	Adult CVICU (n=34)	Post-op, cardiac bypass surgery, cardiac valve surgery	Yes for: age, proportion post-op, prestudy time on ventilation, receiving sedatives, receiving NM blockers	Yes for: proportion ever received sedatives No for: proportion ever received inotropes	No	No	No
Nonrandomized Studies Comparing Early vs Late Extubation Following Cardiac Surgery (Pediatrics)
Laussen (1996)	Pediatric cardiac surgery (n=102)	ASD repair	Yes for: age, proportion post-op	Not demonstrated	No	No	No
Nonrandomized Studies of Corticosteroids to Prevent Post-Extubation Airway (Pediatrics)
Author (year)	ICU Population	Diagnoses	Baseline Similarity	Cointervention Similarity	Weaning Criteria Reported	Extubation Criteria Reported	Reintubation Criteria Reported
Freezer (1990)	Pediatric ICU (n=59)	Croup failed first extubation	Yes for: age, prestudy time on ventilation No for: history of croup	No for: proportion ever received systemic steroids	No	No	No
Nonrandomized Studies of Enteral Nutrition
Bassili (1981)	Adult medical and surgical ICU patients (n=47)	COPD, Pneumonia, post-op, trauma	Yes for: proportion post-op, pre-study time on ventilation, proportion with COPD	Yes for: proportion ever received enteric feeding	No	No	No

Evidence Table 10. Results of individual nonrandomized controlled clinical trials

Results-Nonrandomized Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support
Author (year) Study Interventions	Outcome	Results	Magnitude of Effect	P Value
Patel (1999) int 1: 24 h 5 PS + 5 PEEP 24 h Intermittent Nasal CPAP int 2: 24 h 5 PS + 5 PEEP 24 h Invasive CPAP	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation within 48 h of extubation	1: 2/20 2: 4/20	0.61 (0.15, 2.56)	0.50
Hilbert (1998a) int 1: Intermittent noninvasive ventilation int 2: Conventional management	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital mortality Reintubation	1: 2/30 2: 6/30 1: 6/30 2: 20/30	0.38 (0.10, 1.51) 0.15 (0.15, 0.66)	0.17 <0.01
Results-Nonrandomized Studies Comparing Alternative Ventilation Modes for Stepwise Reductions in Mechanical Support Lasting Less than 48 Hours
Tomlinson (1989) int 1: IMV (± PEEP) int 2: Multiple Daily T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (h) Duration of Weaning (h)	1: 115.50 ± 479.14 2: 67.40 ± 99.99 1: 5.30 ± 11.88 2: 5.90 ± 14.14	48.10 (-46.96, 143.16) -0.60 (-4.23, 3.03)	0.32 0.75
h = hours; d = days
Rathgeber (1997) int 1: Invasive BiPAP int 2: SIMV with Pressure Support + CPAP int 3: Intermittent T-Piece	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Intubation (h)	1: 10.10 ± 3.30 2: 14.70 ± 4.00 3: 13.20 ± 4.20	1 vs. 3:-3.10 (-4.50,-1.70) 2 vs. 3: 1.50 (0.69, 2.31) 1 vs. 2: -4.60 (-5.85,-3.35)	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 0/658 2: 0/709 3: 1/721	1 vs. 3: 0.37 (0.01, 8.95) 2 vs. 3: 0.34 (0.01, 8.31) 1 vs. 2: 1.08 (0.02,54.23)	0.54 0.51 0.97
Nonrandomized Studies Comparing Weaning Protocols with Physician-directed Weaning
Foster (1984) int 1: Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (h) Duration of Intubation (h) Number of ABGs performed	1: 10.80 ± 4.50 2: 18.20 ± 8.50 1: 9.80 ± 4.40 2: 16.50 ± 8.00 1: 6.60 ± 2.00 2: 11.40 ± 5.30	-7.40 (-10.65, -4.15) -6.70 (-9.79, -3.61) -4.80 (-6.68, -2.92)	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation	1: 22/36 2: 26/27	0.64 (0.49, 0.83)	<0.01
Tong (1991) int 1: Computer-directed int 2: Physician-directed	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	No of ABGs Performed	1: 3.40 ± 0.50 2: 6.20 ± 1.90	-2.80 (-3.85, -1.75)	<0.01
Rotello (1992) int 1: Nurse-directed Oxygen Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Weaning (m) Number of ABGs Performed	1: 170.00 ± 93.00 2: 307.00 ± 131.00 3: 1.06 ± 0.24 4: 2.85 ± 0.69	-137.00 (-199.00,-75.00) -1.79 (-2.02, -1.56)	<0.01 <0.01
Wood (1995) int 1: Respiratory Therapist-directed IMV Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (h) Duration of Weaning (h)	1: 19.78 ± 7.58 2: 21.00 ± 9.60 1: 3.01 ± 2.93 2: 3.30 ± 4.65	-1.22 (-3.62, 1.18) -0.29 (-1.42, 0.84)	0.32 0.61
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Reintubation	1: 1/55 2: 3/142	1.10 (0.17, 7.27)	0.92
Saura (1996) int 1: Protocol-directed Wean int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Mechanical Ventilation (d) Duration of Weaning (d)	1: 16.70 ± 16.50 2: 20.30 ± 13.20 1: 10.40 ± 11.60 2: 14.40 ± 10.30 1: 3.50 ± 3.90 2: 3.60 ± 2.20	-3.60 (-9.43, 2.23) -4.00 (-8.28, 0.28) -0.10 (-1.34, 1.14)	0.23 0.07 0.87
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Nonextubation Reintubation Tracheostomy	1: 4/51 2: 8/50 1: 5/51 2: 4/50 1: 9/51 2: 7/50 1: 1/51 2: 4/50	0.52 (0.18, 1.52) 1.20 (0.37, 3.92) 1.24 (0.52, 2.98) 0.33 (0.05, 1.99)	0.23 0.76 0.63 0.23
Djunaedi (1997) int 1: Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (d)	1: 3.89 ± 4.43 2: 3.18 ± 3.98	0.71 (-0.89, 2.31)	0.39
Burns (1998) int 1: Multidisciplinary Protocol-directed Wean int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Hospital Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 12.70 ± 15.14 2: 14.80 ± 15.68 1: 11.60 ± 12.47 2: 12.90 ± 13.57	-2.10 (-6.73, 2.53) -1.30 (-5.23, 2.63)	0.37 0.52
Horst (1998) int 1: Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (h)	1: 112.60 ± 164.00 2: 170.60 ± 164.00	-58.00 (-79.77, -36.23)	<0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Reintubation	1: 63/515 2: 55/378 1: 2/515 2: 6/378	0.84 (0.60, 1.17) 0.28 (0.07, 1.21)	0.31 0.09
Kollef (1998) int 1: Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 4.40 ± xx ¹ 2: 6.07 ± xx 1: 121.90 ± xx 2: 170.60 ± xx	-1.67 -48.70
Kollef (1998) int 1: Nurse + Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Hospital Length of Stay (d) ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 8.00 ± xx ¹ 2: 11.00 ± xx 1: 4.00 ± xx 2: 8.00 ± xx 1: 72.00 ± xx 2: 144.00 ± xx	-3.00 -4.00 -72.00
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality	1: 14/53 2: 11/35	0.84 (0.44, 1.60)	0.59
Kollef (1998) int 1: Nurse + Respiratory Therapist-directed Weaning Protocol int 2: Physician-directed Wean	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Hospital Length of Stay (d) ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 15.60 ± xx ¹ 2: 20.20 ± xx 1: 5.80 ± xx 2: 8.10 ± xx 1: 21.60 ± xx 2: 112.80 ± xx	-4.60 -2.30 -43.20
Results-Nonrandomized Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (Anesthesia Intervention)
London (1997) int 1: Early int 2: Late	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (h) Duration of Mechanical Ventilation (h)	1: 91.0 ± 145.0 2: 144.0 ± 204.0 1: 228.0 ± 252.0 2: 291.0 ± 213.0 1: 17.3 ± 28.6 2: 27.8 ± 28.3	-53.0 (-82.03, -23.97) -63.0 (-102.12, -23.88) -10.5 (-15.24, -5.76)	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	30-day Mortality Reintubation Arrhythmias Nosocomial Pneumonia	1: 14/304 2: 10/255 1: 15/304 2: 16/255 1: 78/304 2: 56/255 1: 22/304 2: 37/255	1.16 (0.53, 2.52) 0.79 (0.40, 1.55) 1.17 (0.86, 1.57) 0.50 (0.31, 0.83)	0.71 0.49 0.31 0.01
Results-Nonrandomized Studies Comparing Early vs. Late Extubation Following Cardiac Surgery (ICU Intervention)
Chong (1993) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95%CI)
	Hospital Length of Stay (d) Duration of Mechanical Ventilation (h) Duration of Intubation (h)	1: 7.60 ± 3.30 2: 7.90 ± 2.10 1: 1.00 ± xx ¹ 2: 5.00 ± xx 1: 2.00 ± xx 2: 7.00 ± xx	-0.30 (-1.08, 0.48) -4.00 -5.00	0.45 <0.05 <0.05
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Reintubation	1: 2/193 2: 0/80 1: 5/193 2: 0/80	2.08 (0.10, 42.85) 4.58 (0.26, 81.80)	0.64 0.30
Engelman (1994) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Intubation (h)	1: 1.90 ± 0.10 2: 2.40 ± 0.10 1: 15.40 ± 2.00 2: 22.10 ± 1.10	-0.50 (-0.52, -0.48) -6.70 (-6.97, -6.43)	<0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Myocardial Infarction	1: 10/280 2: 11/282 1: 6/280 2: 5/282	0.92 (0.40, 2.09) 1.19 (0.39, 3.66)	0.84 0.76
Lee (1996) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95%CI)
	ICU Length of Stay (d) Hospital Length of Stay (d)	1: 2.03 ± 2.67 2: 2.36 ± 2.93 1: 9.87 ± 8.58 2: 11.84 ± 10.12	-0.33 (-0.75, 0.09) -1.97 (-3.37, -0.57)	0.12 0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Hospital Mortality Myocardial Infarction Arrhythmias Nosocomial Pneumonia	1: 11/362 2: 12/328 1: 13/362 2: 6/328 1: 82/362 2: 63/328 1: 4/362 2: 1/328	0.83 (0.38, 1.83) 1.88 (0.75, 4.74) 1.18 (0.88, 1.58) 2.72 (0.43, 17.15)	0.65 0.18 0.27 0.29
Johnson (1997) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 1.30 ± 4.00 2: 2.80 ± 3.00 1: 7.00 ± 3.50 2: 22.00 ± 9.20	-1.50 (-2.79, -0.21) -15.00 (-18.31, -11.39)	0.02 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nosocomial Pneumonia	1: 2/31 2: 6/112	1.37 (0.34, 5.59)	0.66
Quigley (1997) int 1: Early Extubation int 2: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (d) Hospital Length of Stay (d) Duration of Intubation (h)	1: 1.70 ± 0.80 2: 2.60 ± 0.60 1: 6.40 ± 1.20 2: 7.50 ± 0.90 1: 10.16 ± 10.80 2: 38.40 ± 6.38	-0.90 (-1.02, -0.78) -1.10 (-1.28, -0.92) -28.24 (-29.75, -26.73)	<0.01 <0.01 <0.01
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	ICU Mortality Nonextubation at 24 h ICU Discharge at 24-48 h	1: 5/266 2: 6/266 1: 13/266 2: 266/266 1: 218/266 2: 128/266	0.85 (0.28, 2.60) 0.05 (0.03, 0.09) 1.70 (1.48, 1.95)	0.77 <0.01 <0.01
Sugahara (1999) int 1: Early int 2: Late	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
Sugahara (1999) int 1: Early int 2: Late	ICU Length of Stay (d) Duration of Mechanical Ventilation (h)	1: 4.90 ± 1.80 2: 5.70 ± 2.10 1: 4.10 ± 2.70 2: 5.30 ± 4.40	-0.80 (-2.11, 0.51) -1.20 (-3.65, 1.25)	0.23 0.34
Results-Nonrandomized Studies of Early vs. Late Extubation Following Cardiac Surgery (Pediatrics)
Laussen (1996) int 1: Very Early Extubation (in OR) int 2: Early Extubation int 3: Late Extubation	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	ICU Length of Stay (h) Hospital Length of Stay (d) Duration of Intubation (h)	1: 28.30 ± 11.20 2: 27.40 ± 9.60 3: 31.90 ± 18.70 1: 3.40 ± 0.60 2: 3.50 ± 0.70 3: 5.10 ± 0.60 1: N/A 2: 6.80 ± 8.50 3: 8.30 ± 6.00	1 vs. 3: -3.60 (-11.80, 4.60) 2 vs. 3: -4.50 (-11.02, 2.02) 1 vs. 2: 0.90 (-4.19, 5.99) 1 vs. 3: -1.70 (-2.01, -1.39) 2 vs. 3: -1.60 (-1.89, 1.31) 1 vs. 2: -0.10 (-0.43, 0.23) 2 vs. 3: -1.50 (-4.83, 1.83)	0.39 0.18 0.73 <0.01 <0.01 0.55 0.38
Results-Nonrandomized Studies of Corticosteroids to Prevent Postextubation Airway Complications (Pediatrics)
Freezer (1990) int 1: Steroids int 2: No Steroids	Binary Variables	Proportion with	Relative Risk (95% CI)
Freezer (1990) int 1: Steroids int 2: No Steroids	Failed Reextubation	1: 0/16 2: 26/43	0.05 (0.00, 0.77)	0.03
Results-Nonrandomized Studies of Enteral Nutrition
2705 Bassili (1981) int 1: D5W int 2: TPN or NG Feeds	Continuous Variables	Mean ± Standard Deviation	Difference in Means (95% CI)
	Duration of Mechanical Ventilation (d)	1: 9.2 ± xx ¹ 2: 9.3 ± xx	-0.1
	Binary Variables	Proportion with Event	Relative Risk (95% CI)
	Nonextubation	1: 15/33 2: 1/14	4.47 (0.94, 21.26)	0.06

Evidence Table 11. Characteristics of observational studies

Critical Appraisal Question	Number of Studies
Was there a representative sample of patients?
Yes	31
Unclear	8
No - patients selected according to results of extubation trial (pass or fail)	1
No - artificial case mix (e.g., normal post-op plus pulmonary fibrosis)	29

Is the person deciding on patient status on the dependent variable the same person who is measuring the prediction variables?
Yes	10
Unclear	15
Not reported	12
No - the person deciding on extubation/reintubation/altering level of support is aware of all prediction variables	6
No- the person deciding on extubation/reintubation/altering level of support is aware of some prediction variables	10
No - the person deciding on extubation/reintubation/altering level of support is unaware of predicition variables	9
No - the person deciding on extubation/reintubation/altering level of support is privy to raw data but not derived data	1
No - the person deciding on extubation/reintubation/altering level of support is unable to access predictors	0
No- unclear	2
No - not reported	5

Did the authors report practice patterns with respect to each of the following issues within the study ICU?
Tracheostomy (who, what proportion) - Yes	6
Tracheostomy (who, what proportion) - No	63
NPPV (who, what proportion) - Yes	1
NPPV (who, what proportion) - No	68
Dependent Variable or Outcome (may be more than one choice)	No. of Studies

1. Successful stepwise decrease in level of mechanical support	5
Pressure support (PS)	3
Intermittent mandatory ventilation (IMV)	2
Volume support	0
Daily time on T-piece	0
PEEP	0
Other	2

2. Successful discontinuation assessment test prior to extubation	18
T-piece	9
CPAP	4
CPAP/PS	0
Other	3

3. Successful trial of extubation (when deemed "ready")	30
Duration of monitoring during which reintubation is identified not reported	6
Duration of monitoring during which reintubation is identified <6 hours	0
Duration of monitoring during which reintubation is identified 6.1 to 12 hours	0
Duration of monitoring during which reintubation is identified 12.1 to 24 hours	9
Duration of monitoring during which reintubation is identified 24.1 to 48 hours	7
Duration of monitoring during which reintubation is identified >48 hours	3
Duration of monitoring during which reintubation is identified as other	4
Criteria for failure reported - quantitative criteria	9
Criteria for failure reported - nonquantitative criteria	7
Criteria for failure not reported	5

4. Combination of 2 and 3	13

5. Combination of 1, 2, and 3	2

6. Weaned and successfully extubated any time (outcome evaluated from before the start of the weaning trial until the end of followup)	6

7. Duration of ventilation in COPD patients	1

8. Duration of ventilation in cardiac patients	10
Classification of Predictors	No. of Studies
subjective (e.g., Diaphoresis, anxiety)	10
vital signs (e.g., HR, RR, BP)	64
lung mechanics (e.g., VT, PIP, f/VT)	313
composite scores or derivations (e.g., CROP)	66
level of nonrespiratory care (e.g., inotropes, sedatives)	35
diagnostic category	150
other	302
Classification of Predictor Data
Actual data type
binary	214
categorical	26
continuous (includes plots)	701
Reported Data Type
binary	268
categorical	49
continuous (includes plots)	624
Format of Results (May Be More than One Choice)
allows only 2X2 table	532
allows 2Xn table	40
logistic regression	70
means	354

Evidence Table 12. Methodologic characteristics of observational studies, grouped according to outcome

Successful Stepwise Decrease in Mechanical Support
Author (year)	ICU Population	Diagnoses	Representative Sample	Blinding of Outcome Assessor
Oh (1991)	Adult general (n=20)	COPD, CHF, post-op, cardiac bypass surgery, cardiac valve surgery	Yes	Partial
Linton (1994)	Adult general (n=27)	COPD, pneumonia, CHF, lung injury, post-op	Unclear	Likely unblinded
Stroetz (1995)	Adult general (n=31)	COPD, lung injury	Yes	Likely unblinded
Rivera (1997)	Adult general (n=40)	post-op	No: according to case mix	Unblinded
Successful Discontinuation Assessment
Delooz (1976)	Adult postcardiac surgery (n=41)	Cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded
Hilberman (1976)	Adult (n=124)	Post-op, cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded
Kennedy (1977)	Adult (n=20)	Pneumonia, CHF, post-op, cardiac bypass surgery, cardiac valve surgery, trauma	Unclear	Unblinded
Jabour (1991)	Adult general (n=38)	COPD, pneumonia, lung injury, postop, neuromuscular, neurological, airway protection, trauma,	Yes	Likely unblinded
Sassoon (1993)	Adult general (n=45)	COPD, pneumonia, CHF, neurological	Unclear	Fully blinded
Frutos (1995)	Adult general (n=73)	COPD, CHF, post-op, neuromuscular, neurological, trauma	Unclear	Likely unblinded
Chatila (1996b)	Adult general (n=100)	COPD, asthma, pneumonia, CHF, neurological, airway protection	Yes	Unblinded
Dojat (1996)	Adult general (n=38)	COPD, asthma, pneumonia, CHF, hemodynamic instability, post-op	Yes	Likely unblinded
Saura (1996b)	Adult general (n=30)	COPD, trauma	Unclear	Likely unblinded
Chao (1997)	Adult general (n=174)	COPD	Yes	Likely unblinded
Del Rosario (1997)	Adult general (n=49)	COPD, pneumonia, CHF, neurological	Yes	Likely unblinded
Successful Extubation
Author (year)	ICU Population	Diagnoses	Representative Sample	Blinding of Outcome Assessor
Tahvanainen (1983)	Adult (n=47)	CHF, acute lung ingury, neuromuscular	Yes	Likely unblinded
Adderley (1987)	Pediatric (n=28)	Croup	No: according to case mix	Unblinded
Kline (1987)	Adult general (n=50)	COPD, pneumonia, post-op, cardiac bypass surgery, cardiac valve surgery	Yes	Partial
Fisher (1992)	Adult general (n=72)	COPD, asthma, cardiac bypass surgery, trauma	Unclear	Unblinded
Ochiai (1993)	Adult general (n=38)	Post-op	No: according to case mix	Likely unblinded
Yang (1993)	Adult general (n=31)	Pneumonia, CHF, lung injury, neuromuscular, airway protection	Yes	Fully blinded
Lee (1994)	Adult general (n=52)	COPD, pneumonia, CHF, neurological	Unclear	Likely unblinded
Epstein (1995)	Adult general (n=94)	COPD, asthma, pneumonia, CHF, lung injury, hemodaynamic instability, neuromuscular, neurological	Yes	Unblinded
DeHaven (1996)	Adult general (n=589)	Trauma	No: according to case mix	Likely unblinded
Mergoni (1996)	Adult general (n=51)	Hemodynamic instability, post-op, neurological, trauma	Yes	Likely unblinded
el-Khatib (1996)	Pediatric (n=50)	Asthma, pneumonia, lung injury, hemodynamic instability, post-op, neurological, airway protection, cardiac bypass surgery, cardiac valve surgery, infant RDS, trauma	Yes	Fully blinded
Ely (1996)	Adult (n=300)	COPD, asthma, pneumonia, CHF, acute lung injury, neurological	Yes	Unblinded
Epstein (1996)	Adult general (n=218)	COPD, asthma, pneumonia, CHF, hemodynamic instability, neuromuscular, neurological	Yes	Partial
Khan (1996)	Pediatric and some not reported (n=213)	Not reported	Yes	Partial
Leitch (1996)	Adult general (n=163)	COPD	Yes	Unblinded
Baumeister (1997)	Pediatric (n=47)	Asthma, pneumonia, hemodynamic instability, post-op, neurological, airway protection, congenital heart disease, trauma	Yes	Partial
Gologorskii (1997)	Adult surgical (n=127)	Post-op	No: according to case mix	Likely unblinded
Krieger (1997)	Adult general (n=49)	COPD, pneumonia, CHF, lung injury	No: according to case mix	Partial
Hilbert (1998b)	Adult (n=40)	COPD	No: according to case mix	Partial
Afessa (1999)	Adult (n=118)	COPD, asthma, pneumonia, CHF, acute lung injury, hemodynamic instability, neuromuscular	Yes	Fully blinded
Engoren (1999)	Adult (n=82)	Cardiac bypass surgery	No: according to case mix	Likely unblinded
Rady (1999)	Adult (n=11,330)	COPD, asthma, CHF, cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded
Jacob (1997)	Adult surgical (n=183)	Post-op	No: according to case mix	Unblinded
Bouachour (1996)	Adult COPD (n=26)	COPD	No: according to case mix	Fully blinded
Jubran (1997)	Adult COPD (n=31)	COPD	No: according to case mix	Partial
Farias (1998)	Pediatric (n=84)	Pneumonia, post-op, neurological, infant RDS	Yes	Fully blinded
Vallverdu (1998)	Adult general (n=217)	COPD, pneumonia, CHF, post-op, neurological, cardiac bypass surgery, cardiac valve surgery, trauma	Yes	Likely unblinded
Combination of: Successful stepwise decrease in level of mechanical support, spontaneous breathing test prior to extubation, and trial of extubation
Author (year)	ICU Population	Diagnoses	Representative Sample	Blinding of Outcome Assessor
Amoateng-Adjepong (1997)	Adult general (n=60)	COPD, pneumonia, CHF, neurological	Yes	Partial
Weaned and successfully extubated at any time
McDonald (1988)	Adult general (n=30)	COPD, pneumonia, CHF, lung injury, hemodynamic instability, postop, neurological, airway protection, cardiac bypass surgery	Yes	Partial
Menzies (1989)	Adult general (n=95)	COPD, asthma, pneumonia, CHF, lung injury, postop, neurological, neuromuscular, cardiac bypass surgery, cardiac valve surgery, congenital heart disease	Yes	Partial
Shikora (1990)	Adult general (n=20)	Postop, cardiac bypass surgery, cardiac valve surgery	Yes	Unblinded
Nava (1994b)	Adult COPD (n=42)	COPD	No: according to case mix	Likely unblinded
Saldias (1996)	Adult postcardiac surgery (n=230)	Post-op, cardiac bypass surgery, cardiac valve surgery, congenital heart disease	Yes	Likely unblinded
Moody (1997)	Adult COPD (n=27)	COPD	No: according to case mix	Partial
Duration of ventilation in COPD patients
Thorens (1995)	Adult general (n = 87)	COPD	No: according to case mix	Fully blinded
Duration of ventilation in cardiac patients
Peters (1979)	Adult postcardiac surgery (n=49)	Cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Partial
Kanter (1986)	Pediatric (n=140)	Cardiac valve surgery, congenital heart disease	No: according to case mix	Likely unblinded
Ingersoll (1991)	Adult general (n=47)	Neuromuscular, cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded
Goodnough-Hanneman (1994)	Adult postcardiac surgery (n=162)	Cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded
Arom (1995)	Adult general (n=645)	COPD, cardiac bypass surgery	No: according to case mix	Likely unblinded
Habib (1996)	Adult general (n=507)	COPD, CHF, cardiac bypass surgery	No: according to case mix	Likely unblinded
Bando (1997)	Adult general (n=586)	CHF, cardiac bypass surgery, cardiac valve surgery	Yes	Partial
Doering (1997)	Adult postcardiac surgery (n=62)	Cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Unblinded
Doering (1998)	Adult general (n=116)	COPD, cardiac bypass surgery	Yes	Partial
London (1998)	Adult postcardiac surgery (n=299)	COPD, postop, neurological, cardiac bypass surgery, cardiac valve surgery	No: according to case mix	Likely unblinded

Evidence Table 13. Results of individual observational studies of weaning predictors

Author, Year	Number of Patients	Outcome	Predictor	Predictive Power	P Value
Oh, 1991	20	successful mechanical support	weight CHF/pulmonary edema COPD/asthma oxygen consumption age sex (proportion female)	mean ± sd of success: 56.52 ± 9.43 mean ± sd of failure: 54.24 ± 9.79 sensitivity: 92.3 specificity: 14.3 sensitivity: 92.3 specificity: 28.6 mean ± sd of success: 233.31 ± 58.96 mean ± sd of failure: 205.43 ± 44.29 mean ± sd of success: 51.46 ± 17.88 mean ± sd of failure: 67.57 ± 6.8 sensitivity: 23.1 specificity: 57.1
Linton, 1994	27	successful mechanical support	minute ventilation respiratory rate tidal volume P_0.1 peak inspiratory pressure PaCO₂ PaO₂ vital capacity end tidal CO₂	median of success: 8.8 median of failure: 8.1 median of success: 14.0 median of failure: 12.0 median of success: 542 median of failure: 602 median of success: 0.46 median of failure: 2.30 median of success: 23.9 median of failure: 31.7 median of success: 4.25 median of failure: 4.55 median of success: 20.5 median of failure: 12.1 median of success: 1100 median of failure: 900 median of success: 3.61 median of failure: 3.91
Stroetz, 1995	31	successful mechanical support -PS	heart rate mean blood pressure respiratory rate VD/V_T = dead space severity of obstruction Vp10 PI_max compliance dyspnea Borg scale SaO₂ PaO₂/FiO₂ end tidal CO₂ clinical prediction of success age	mean ± se of success: 89.6 ± 10.2 mean ± se of failure: 89.9 ± 15.8 mean ± se of success: 89.2 ± 14 mean ± se of failure: 88.6 ± 14.4 mean ± se of success: 14.7 ± 3.4 mean ± se of failure: 19.8 ± 5 mean ± se of failure: 0.64 ± 0.32 mean of success: 0.6 mean of failure: 0.54 mean ± se of success: 42 ± 0.2 mean ± se of failure: 28 ± 0.22 mean ± se of success: 0.08 ± 0.04 mean ± se of failure: 0.05 ± 0.02 mean ± se of success: 9.7 ± 2.4 mean ± se of failure: 9.3 ± 2.6 mean ± se of success: 97.6 ± 1.8 mean ± se of failure: 98 ± 2.2 mean ± se of success: 288 ± 86 mean ± se of failure: 237 ± 116 mean ± se of success: 33.5 ± 8.2 mean ± se of failure: 34.9 ± 7.4 sensitivity: 35 specificity: 79 mean ± se of success: 68 ± 8 mean ± se of failure: 65 ± 10	>0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05 >0.05
Rivera, 1997	40	successful mechanical support - PS - IMV - other	minute ventilation <10 respiratory rate <22 tidal volume rapid shallow breathing index <65 P_0.1 <4.5 pressure time product - threshold: 275 Paw mean dynamic compliance intrinsic PEEP extrinsic PEEP total positive end expiratory pressure inspiratory time/total respiratory cycle	sensitivity: 90 specificity: 50 sensitivity: 84 specificity: 76 mean ± sd of success: 0.41 ± 0.1 mean ± sd of failure: 0.38 ± 0.09 sensitivity: 90 specificity: 80 sensitivity: 100 specificity: 100 sensitivity: 100 specificity: 80 mean ± sd of success: 8.9 ± 4.7 mean ± sd of failure: 10.4 ± 4.6 mean ± sd of success: 81 ± 34 mean ± sd of failure: 72 ± 24 mean ± sd of success: 1.6 ± 0.8 mean ± sd of failure: 5.8 ± 2.4 mean ± sd of success: 2.5 ± 0.3 mean ± sd of failure: 3 ± 0.9 mean ± sd of success: 6.9 ± 2.3 mean ± sd of failure: 8.9 ± 2.7 mean ± sd of success: 37 ± 7 mean ± sd of failure: 42 ± 5	<0.001 <0.02
Hilberman, 1976	124	successful discontinuation - T-piece	duration mechanical ventilation (hours) mean blood pressure VD/VT = dead space vital capacity in cc/kg vital capacity % predicted VC % predicted FeV₁ negative inspiratory force inspiratory resistance compliance PaO₂ pH PaCO₂ DLCO% cardiac index before bypass	mean ± sd of success: 13.4 ± 11.5 mean ± sd of failure: 23.7 ± 26.9 mean ± sd of success: 87.4 ± 29.6 mean ± sd of failure: 80.2 ± 14.7 mean ± sd of success: 0.53 ± 0.36 mean ± sd of failure: 0.52 ± 0.21 mean ± sd of success: 18.3 ± 7.2 mean ± sd of failure: 11.9 ± 4 mean ± sd of success: 1.3 ± 0.63 mean ± sd of failure: 0.79 ± 0.3 mean ± sd of success: 90.7 ± 13.7 mean ± sd of failure: 71.3 ± 21.9 mean ± sd of success: 75.4 ± 9.3 mean ± sd of failure: 75.8 ± 9.8 mean ± sd of success: 30.7 ± 8.8 mean ± sd of failure: 24.3 ± 9.4 mean ± sd of success: 7.2 ± 2.7 mean ± sd of failure: 9.1 ± 2.6 mean ± sd of success: 0.05 ± 0.01 mean ± sd of failure: 0.04 ± 0.02 mean ± sd of success: 364 ± 80 mean ± sd of failure: 243 ± 93 mean ± sd of success: 7.47 ± 0.06 mean ± sd of failure: 7.46 ± 0.07 mean ± sd of success: 35.2 ± 4.9 mean ± sd of failure: 36.6 ± 7.6 mean ± sd of success: 98.9 ± 1.7 mean ± sd of failure: 104.6 ± 21.3 mean ± sd of success: 2.6 ± 0.8 mean ± sd of failure: 2.1 ± 0.6	0.07 0.11 0.84 <0.01 <0.01 <0.01 0.88 0.01 <0.01 0.02 0.29 0.67 0.37 0.34 0.03
Kennedy, 1977	20	successsful discontinuation assessment - T-piece	heart rate pH PaCO₂ cardiac index left atrial pressure	mean ± se of success: 97 ± 9 mean ± se of failure: 89 ± 4 mean ± se of success: 7.44 ± 0.02 mean ± se of failure: 7.47 ± 0.02 mean ± se of success: 36 ± 1 mean ± se of failure: 40 ± 2 mean ± se of success: 3.4 ± 0.4 mean ± se of failure: 2.5 ± 0.2 mean ± se of success: 9 ± 3 mean ± se of failure: 14 ± 2	<0.05
Jabour, 1991	38	successsful discontinuation assessment - other	minute ventilation, expressed in ml/kg respiratory rate VE/V_T tidal volume expressed in ml/kg PI_max Pbreath/NIP pbreath pressure time index dynamic characteristics PaCO₂ weaning index (PTI x VE/V_t) inspiratory time/total respiratory cycle sex (proportion female)	mean ± sd of success: 136 ± 39 mean ± sd of failure: 185 ± 53 mean ± sd of success: 26.2 ± 8.3 mean ± sd of failure: 30.3 ± 7.5 mean ± sd of success: 25 ± 11 mean ± sd of failure: 42 ± 16 mean ± sd of success: 5.9 ± 1.7 mean ± sd of failure: 4.8 ± 1.7 mean ± sd of success: 49 ± 11 mean ± sd of failure: 35 ± 15 mean ± sd of success: 0.31 ± 0.1 mean ± sd of failure: 0.39 ± 0.14 mean ± sd of success: 14.5 ± 4.4 mean ± sd of failure: 12.7 ± 4.9 mean ± sd of success: 0.12 ± 0.03 mean ± sd of failure: 0.17 ± 0.07 mean ± sd of success: 26.5 ± 5.5 mean ± sd of failure: 26 ± 6.3 mean ± sd of success: 41.7 ± 13.1 mean ± sd of failure: 48.6 ± 8.7 sensitivity: 95 specificity: 96 mean ± sd of success: 0.4 ± 0.06 mean ± sd of failure: 0.43 ± 0.08 sensitivity: 43.8 specificity:50	<0.005 <0.001 <0.05 <0.005 <0.05 <0.02
Sassoon, 1993	45	successsful discontinuation assessment - CPAP	minute ventilation <12 respiratory rate <38 tidal volume >325 rapid shallow breathing occlusion pressure index <450 rapid shallow breathing index <100 PI_max >20 P_0.1 <5.5 effective inspiratory impedance <10	sensitivity: 40 specificity: 50 sensitivity: 97 specificity: 30 sensitivity: 94 specificity: 40 sensitivity: 97 specificity: 60 sensitivity: 97 specificity: 40 sensitivity: 91 specificity: 30 sensitivity: 97 specificity: 40 sensitivity: 89 specificity: 40
Frutos, 1995	73	successsful discontinuation assessment - T-piece	admission APACHE duration of mechanical ventilation (days) COPD/asthma coma heart rate systolic blood pressure respiratory rate tidal volume expressed in ml/kg negative inspiratory force pH age	mean ± sd of success: 19.1 ± 7 mean ± sd of failure: 17.6 ± 7 mean ± sd of success: 6 ± 5.1 mean ± sd of failure: 11.4 ± 5 sens: 76.2 spec: 30 sens: 92.1 spec: 10 mean ± sd of success: 94.1 ± 17.7 mean ± sd of failure: 101.8 ± 11.1 mean ± sd of success: 132.6 ± 23.5 mean ± sd of failure: 147 ± 21 mean ± sd of success: 24.1 ± 5.3 mean ± sd of failure: 30.4 ± 5.5 mean ± sd of success: 6.8 ± 1.8 mean ± sd of failure: 6.6 ± 1.9 mean ± sd of success: 34.6 ± 13.9 mean ± sd of failure: 31.7 ± 19.9 mean ± sd of success: 7.41 ± 0.04 mean ± sd of failure: 7.41 ± 0.03 mean ± sd of success: 58.6 ± 18.7 mean ± sd of failure: 46 ± 24.2	0.53 <0.05 0.2 0.1 <0.01 0.7 0.62 0.99 0.13
Chatila, 1996b	100	successsful discontinuation assessment	minute ventilation <15 minute volume at time 0 <10 l/min rapid shallow breathing index <100 negative inspiratory force <20 negative inspiratory force <30	sens: 97 spec: 11 sens: 79 spec: 32 sens: 98 spec: 59 sens: 90 spec: 26 sens: 67 spec: 69
Dojat, 1996	38	successsful discontinuation assessment - T-piece	admission SAPS <15 duration mechanical ventilation (hours) - threshold: 10 respiratory rate <30 tidal volume >325 successful 2-hour T-piece trial rapid shallow breathing index <100 negative inspiratory force <-25 Knowledge-based system	sens: 76.5 spec: 33.3 sens: 70.6 spec: 61.9 sens: 100 spec: 76.2 sens: 52.9 spec: 76.2 sens: 100 spec: 76 sens: 94.1 spec: 81 sens: 94.1 spec: 23.5 sens: 100 spec: 90.5
Saura, 1996b	30	successsful discontinuation assessment - CPAP	respiratory rate tidal volume PaO₂ pH PaCO₂ end tidal CO₂	mean ± se of success: 21 ± 1 mean ± se of failure: 23 ± 2 mean ± se of success: 450 ± 20 mean ± se of failure: 440 ± 30 mean ± se of success: 97 ± 6 mean ± se of failure: 102 ± 11 mean ± se of success: 7.47 ± 0.01 mean ± se of failure: 7.46 ± 0.02 mean ± se of success: 38 ± 2 mean ± se of failure: 38 ± 6 mean ± se of success: 33 ± 1 mean ± se of failure: 35 ± 4
Chao, 1997	174	successsful discontinuation assessment - other	patient-ventilator trigger asynchrony	sensitivity: 96.7 specificity: 19.3
Del Rosario, 1997	49	successsful discontinuation assessment - T -peice	duration of mechanical ventilation (d) heart rate mean blood pressure minute ventilation respiratory rate tidal volume rapid shallow breathing index PI_max P_0.1 inspiratory flow rate (V_t/T_i) intrinsic PEEP inspiratory time/total respiratory cycle age	mean ± sd of success: 6.8 ± 7.3 mean ± sd of failure: 13.5 ± 21.1 mean ± se of success: 100.1 ± 2.3 mean ± se of failure: 94.4 ± 4.3 mean ± se of success: 96.2 ± 2.8 mean ± se of failure: 82.9 ± 4.3 mean ± se of success: 12.8 ± 0.6 mean ± se of failure: 13.9 ± 1.6 mean ± se of success: 25.1 ± 1.1 mean ± se of failure: 35.2 ± 3.4 mean ± se of success: 530 ± 28 mean ± se of failure: 436 ± 62 mean ± se of success: 54.5 ± 4.4 mean ± se of failure: 112.7 ± 27.3 mean ± se of success: 43.4 ± 3.4 mean ± se of failure: 33.2 ± 4.4 mean ± se of success: 3.2 ± 0.2 mean ± se of failure: 5.2 ± 1.3 mean ± se of success: 0.56 ± 0.02 mean ± se of failure: 0.59 ± 0.07 mean ± se of success: 2 ± 0.4 mean ± se of failure: 2 ± 0.5 mean ± se of success: 0.39 ± 0.01 mean ± se of failure: 0.39 ± 0.02 mean ± sd of success: 63.1 ± 10 mean ± sd of failure 72 ± 7	<0.005
Delooz, 1976	41	successsful discontinuation assessment	heart rate mean blood pressure gross alveolar ventilation minute ventilation respiratory rate tidal volume VD/V_t physiologic shunt PAO₂PaO₂ PaO₂ pH CaO₂CvO₂ PaCO₂ cardiac index right atrial pressure left atrial pressure pulmonary artery pressure systemic vascular resistance index pulmonary vascular resistance index	mean ± sd of success: 96 ± 14 mean ± sd of failure: 92 ± 26 mean ± sd of success: 85.7 ± 13.9 mean ± sd of failure: 84.3 ± 15 mean ± sd of success: 229 ± 61.1 mean ± sd of failure: 160.8 ± 42.7 mean ± sd of success: 5.451 ± 1.468 mean ± sd of failure: 4.671 ± 1.224 mean ± sd of success: 25.8 ± 6.6 mean ± sd of failure: 29.5 ± 6.7 mean ± sd of success: 469 ± 151 mean ± sd of failure: 371 ± 111 mean ± sd of success: 154 ± 51.3 mean ± sd of failure: 153.2 ± 57.2 mean ± sd of success: 0.11 ± 0.05 mean ± sd of failure: 0.12 ± 0.04 mean ± sd of success: 208 ± 75 mean ± sd of failure: 226 ± 71 mean ± sd of success: 200 ± 84 mean ± sd of failure: 180 ± 74 mean ± sd of success: 7.41 ± 0.04 mean ± sd of failure: 7.38 ± 0.05 mean ± sd of success: 6.7 ± 1.3 mean ± sd of failure: 6.5 ± 2.4 mean ± sd of success: 38 ± 3.4 mean ± sd of failure: 41.7 ± 6.9 mean ± sd of success: 2.47 ± 0.67 mean ± sd of failure: 2.57 ± 1.7 mean ± sd of success: 5.2 ± 4.2 mean ± sd of failure: 11 ± 6.2 mean ± sd of success: 8.2 ± 3.2 mean ± sd of failure: 10.8 ± 3.8 mean ± sd of success: 24 ± 11.6 mean ± sd of failure: 31.1 ± 13.8 mean ± sd of success: 1833 ± 677 mean ± sd of failure: 1904 ± 825 mean ± sd of success: 507 ± 287 mean ± sd of failure: 810 ± 648
Tahvanainen, 1983	47	successful extubation - 24.1-48 h	duration of mechanical ventilation heart rate mean blood pressure maximum voluntary ventilation mean minute ventilation respiratory rate tidal volume VD/V_t = dead space vital capacity PI_max SaO₂ PaO₂ pH VCO₂ VO₂ vent postoperative hemoglobin age	mean ± se of success: 4.7 ± 0.5 mean ± se of failure: 6 ± 1.2 mean ± se of success: 98 ± 2.9 mean ± se of failure: 91.9 ± 3.2 mean ± se of success: 96.9 ± 2.4 mean ± se of failure: 99.2 ± 7.1 mean ± se of success: 12.6 ± 0.5 mean ± se of failure: 11.5 ± 1.2 mean ± se of success: 6.16 ± 0.55 mean ± se of failure: 5.96 ± 0.66 mean ± se of success: 23.6 ± 1.2 mean ± se of failure: 19.6 ± 2 mean ± se of success: 270 ± 20 mean ± se of failure: 310 ± 30 mean ± se of success: 42 ± 2 mean ± se of failure: 46 ± 4 mean ± sd of success: 0.8 ± 0.05 mean ± sd of failure: 0.76 ± 0.09 mean ± se of success: 35.7 ± 1.6 mean ± se of failure: 39 ± 1.4 mean ± se of success: 96 ± 0.5 mean ± se of failure: 95.6 ± 0.3 mean ± se of success: 93.6 ± 3.6 mean ± se of failure: 78.8 ± 8.3 mean ± se of success: 7.43 ± 0.01 mean ± se of failure: 7.41 ± 0.02 mean ± se of success: 144 ± 7 mean ± se of failure: 145 ± 9 mean ± se of success: 161 ± 8 mean ± se of failure: 174 ± 13 mean ± se of success: 11.9 ± 0.2 mean ± se of failure: 11 ± 0.4 mean ± se of success: 52.6 ± 2.4 mean ± se of failure: 52.9 ± 5.1	0.318 0.32 0.575 0.384 0.805 0.135 0.356 0.332 0.71 0.339 0.575 0.072 0.272 0.943 0.492 0.082 0.976
Adderley, 1987	28	successful extubation	leak test in neonates	sensitivity: 75 specificity: 62.5
Kline, 1987	50	successful extubation - 24.1-48 h	pneumonia postcardiac resuscitation endocarditis post heart surgery postabdominal surgery postthoracic surgery lung cancer COPD/asthma respiratory rate tidal volume PI_max change in intrapleural pressure change in intrapleural pressure/NIF change in P_t/NIF - threshold: 0.4 inspiratory resistance dynamic elastance	sensitivity: 96.6 specificity: 0 sensitivity: 96.6 specificity: 9.5 sensitivity: 96.6 specificity: 4.8 sensitivity: 58.6 specificity: 19 sensitivity: 79.3 specificity: 14.3 sensitivity: 93.1 specificity: 14.3 sensitivity: 96.6 specificity: 0 sensitivity: 82.8 specificity: 28.6 mean ± sd of success: 21.5 ± 4.8 mean ± sd of failure: 22.7 ± 5.4 mean ± sd of success: 0.34 ± 0.08 mean ± sd of failure: 0.4 ± 0.08 mean ± sd of success: 36.1 ± 10.1 mean ± sd of failure: 29 ± 7.6 mean ± sd of success: 11.2 ± 2.9 mean ± sd of failure: 15.2 ± 4.5 mean ± sd of success: 0.32 ± 0.07 mean ± sd of failure: 0.53 ± 0.1 sensitivity: 93.1 specificity: 100 mean ± sd of success: 9.1 ± 3.5 mean ± sd of failure: 9.7 ± 6.3 mean ± sd of success: 23.7 ± 8.7 mean ± sd of failure: 27.7 ± 10.1
Fisher, 1992	72	successful extubation - 12.1-24 h	cuff leak test	sensitivity: 88.7 specificity: 100
Ochiai, 1993	38	successful extubation - 12.1-24 h	weight minute ventilation adjusted for weight respiratory rate tidal volume expressed in ml/kg VD/V_t % predicted VC % predicted FeV₁ inspiratory flow rate (V_t/T_i) PaO₂ pH PaCO₂ end tidal CO₂ inspiratory time/total respiratory cycle CO₂ produced (VCO₂) age sex (proportion female)	mean ± sd of success: 55.5 ± 6.4 mean ± sd of success: 147.2 ± 49.4 mean ± sd of failure: 140.3 ± 48.8 mean ± sd of success: 14.4 ± 2.9 mean ± sd of failure: 14.5 ± 5.6 mean ± sd of success: 9.67 ± 2.94 mean ± sd of failure: 10.08 ± 1.97 mean ± sd of success: 36.6 ± 5.1 mean ± sd of failure: 33.4 ± 8.3 mean ± sd of success: 95.9 ± 18.7 mean ± sd of failure: 105.7 ± 10.7 mean ± sd of success: 76.1 ± 6.7 mean ± sd of failure: 71.9 ± 5.2 mean ± sd of success: 7.97 ± 2.69 mean ± sd of failure: 8.46 ± 1.47 mean ± sd of success: 124.4 ± 22 mean ± sd of failure: 119.2 ± 26.9 mean ± sd of success: 7.41 ± 0.03 mean ± sd of failure: 7.43 ± 0.05 mean ± sd of success: 39.7 ± 4 mean ± sd of failure: 39.1 ± 6.3 mean ± sd of success: 36.8 ± 3.9 mean ± sd of failure: 37.6 ± 6.4 mean ± sd of success: 0.3 ± 0.06 mean ± sd of failure: 0.28 ± 0.09 mean ± sd of success: 4.7 ± 1.3 mean ± sd of failure: 4.6 ± 1.1 mean ± sd of success: 60.9 ± 8.1 mean ± sd of failure: 62.6 ± 7.3 sensitivity: 15.8 specificity: 89.5
Yang, 1993	31	successful extubation - 12.1-24 h	neuromuscular disorder pneumonia ARDS CHF/pulmonary edema minute ventilation minute ventilation <15 respiratory rate respiratory rate <38 tidal volume tidal volume >325 rapid shallow breathing <100 AND NIP/PI_max <0.03 rapid shallow breathing index rapid shallow breathing index <100 Negative inspiratory force PI_max - threshold: 15 NIP/ PI_max NIP/PI_max <0.3 age sex (proportion female)	sensitivity: 62.5 specificity: 20 sensitivity: 81.3 specificity: 20 sensitivity: 93.8 specificity: 20 sensitivity: 81.3 specificity: 6.7 mean ± se of success: 13 ± 0.67 mean ± se of failure: 10.64 ± 1.26 sensitivity: 81 specificity: 20 mean ± se of success: 28 ± 1.94 mean ± se of failure: 36.93 ± 2.92 sensitivity: 88 specificity: 47 mean ± se of success: 0.497 ± 0.053 mean ± se of failure: 0.29 ± 0.028 sensitivity: 100 specificity: 67 sensitivity: 81 specificity: 93 mean ± se of success: 65.26 ± 7.11 mean ± se of failure: 143.3 ± 15.03 sensitivity: 94 specificity: 73 mean ± se of success: 11.48 ± 1.25 mean ± se of failure: 14.32 ± 2.31 mean ± se of success: 47.77 ± 4.48 mean ± se of failure: 40.16 ± 4.55 sensitivity: 100 specificity: 13 mean ± se of success: 0.26 ± 0.03 mean ± se of failure: 0.36 ± 0.04 sensitivity: 75 specificity: 67 mean ± sd of success: 55 ± 3.5 mean ± sd of failure: 59 ± 5.3 sensitivity: 31.3 specificity: 60	0.11 <0.05 <0.01 <0.01 0.28 0.24 <0.05
Lee, 1994	52	successful extubation - 12.1-24 h	duration of mechanical ventilation (d) rapid shallow breathing index <105 age	mean ± sd of success: 4.6 ± 3.9 mean ± sd of failure: 9.6 ± 6.8 sensitivity: 72 specificity: 11 mean ± sd of success: 55.2 ± 18.8 mean ± sd of failure: 52.8 ± 19.6	0.004 0.73
Epstein, 1995	94	successful extubation - other	rapid shallow breathing index <100	sensitivity: 92 specificity: 22
DeHaven, 1996	589	successful extubation	respiratory rate <30	sensitivity: 82.1 specificity: 17.4
el-Khatib, 1996	50	successful extubation - 24.1-48 h	NIP/PI_max NIP/PI_max <0.3 NIP/PI_max <0.4 sex (proportion female)	mean ± sd of success: 0.36 ± 0.14 mean ± sd of failure: 0.45 ± 0.1 sensitivity: 33.3 specificity: 90.9 sensitivity: 62 specificity: 63 sensitivity: 46.2 specificity: 54.5
Ely, 1996	300	successful extubation - 24.1-48 hrs	pass daily screening tests	sens: 88 spec: 67
Epstein, 1996	218	successful extubation - other	rapid shallow breathing index <100 sex (proportion female)	sensitivity: 88.6 specificity: 23.5 sensitivity: 38.6 specificity: 67.6
Khan, 1996	213	successful extubation - >48hrs	duration of mechanical ventilation (d) respiratory rate standardized to age - threshold: 1 - threshold: 2 respiratory rate V_t/T_i - threshold: 14 - threshold: 7 tidal volume tidal volume expressed in ml/kg - threshold: 6 - threshold: 4 RSBI standardized to body weight <8 - threshold: 4 Negative inspiratory force PI_max - threshold: 5 - threshold: 10 NIP/PI_max peak inspiratory pressure - threshold: 25 - threshold: 30 inspiratory flow rate dynamic compliance Cdyn standardized to body weight - threshold: 0.9 - threshold: 0.4 FiO₂ PaO₂ pH HCO₃ PaCO₂ oxygenation index oxygenation index - threshold: 1.5 - threshold: 5 CROP Index - threshold: 0.2 - threshold: 0.5 age	mean ± se of success: 5 ± 0.4 mean ± se of failure: 5.2 ± 0.6 sensitivity: 70.5 specificity: 33.3 sensitivity: 42.8 specificity: 66.7 beta P value: 0.768 sensitivity: 36.3 specificity: 81.3 sensitivity: 87.7 specificity: 25 beta P value: 0.01 sensitivity: 48.5 specificity: 71.9 specificity: 28.1 sensitivity: 63.8 specificity: 55.9 beta P value: 0.34 sensitivity: 24.1 specificity: 76.5 beta P value: 0.34 beta P value: 0.412 beta P value: 0.536 sensitivity: 8.2 specificity: 97.1 beta P value: 0.012 sensitivity: 98.2 specificity: 11.8 beta P value: 0.012 beta P value: 0.791 sensitivity: 44.3 specificity: 82.4 beta P value: 0.001 sensitivity: 77 specificity: 47.1 beta P value: 0.001 beta P value: 0.004 beta P value: 0.116 sensitivity: 5.9 specificity: 97.1 sensitivity: 18.2 specificity: 85.3 beta P value: 0.018 mean ± se of success: 105.3 ± 4.3 mean ± se of failure: 99.8 ± 6.8 mean ± se of success: 7.43 ± 0.01 mean ± se of failure: 7.41 ± 0.38 mean ± se of success: 26.4 ± 0.3 mean ± se of failure: 26.5 ± 0.8 mean ± se of success: 40.5 ± 0.6 mean ± se of failure: 42.3 ± 1.4 beta P value: 0.012 sensitivity: 21 specificity: 84.8 sensitivity: 93 specificity: 18.2 sensitivity: 55.8 specificity: 46.9 beta P value: 0.41 sensitivity: 18.6 specificity: 84.4 beta P value: 0.41 mean ± se of success: 3.05 ± 0.35 mean ± se of failure: 4.4 ± 1.01	0.8 0.768 0.01 0.34 0.34 0.412 0.536 0.012 0.012 0.791 <0.001 <0.001 0.004 0.116 0.018 0.6 0.9 0.23 0.012 0.41 0.41 0.14
Leitch, 1996	163	successful extubation -12.1-24 h	minute volume <10 prior to CPAP/PS vital capacity <10 rapid shallow breathing index <100 PI_max >20	sensitivity: 50 specificity: 67 sensitivity: 72 specificity: 0 sensitivity: 96.3 specificity: 0 sensitivity: 97 specificity: 0
Mergoni, 1996	51	successful extubation -12.1-24 H	minute ventilation < 10 respiratory rate <30 rapid shallow breathing index <105 PI_max >30 P_0.1/MIP <0.14 inspiratory quotient k(TV/C_dyo)/MIP X T_i/T_x - threshold: 0.19 weaning index PTI X VE40/V_t - threshold: 4 CROP Index - threshold: 13	sens: 60 spec: 53 sens: 70 spec: 66 sens: 65 spec: 58 sens: 73 spec: 40 sens: 85 spec: 36 sens: 94 spec: 12 sens: 69 spec: 47 spec: 70 sens: 63
Baumeister, 1997	47	successful extubation - 24.1-48 h	pneumonia congential heart disease RSBI standardized to body weight <11 CROP Index standardized to weight - threshold: 0.1 sex (proportion female)	sensitivity: 89.5 specificity: 22.2 sensitivity: 60.5 specificity: 55.6 sensitivity: 78.9 specificity: 77.9 sensitivity: 100 specificity: 100 sensitivity: 47.4 specificity: 55.6
Gologorskii, 1997	127	successful extubation	heart rate minute ventilation respiratory rate tidal volume rapid shallow breathing index negative inspiratory force inspiratory resistance dynamic compliance physiologic shunt PaO₂ PaO₂/FiO₂ pH PaCO₂	sens: 79 spec: 58 sens: 66 spec: 66 sens: 70 spec: 72 sens: 73 spec: 75 sens: 84 spec: 83 sens: 68 spec: 62 sens: 74 spec: 77 sens: 77 spec: 80 sens: 80 spec: 61 sens: 74 spec: 61 sens: 86 spec: 46 sens: 84 spec: 54 sens: 70 spec: 55
Krieger, 1997	49	successful extubation > 48 h	duration of mechanical ventilation (d) pneumonia ARDS CHF/pulmonary edema COPD/asthma minute ventilation respiratory rate tidal volume rapid shallow breathing index <105 rapid shallow breathing index <130 PI_max peak inspiratory pressure static compliance intrinsic PEEP extrinsic PEEP FiO₂ PaO₂/PAO₂ pH PaCO₂ age	mean ± sd of success: 5.5 ± 6 mean ± sd of failure: 13 ± 11 sensitivity: 63.2 sensitivity: 89.5 specificity: 9.1 sensitivity: 76.3 specificity: 27.3 sensitivity: 84.2 specificity: 18.2 mean ± sd of success: 6.4 ± 2.5 mean ± sd of failure: 6.1 ± 2.1 mean ± sd of success: 22 ± 7 mean ± sd of failure: 28 ± 5 mean ± sd of success: 0.31 ± 0.13 mean ± sd of failure: 0.22 ± 0.76 sensitivity: 74 specificity: 73 sensitivity: 92 specificity: 57 mean ± sd of success: 43 ± 11 mean ± sd of failure: 35 ± 11 mean ± sd of success: 25 ± 8 mean ± sd of failure: 29 ± 7.5 mean ± sd of success: 0.049 ± 0.014 mean ± sd of failure: 0.04 ± 0.014 mean ± sd of success: 0.53 ± 1.3 mean ± sd of failure: 1.5 ± 2.8 mean ± sd of success: 3.82 ± 1.5 mean ± sd of failure: 4 ± 1.18 mean ± sd of success: 0.4 ± 0.06 mean ± sd of failure: 0.38 ± 0.06 mean ± sd of success: 0.53 ± 0.18 mean ± sd of failure: 0.49 ± 0.16 mean ± sd of success: 7.46 ± 0.05 mean ± sd of failure: 7.44 ± 0.04 mean ± sd of success: 36 ± 7 mean ± sd of failure: 45 ± 7 mean ± sd of success: 79 ± 6 mean ± sd of failure: 80 ± 7	<0.05 <0.05 <0.05
Hilbert, 1998b	40	successful extubation - other	respiratory rate rapid shallow breathing index P_0.1 effective inspiratory impedance PaO₂ PaO₂/FiO₂ pH HCO₃ PaCO₂ age	mean ± sd of success: 24 ± 5 mean ± sd of failure: 25 ± 5 mean ± sd of success: 60 ± 2 mean ± sd of failure: 66 ± 28 mean ± sd of success: 2.4 ± 0.9 mean ± sd of failure: 2.9 ± 0.7 mean ± sd of success: 5.2 ± 1.2 mean ± sd of failure: 6.1 ± 1.3 mean ± sd of success: 59 ± 6 mean ± sd of failure: 60 ± 7 mean ± sd of success: 248 ± 62 mean ± sd of failure: 241 ± 56 mean ± sd of success: 7.42 ± 0.02 mean ± sd of failure: 7.41 ± 0.02 mean ± sd of success: 30 ± 4 mean ± sd of failure: 30 ± 3 mean ± sd of success: 58 ± 6 mean ± sd of failure: 60 ± 7 mean ± sd of success: 68 ± 10 mean ± sd of failure: 69 ± 8
Afessa, 1999	118	successful extubation - other	admission APACHE duration of mechanical ventilation (days) minute ventilation respiratory rate rapid shallow breathing index PI_max relative inspiratory effort dynamic compliance static compliance auto-PEEP PaO₂/FiO₂ weaning index A + B + G score physician prediction respiraory therapist prediction CROP Index	mean ± sd of success: 11.3 ± 5.2 mean ± sd of failure: 16.9 ± 5.5 mean ± sd of success: 10.7 ± 6.4 mean ± sd of failure: 11.8 ± 7.8 mean ± sd of success: 10.7 ± 3.4 mean ± sd of failure: 9.5 ± 4.2 mean ± sd of success: 27.4 ± 7.8 mean ± sd of failure: 28.5 ± 9.5 mean ± sd of success: 79.2 ± 41.2 mean ± sd of failure: 103 ± 62.3 mean ± sd of success: 60.8 ± 23.7 mean ± sd of failure: 45.3 ± 17.2 sens: 55 spec: 68 mean ± sd of success: 22 ± 7 mean ± sd of failure: 24 ± 7 mean ± sd of success: 35 ± 12 mean ± sd of failure: 37 ± 14 mean ± sd of success: 1 ± 2.3 mean ± sd of failure: 1.5 ± 2.5 mean ± sd of success: 441 ± 115 mean ± sd of failure: 423 ± 125 mean ± sd of success: 5.5 ± 4.4 mean ± sd of failure: 7 ± 4.9 mean ± sd of success: 53.1 ± 13.8 mean ± sd of failure: 48.8 ± 17.6 sens: 62 spec: 65 sens: 55 spec: 62 mean ± sd of success: 36.1 ± 22.7 mean ± sd of failure: 26.5 ± 17	<0.001 0.357 0.046 0.525 0.062 <0.01 0.289 0.536 0.395 0.511 0.046 0.112 0.013
Engoren, 1999	82	successful extubation	weight duration mechanical ventilation (hours) minute ventilation, expressed in ml/kg minute ventilation tidal volume tidal volume expressed in ml/kg vital capacity in cc/kg negative inspiratory force FiO₂ PaO₂ left atrial pressure arterial grafts ejection fraction cardiopulmonary bypass time age	mean ± sd of success: 85 ± 19 mean ± sd of failure: 79 ± 15 median (IQR) of success: 6 (4.7,12.7) median (IQR) of failure: 15.5 (8.2,19.5) mean ± sd of success: 0.09 ± 0.03 mean ± sd of failure: 0.11 ± 0.03 mean ± sd of success: 7.55 ± 2.31 mean ± sd of failure: 8.25 ± 2.48 mean ± sd of success: 533 ± 173 mean ± sd of failure: 457 ± 131 mean ± sd of success: 6.4 ± 1.9 mean ± sd of failure: 5.8 ± 1.3 mean ± sd of success: 15.6 ± 6.2 mean ± sd of failure: 11.5 ± 3.9 mean ± sd of success: 42 ± 8 mean ± sd of failure: 38 ± 10 mean ± sd of success: 0.53 ± 0.08 mean ± sd of failure: 0.61 ± 0.19 mean ± sd of success: 131 ± 41 mean ± sd of failure: 123 ± 52 mean ± sd of success: 20 ± 8 mean ± sd of failure: 20 ± 7 median (IQR) of success: 3 (2,4) median (IQR) of failure: 3 (2,4) mean ± sd of success: 0.55 ± 0.13 mean ± sd of failure: 0.53 ± 0.13 median (IQR) of success: 89 (68,109) median (IQR) of failure: 115 (96,147) mean ± sd of success: 61 ± 12 mean ± sd of failure: 66 ± 11	<0.05 <0.05 <0.05 <0.05 <0.1 <0.05 <0.05
Rady, 1999	11330	successful extubation - 12.1-24hrs	diabetes hypertension prior myocardial infarction peripheral vascular disease COPD/asthma smoking history creatinine preoperative blood urea nitrogen renal failure mean blood pressure cardiac index right atrial pressure prior cardiac surgery cardiac surgery: valve only cardiac surgery: CABG emergent cardiac surgery cardiac surgery: valve or CABG NYHA class III or IV preoperative intra-aortic balloon pump aortic crossclamp time total bypass time total operating room time hemodynamic instability sex (proportion female)	sens: 78.6 spec: 25.1 sens: 47.1 spec: 41.6 sens: 58.6 spec: 44.3 sens: 78.5 spec: 32.1 sens: 93.6 spec: 11.8 sens: 40.5 spec: 62.4 mean ± sd of success: 1.2 ± 0.7 mean ± sd of failure: 1.4 ± 0.9 mean ± sd of success: 19 ± 10 mean ± sd of failure: 24 ± 16 mean ± sd of success: 74 ± 16 mean ± sd of failure: 78 ± 18 mean ± sd of success: 95 ± 15 mean ± sd of failure: 92 ± 17 mean ± sd of success: 2.6 ± 0.7 mean ± sd of failure: 2.4 ± 0.7 mean ± sd of success: 10 ± 4 mean ± sd of failure: 11 ± 6 sens: 77 spec: 39.8 sens: 69.6 spec: 35.4 sens: 41.5 spec: 40.6 sens: 94.3 spec: 12.3 sens: 88.9 spec: 17.1 sens: 85.8 spec: 23.3 sens: 97.5 spec: 6.7 mean ± sd of success: 73 ± 30 mean ± sd of failure: 86 ± 43 mean ± sd of success: 108 ± 46 mean ± sd of failure: 136 ± 75 mean ± sd of success: 5.2 ± 1.5 mean ± sd of failure: 6.5 ± 3.1 sens: 99.3 spec: 3.6 sens: 28.4 spec: 69.4	<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Sahn, 1973	100	successful discontinuation assessment + extubation	minute ventilation <10 Negative inspiratory force >25	sensitivity: 96.4 specificity: 47.1 sensitivity: 100 specificity: 100
Krieger, 1989	269	successful discontinuation assessment + extubation	duration mechanical ventilation (h) minute ventilation respiratory rate tidal volume PI_max PaO₂ PaO₂/FiO₂ pH PaCO₂ age	mean ± sd of success: 62 ± 98 mean ± sd of failure: 147 ± 144 mean ± sd of success: 7.9 ± 3 mean ± sd of failure: 8.1 ± 3.2 mean ± sd of success: 22 ± 6 mean ± sd of failure: 23 ± 8 mean ± sd of success: 371 ± 149 mean ± sd of failure: 355 ± 140 mean ± sd of success: 38 ± 14 mean ± sd of failure: 32 ± 14 mean ± sd of success: 105 ± 27 mean ± sd of failure: 107 ± 32 mean ± sd of success: 280 ± 86 mean ± sd of failure: 298 ± 115 mean ± sd of success: 7.44 ± 0.05 mean ± sd of failure: 7.42 ± 0.05 mean ± sd of success: 37 ± 5 mean ± sd of failure: 38 ± 7 mean ± sd of success: 80 ± 6 mean ± sd of failure: 80 ± 6	<0.001 <0.02 <0.05
Saito, 1991	23	successful discontinuation assessment + extubation	P_0.1 <4.4	sens: 100 spec: 55.6
Yang, 1991	100	successful discontinuation assessment + extubation	minute ventilation <15 respiratory rate <38 tidal volume >325 tidal volume expressed in ml/kg >4 rapid shallow breathing index <33 rapid shallow breathing index <105 PI_max >15 dynamic compliance >22 PaO₂/PAO₂ >0.35 CROP Index -threshold: 13	sensitivity: 78 specificity: 18 sensitivity: 92 specificity: 36 sensitivity: 97 specificity: 54 sensitivity: 94 specificity: 39 sensitivity: 75 specificity: 36 sensitivity: 97 specificity: 64 sensitivity: 100 specificity: 11 sensitivity: 72 specificity: 50 sensitivity: 81 specificity: 29 sensitivity: 81 specificity: 57
Ashutosh, 1992	30	successful discontinuation assessment + extubation	minute ventilation respiratory rate tidal volume negative inspiratory force neural network analysis statistical prediction model	mean ± sd of success: 11.33 ± 4.37 mean ± sd of failure: 10.63 ± 2.4 mean ± sd of success: 22.53 ± 4.84 mean ± sd of failure: 33.27 ± 7.97 mean ± sd of success: 552.73 ± 213.69 mean ± sd of failure: 326.13 ± 99.43 mean ± sd of success: 38.8 ± 10.4 mean ± sd of failure: 21 ± 6.07 sensitivity: 100 specificity: 93.3 sensitivity: 93.3 specificity: 93.3
Gandia, 1992	30	successful discontinuation assessment + extubation	weight minute ventilation <12.5 respiratory rate <35 tidal volume >360 rapid shallow breathing index rapid shallow breathing index <96 PI_max >23 P_0.1/MIP <0.14 at 15 min P_0.1/MIP <0.14 at 60 min P_0.1/MIP <0.14 at 120 min P_0.1 <3.4 P_0.1/MIP <0.14 inspiratory effort quotient <0.19 dynamic compliance PaO₂/PAO₂ age	mean ± sd of success: 71 ± 16 mean ± sd of failure: 68 ± 10 sensitivity: 75 specificity: 64 sensitivity: 75 specificity: 82 sensitivity: 58 specificity: 75 mean ± sd of success: 71 ± 21 mean ± sd of failure: 103 ± 15 sensitivity: 83 specificity: 82 sensitivity: 75 specificity: 82 sensitivity: 82 specificity: 83 sensitivity: 82 specificity: 80 sensitivity: 82 specificity: 100 sensitivity: 75 specificity: 61 sensitivity: 1 specificity: 82 sensitivity: 100 specificity: 82 mean ± sd of success: 30 ± 5 mean ± sd of failure: 25 ± 3 mean ± sd of success: 0.43 ± 0.13 mean ± sd of failure: 0.35 ± 0.1 mean ± sd of success: 55 ± 17 mean ± sd of failure: 59 ± 11	<0.001 <0.05
Mohsenifar, 1993	29	successful discontinuation assessment + extubation	duration of mechanical ventilation (d) heart rate systolic blood pressure respiratory rate respiratory rate <38 tidal volume tidal volume > 325 rapid shallow breathing index <105 Negative inspiratory force >20 FiO₂ PaO₂ gastric intramucosal pH gastric intramucosal PCO₂ pH >7.3 or change of <0.09 change in gastric intramucosal pH change in gastric intramucosal PaCO₂ PaCO₂ age	mean ± sd of success: 6.2 ± 8 mean ± sd of failure: 7 ± 4 mean ± sd of success: 96 ± 18 mean ± sd of failure: 95 ± 17 mean ± sd of success: 128 ± 24 mean ± sd of failure: 140 ± 22 mean ± sd of success: 16 ± 4 mean ± sd of failure: 17 ± 6 sensitivity: 100 specificity: 27 mean ± sd of success: 626 ± 105 mean ± sd of failure: 608 ± 120 sensitivity: 100 specificity: 18 sensitivity: 100 specificity: 27 sensitivity: 100 specificity: 9 mean ± sd of success: 35 ± 8 mean ± sd of failure: 40 ± 7 mean ± sd of success: 95 ± 21 mean ± sd of success: 93 ± 29 mean ± sd of failure 7.45 ± 0.13 mean ± sd of failure: 7.36 ± 0.2 mean ± sd of success: 37 ± 12 mean ± sd of failure: 49 ± 23 sensitivity: 100 specificity: 100 mean of success: 0.01 mean of failure: 0.27 mean of success: 1 mean of failure: 62 mean ± sd of success: 39 ± 7 mean ± sd of failure: 40 ± 14 mean ± sd of success: 69 ± 13 mean ± sd of failure: 61 ± 20	>0.3 0.3 0.21 >0.3 >0.3 >0.3 >0.3 0.07 0.07 <0.1 <0.1 >0.3 >0.3
Capdevila, 1995	67	successful discontinuation assessment + extubation	weight admission SAPS duration of mechanical ventilation (d) minute ventilation respiratory rate tidal volume vital capacity rapid shallow breathing index rapid shallow breathing index <60 PI_max >50 P_0.1 P_0.1 <5.0 P_0.1/MIP P_0.1/MIP <0.09 Sao₂ pH inspiratory time inspiratory time/total respiratory cycle age	mean ± sd of success: 69.74 ± 13.13 mean ± sd of failure: 66.33 ± 11.69 mean ± sd of success: 11.08 ± 4.32 mean ± sd of failure: 13.25 ± 3.81 mean ± sd of success: 14.71 ± 13.2 mean ± sd of failure: 12.21 ± 6.31 mean ± sd of success: 12.61 ± 3.75 mean ± sd of failure: 12.45 ± 3.9 mean ± sd of success: 24.16 ± 7.13 mean ± sd of failure: 28.33 ± 3.98 mean ± sd of success: 527 ± 161 mean ± sd of failure: 458 ± 188 mean ± sd of success: 1.21 ± 0.68 mean ± sd of failure: 0.8 ± 0.35 mean ± sd of success: 50 ± 23 mean ± sd of failure: 69 ± 25 sensitivity: 73 specificity: 75 sensitivity: 80 specificity: 41 mean ± sd of success: 3.62 ± 1.35 mean ± sd of failure: 7.38 ± 2.67 sensitivity: 87 specificity: 91 mean ± sd of success: 0.05 ± 0.01 mean ± sd of failure: 0.14 ± 0.04 sensitivity: 98 specificity: 100 mean ± sd of success: 93 ± 3 mean ± sd of failure: 91 ± 4 mean ± sd of success: 7.41 ± 0.03 mean ± sd of failure: 7.38 ± 0.05 mean ± sd of success: 1.12 ± 0.23 mean ± sd of failure: 0.91 ± 0.28 mean ± sd of success: 0.46 ± 0.09 mean ± sd of failure: 0.48 ± 0.18 mean ± sd of success: 48.43 ± 20.23 mean ± sd of failure: 68.83 ± 7.75	>0.05 >0.05 0.694 0.069 0.067 0.027 0.018 0.001 >0.3 >0.3 >0.3 >0.3 0.07 0.07 <0.01 <0.01 0.001 0.061 0.128 >0.05 >0.05 0.0008
Bouachour, 1996	26	successful discontinuation assessment + extubation	admission SAPS duration mechanical ventilation (h) heart rate systolic blood pressure SaO₂ PaO₂ pH HCO₃ gastric intramucosal pH >7.3 gastric intramucosal PCO₂ <60d> PaCO₂ age <40	mean ± sd of success: 16 ± 3 mean ± sd of failure: 16 ± 4 mean ± sd of success: 8 ± 4 mean ± sd of failure: 11 ± 7 mean ± sd of success: 85 ± 13 mean ± sd of failure: 103 ± 22 mean ± sd of success: 134 ± 15 mean ± sd of failure: 115 ± 17 mean ± sd of success: 96 ± 2 mean ± sd of failure: 97 ± 1 mean ± sd of success: 87 ± 20 mean ± sd of failure: 88 ± 13 mean ± sd of success: 7.48 ± 0.04 mean ± sd of failure: 7.45 ± 0.06 mean ± sd of success: 33 ± 4 mean ± sd of failure: 32 ± 3 sensitivity: 100 specificity: 100 sensitivity: 95 specificity: 100 mean ± sd of success: 44 ± 6 mean ± sd of failure: 48 ± 7 sensitivity: 100 specificity: 0
Jacob, 1997	183	successful discontinuation assessment + extubation	minute ventilation <10 rapid shallow breathing index <100 negative inspiratory force <20	sens: 76 spec: 40 sens: 97 spec: 33 sens: 96 spec: 7
Jubran, 1997	31	successful discontinuation assessment + extubation	duration of mechanical ventilation (d) minute ventilation respiratory rate tidal volume/inspiratory time tidal volume rapid shallow breathing index PI_max pressure time product inspiratory resistance dynamic elastance intrinsic PEEP PaO₂ pH PaCO₂ inspiratory time inspiratory time/total respiratory cycle expiratory time tension time index age	mean ± sd of success: 10.79 ± 3.26 mean ± sd of failure: 25.12 ± 9.49 mean ± se of success: 7.98 ± 0.71 mean ± se of failure: 9.06 ± 1.32 mean ± se of success: 22.7 ± 1.6 mean ± se of failure: 34.5 ± 2.6 mean ± se of success: 329 ± 29 mean ± se of failure: 387 ± 49 mean ± se of success: 373 ± 45 mean ± se of failure: 263 ± 26 mean ± se of success: 75 ± 11 mean ± se of failure: 158 ± 20 mean ± se of success: 46.3 ± 3.1 mean ± se of failure: 41.6 ± 5.3 mean ± se of success: 158 ± 23 mean ± se of failure: 255 ± 59 mean ± se of success: 5.3 ± 1.1 mean ± se of failure: 9 ± 1.7 mean ± se of success: 9.9 ± 1.7 mean ± se of failure: 21.2 ± 3.4 mean ± se of success: 0.7 ± 0.1 mean ± se of failure: 2 ± 0.5 mean ± se of success: 100 ± 5 mean ± se of failure: 93 ± 6 mean ± se of success: 7.44 ± 0.01 mean ± se of failure: 7.43 ± 0.01 mean ± se of success: 41 ± 2 mean ± se of failure: 45 ± 2 mean ± se of success: 1.16 ± 0.09 mean ± se of failure: 0.71 ± 0.04 mean ± se of success: 0.41 ± 0.02 mean ± se of failure: 0.39 ± 0.02 mean ± se of success: 1.68 ± 0.16 mean ± se of failure: 1.29 ± 0.18 mean ± se of success: 0.05 ± 0.01 mean ± se of failure: 0.06 ± 0.01 mean ± sd of success: 70 ± 3.45 mean ± sd of failure: 67.35 ± 1.96	<0.04 <0.002 0.48 0.17 0.11 <0.01 <0.03 <0.0001
Farias, 1998	84	successful discontinuation assessment + extubation	weight duration of mechanical ventilation (days) minute ventilation, expressed in ml/kg respiratory rate tidal volume expressed in ml/kg >4 V_t in ml/kg >6.5 RSBI standardized to body RSBI standardized to body >11 PI_max PaO₂/PAO₂ PaO₂/FiO₂ age	median (IQR) of success: 7.5 (5.5,14.5) median (IQR) of success: 8 (4,13) median (IQR) of failure: 11.9 (8.9,19.6) median (IQR) of success: 245 (180,320) median (IQR) of failure: 227 (143,274) median (IQR) of success: 40 (31,50) median (IQR) of failure: 46 (36,59) sens: 94 spec: 43 median (IQR) of success: 6.8 (4.8,8) median (IQR) of success: 6.5 (4.3,8.7) median (IQR) of failure: 10.5 (8.2,14.3) sens: 86 spec: 48 median (IQR) of success: 45 (86,60) median (IQR) of failure: 37 (33,54) median (IQR) of success: 0.48 (0.4,0.6) median (IQR) of failure: 0.49 (0.46,0.51) median (IQR) of success: 295 (213,377) median (IQR) of failure: 287.6 (250.6,408) median (IQR) of success: 8 (4,33) median (IQR) of failure: 5.1 (3.4,16.4)
Vallverdu, 1998	217	successful discontinuation assessment + extubation	duration of mechanical ventilation (days) minute ventilation respiratory rate tidal volume vital capacity rapid shallow breathing occlusion pressure index rapid shallow breathing index rapid shallow breathing index <100 maximum expiratory pressure PI_max P_0.1 P_0.1 <4.5 P_0.1/MIP age	mean ± sd of success: 7 ± 7 mean ± sd of failure: 12 ± 12 mean ± sd of success: 11 ± 10 mean ± sd of failure: 10 ± 3 mean ± sd of success: 24 ± 6 mean ± sd of failure: 29 ± 8 mean ± sd of success: 432 ± 143 mean ± sd of failure: 378 ± 134 mean ± sd of success: 1.63 ± 0.64 mean ± sd of failure: 1.3 ± 0.51 mean ± sd of success: 241 ± 177 mean ± sd of failure: 452 ± 363 mean ± sd of success: 65 ± 30 mean ± sd of failure: 88 ± 44 sens: 90 spec: 36 mean ± sd of success: 53 ± 25 mean ± sd of failure: 37 ± 17 mean ± sd of success: 65 ± 21 mean ± sd of failure: 53 ± 17 mean ± sd of success: 3.6 ± 1.5 mean ± sd of failure: 5 ± 2.4 sens: 75 spec: 55 mean ± sd of success: 0.063 ± 0.032 mean ± sd of failure: 0.103 ± 0.056 mean ± sd of success: 55 ± 17 mean ± sd of failure: 59 ± 15	<0.001 <0.001 <0.01 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Thorens, 1995	87	COPD duration of ventilation	nursing index	mean difference P-value: 0.025	0.025
Peters, 1979	49	CVICU duration of ventilation	vital capacity FeV₁ maximum expiratory pressure PI_max MMEF 50-75 MMEF 75-85 cardiac surgery: valve only cardiac surgery: CABG cardiac surgery: valve or CABG	mean ± sd of success: 3.2 ± 1.1 mean ± sd of failure: 2.4 ± 0.9 mean ± sd of success: 2.1 ± 0.7 mean ± sd of failure: 1.5 ± 0.6 mean ± sd of success: 68 ± 24 mean ± sd of failure: 47 ± 26 mean ± sd of success: 60 ± 24 mean ± sd of failure: 40 ± 22 mean ± sd of success: 1.8 ± 1 mean ± sd of failure: 1.1 ± 0.6 mean ± sd of success: 0.9 ± 0.5 mean ± sd of failure: 0.5 ± 0.2 sensitivity: 14.3 specificity: 57.1 sensitivity: 71.4 specificity: 71.4 sensitivity: 14.3 specificity: 71.4	<0.01 <0.01 <0.04 <0.02 <0.01 <0.003
Kanter, 1986	140	CVICU duration of ventilation	study derived predictive index second surgical procedure preoperative mechanical ventilation cardiopulmonary bypass time aortic crossclamp time failed extubation age	sensitivity: 57 specificity: 94.7 beta P value: 0.005 beta P value: 0.05 beta P value: 0.005 beta P value: 0.01 beta P value: 0.005 beta P value: 0.005	<0.005 <0.05 <0.005 <0.01 <0.005 <0.005
Ingersoll, 1991	47	CVICU duration of ventilation	previous major surgery neuromuscular disorder pneumonia stroke (CVA) diffuse vascular disease COPD/asthma smoking history kyphoscoliosis prior lung surgery FVC % predicted VC FeV₁ FeV₁/VC % predicted FeV₁ dyspnea preoperative length of stay (d) atelectasis cough supraclavicular retraction accessory muscle use	sensitivity: 80 specificity: 33.3 sensitivity: 94.3 specificity: 0 sensitivity: 97.1 specificity: 8.3 sensitivity: 97.1 specificity: 16.7 sensitivity: 68.6 specificity: 16.7 sensitivity: 82.9 specificity: 0 sensitivity: 22.9 specificity: 83.3 sensitivity: 91.4 specificity: 33.3 sensitivity: 94.3 specificity: 8.3 mean ± sd of success: 2.5 ± 0.9 mean ± sd of failure: 2.9 ± 0.9 mean ± sd of success: 59.6 ± 15.3 mean ± sd of failure: 71.9 ± 13.9 mean ± sd of success: 2.1 ± 0.8 mean ± sd of failure: 2.4 ± 1.1 mean ± sd of success: 83.5 ± 11.9 mean ± sd of failure: 80.1 ± 21.1 mean ± sd of success: 65.8 ± 17.9 mean ± sd of failure: 74.8 ± 24.2 sensitivity: 8.6 specificity: 0 mean ± sd of success: 6.3 ± 6.7 mean ± sd of failure: 12.2 ± 10.8 sensitivity: 88.6 specificity: 16.7 sensitivity: 85.7 specificity: 8.3 sensitivity: 97.1 specificity: 0 sensitivity: 97.1 specificity: 0	<0.05
Goodnough-Hanneman, 1994	162	CVICU duration of ventilaiton	weight duration mechanical ventilation (h) mean blood pressure vital capacity in cc/kg FiO₂ PaO₂ pH age sex (proportion female)	mean ± sd of success: 80 ± 15 mean ± sd of failure: 76 ± 15 mean ± sd of success: 11 ± 5 mean ± sd of failure: 88 ± 9 mean ± sd of success: 93 ± 16 mean ± sd of failure: 79 ± 17 mean ± sd of success: 14.2 ± 5 mean ± sd of failure: 11 ± 4 mean ± sd of success: 0.61 ± 0.09 mean ± sd of failure: 0.72 ± 0.17 mean ± sd of success: 191 ± 87 mean ± sd of failure: 181 ± 108 mean ± sd of success: 7.41 ± 0.06 mean ± sd of failure: 7.35 ± 0.08 mean ± sd of success: 61 ± 12 mean ± sd of failure: 66 ± 9 sensitivity: 20.1 specificity: 75	<0.001 <0.001 0.001 <0.001 0.585 <0.001
Arom, 1995	645	CVICU duration of ventilation	cardiopulmonary bypass time aortic crossclamp time intra-operative bleeding core intra-operative temperature CK-MB peak chest tube drainage	mean ± sd of success: 88.6 ± 33.4 mean ± sd of failure: 96.9 ± 38.1 mean ± sd of success: 47.6 ± 20.6 mean ± sd of failure: 49.5 ± 19.7 mean ± sd of success: 503 ± 265 mean ± sd of failure: 539 ± 226 mean ± sd of success: 32.7 ± 1.7 mean ± sd of failure: 30.6 ± 2.8 mean ± sd of success: 40.46 ± 47.19 mean ± sd of failure: 57.46 ± 99.84 mean ± sd of success: 503 ± 265 mean ± sd of failure: 539 ± 226	0.01
Habib, 1996	507	CVICU duration of ventialation	body surface area creatinine preoperative blood urea nitrogen no. of vessels grafted no. of proximal anastomoses postoperative hemoglobin cardiopulmonary bypass time aortic crossclamp time intra-operative bleeding intraoperative fluid balance core intra-operative temperature	mean ± sd of success: 2.01 ± 0.21 mean ± sd of failure: 1.91 ± 0.22 mean ± sd of success: 1.06 ± 0.72 mean ± sd of failure: 1.09 ± 0.68 mean ± sd of success: 14.8 ± 5.2 mean ± sd of failure: 16.1 ± 6.9 mean ± sd of success: 3.02 ± 1.02 mean ± sd of failure: 3.22 ± 0.97 mean ± sd of success: 1.92 ± 0.9 mean ± sd of failure: 2.2 ± 0.87 mean ± sd of success: 7.42 ± 1.61 mean ± sd of failure: 7.18 ± 1.39 mean ± sd of success: 88.2 ± 30.8 mean ± sd of failure: 95.3 ± 34.9 mean ± sd of success: 51.8 ± 19.8 mean ± sd of failure: 54.3 ± 20.6 mean ± sd of success: 273 ± 157 mean ± sd of failure: 244 ± 171 mean ± sd of success: 1179 ± 1010 mean ± sd of failure: 1448 ± 1041 mean ± sd of success: 35.3 ± 1.9 mean ± sd of failure: 34.8 ± 2.2	<0.001 <0.07 <0.05 <0.04 <0.02 <0.02 <0.05 0.16 0.17 <0.005
Bando, 1997	586	CVICU duration of ventilation	body surface area prior myocardial infarction stroke (CVA) CHF/pulmonary edema current smoking smoking history coma renal insufficiency vital capacity % predicted VC FeV₁/FVC% FeV₁ FeV₁/VC % predicted FeV₁ dyspnea DLCO DLCO% cardiac index before bypass prior cardiac surgery cardiac surgery: valve only no. of vessels grafted priority operation cardiomegaly (on CXR) left ventricular ejection fraction fractional shortening left ventricular ejection fraction beta blockers cardiopulmonary bypass time aortic crossclamp time new Q-waves bleeding decreased cardiac output CK-MB peak chest tube drainage age	beta P value: 0.657 beta P value: 0.039 beta P value: 0.36 beta P value: 0.001 OR P value: 0.435 beta P value: 0.377 beta P value: 0.001 OR P value: 0.002 beta P value: 0.359 beta P value: 0.406 beta P value: 0.752 beta P value: 0.269 beta P value: 0.508 beta P value: 0.401 beta P value: 0.067 beta P value: 0.598 beta P value: 0.677 beta P value: 0.98 beta P value: 0.001 beta P value: 0.86 beta P value: 0.676 beta P value: 0.005 beta P value: 0.002 beta P value: 0.547 beta P value: 0.279 beta P value: 0.329 beta P value: 0.232 beta P value: 0.96 beta P value: 0.001 beta P value: 0.001 beta P value: 0.001 beta P value: 0.001 beta P value: 0.001 beta P value: 0.001 beta P value: 0.001 beta P value: 0.03	0.657 0.039 0.36 <0.001 0.435 0.377 <0.001 0.002 0.359 0.406 0.752 0.269 0.508 0.401 0.067 0.598 0.677 0.98 <0.001 0.86 0.676 0.005 0.002 0.547 0.279 0.329 0.232 0.96 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.03
Doering, 1997	62	CVICU duration of ventilation	cardiac surgery: other than just CABG cardiac surgery: CABG age <70 sex (proportion female)	sensitivity: 9.1 specificity: 74.5 sensitivity: 90.9 specificity: 25.5 sensitivity: 90.9 specificity: 52.9 sensitivity: 63.6 specificity: 70.6
Doering, 1998	116	CVICU duration of ventilation	vasoactive drugs	univariate beta: 0.63
London, 1998	299	CVICU duration of ventilation	body surface area FeV₁ no. of vessels grafted hematocrit platelet count ischemic time total bypass time operating room time operating room time w/o prep time temperature minimum on CPB crystalloid use in operating room colloid use in operating room total calculated fluid fentanyl dose midazolam dose maximum FiO₂ during anesthesia % bypass time that isoflurane was used temperature isoflurane discontinued time of arrival in SICU temperature on SICU arrival total urine output sex	mean ± sd of success: 1.99 ± 0.2 mean ± sd of failure: 1.98 ± 0.2 mean ± sd of success: 2.8 ± 0.7 mean ± sd of failure: 2.5 ± 0.8 mean ± sd of success: 3.3 ± 1 mean ± sd of failure: 3.2 ± 1 mean ± sd of success: 42 ± 4 mean ± sd of failure: 42 ± 6 mean ± sd of success: 147 ± 45 mean ± sd of failure: 141 ± 47 mean ± sd of success: 74 ± 22 mean ± sd of failure: 84 ± 28 mean ± sd of success: 115 ± 28 mean ± sd of failure: 134 ± 39 mean ± sd of success: 4.9 ± 1 mean ± sd of failure: 5.4 ± 1.3 mean ± sd of success: 5.8 ± 1.1 mean ± sd of failure: 6.3 ± 1.4 mean ± sd of success: 28.5 ± 2.5 mean ± sd of failure: 28 ± 2.9 mean ± sd of success: 2499 ± 800 mean ± sd of failure: 2721 ± 992 mean ± sd of success: 652 ± 497 mean ± sd of failure: 704 ± 619 mean ± sd of success: 2922 ± 1674 mean ± sd of failure: 3015 ± 1992 mean ± sd of success: 35.6 ± 12.4 mean ± sd of failure: 45.5 ± 22 mean ± sd of success: 0.07 ± 0.04 mean ± sd of failure: 0.09 ± 0.06 mean ± sd of success: 1.3 ± 0.8 mean ± sd of failure: 1.3 ± 0.7 mean ± sd of success: 48.4 ± 24.3 mean ± sd of failure: 43.6 ± 25.7 mean ± sd of success: 33.6 ± 3 mean ± sd of failure: 33.1 ± 3.2 mean ± sd of success: 383 ± 200 mean ± sd of failure: 313 ± 220 mean ± sd of success: 36.4 ± 0.7 mean ± sd of failure: 36.6 ± 0.7 mean ± sd of success: 1556 ± 626 mean ± sd of failure: 1847 ± 903 mean ± sd of success: 0 ± 0 mean ± sd of failure: 1.3 ± 0	0.72 0.002 0.89 0.18 0.35 0.01 <0.001 0.001 <0.001 0.28 0.16 0.93 0.66 0.002 0.003 0.99 0.15 0.23 0.003 0.05 0.009 0.5

Evidence Table 14. Results of individual observational studies, grouped according to weaning predictors

Observational Study Results: Important Weaning Predictors
Predictor	Outcome	Author, Year	Number of Patients	Predictive Power	Reported P Value
Duration of Mechanical Ventilation Prior to Weaning Hours <10 hours	successful discontinuation assessment successful extunation successful discontinuation assessment + extubation CVICU duration of ventilation successful discontinuation assessment	Hilberman, 1976 Engoren, 1999 Krieger, 1989 Bouachour, 1996 Goodnough-Hanneman, 1994 Dojat, 1996	124 82 269 26 162 38	mean ± sd of success: 13.4 ± 11.5 mean ± sd of failure: 23.7 ± 26.9 median (IQR) of success: 6.0 (4.7, 12.7) median (IQR) of failure: 15.5 (8.2, 19.5) mean ± sd of success: 62 ± 98 mean ± sd of failure: 147 ± 144 mean ± sd of success: 8 ± 4 mean ± sd of failure: 11 ± 7 mean ± sd of success: 11 ± 5 mean ± sd of failure: 88 ± 9 sensitivity: 70.6 specificity: 61.9	0.07 <0.05 <0.001 <0.001
Duration of Mechanical Ventilation Prior to Weaning Days	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Frutos, 1995 Del Rosario, 1997 Tahvanainen, 1983 Lee, 1994 Khan, 1996 Krieger, 1997 Afessa, 1999 Mohsenifar, 1993 Capdevila, 1995 Jubran, 1997 Farias, 1998 Vallverdu, 1998	73 49 47 52 213 49 118 29 67 31 84 217	mean ± sd of success: 6.0 ± 5.1 mean ± sd of failure: 11.4 ± 5.0 mean ± sd of success: 6.8 ± 7.3 mean ± sd of failure: 13.5 ± 21.1 mean ± se of success: 4.7 ± 0.5 mean ± se of failure: 6.0 ± 1.2 mean ± sd of success: 4.6 ± 3.9 mean ± sd of failure: 9.6 ± 6.8 mean ± se of success: 5 ± 0.4 mean ± se of failure: 5.2 ± 0.6 mean ± sd of success: 5.5 ± 6 mean ± sd of failure: 13 ± 11 mean ± sd of success: 10.7 ± 6.4 mean ± sd of failure: 11.8 ± 7.8 mean ± sd of success: 6.2 ± 8 mean ± sd of failure: 7 ± 4 mean ± sd of success: 14.71 ± 13.2 mean ± sd of failure: 12.21 ± 6.31 mean ± sd of success: 10.79 ± 3.26 mean ± sd of failure: 25.12 ± 9.49 median (IQR) of success: 8 (4, 13) median (IQR) of failure: 11.9 (8.9, 19.6) mean ± sd of success: 7 ± 7 mean ± sd of failure: 12 ± 12	<0.05 0.318 0.004 0.8 <0.05 0.357 >0.3 >0.05 <0.001
Minute Ventilation as ml/kg	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Jabour, 1991 Engoren, 1999 Farias, 1998	38 82 84	mean ± sd of success: 136 ± 39 mean ± sd of failure: 185 ± 53 mean ± sd of success: 105 ± 28 mean ± sd of failure: 91 ± 27 median (IQR) of success: 245(180, 320) meidan (IQR) of failure: 227 (143, 274)	<0.005 <0.05
Respiratory Rate	successful mechanical support successful discontinuation assessment successful extubation sucessful discontinuation assessment + extubation	Stroetz, 1995 Frutos, 1995 Saura, 1996b Tahvanainen, 1983 Hilbert, 1998 Afessa, 1999 Krieger, 1989 Ashutosh, 1992 Mohsenifar, 1993 Capdevila, 1995 Jubran, 1997 Farias, 1998 Vallverdu, 1998	31 73 30 47 40 118 269 30 29 67 31 84 217	mean ± se of success: 14.7 ± 3.4 mean ± se of failure: 19.8 ± 5 mean ± sd of success: 24.1 ± 5.3 mean ± sd of failure: 30.4 ± 5.5 mean ± se of success: 21 ± 1 mean ± se of failure: 23 ± 2 mean ± se of success: 23.6 ±1.2 mean ± se of failure: 19.6 ± 2 mean ± sd of success: 24 ± 5 mean ± sd of failure: 25 ± 5 mean ± sd of success: 27.4 ± 7.8 mean ± sd of failure: 28.5 ± 9.5 mean ± sd of success: 22 ± 6 mean ± sd of failure: 23 ± 8 mean ± sd of success: 22.53 ± 4.84 mean ± sd of failure: 33.27 ± 7.97 mean ± sd of success: 16 ± 4 mean ± sd of failure: 17 ± 6 mean ± sd of success: 24.16 ± 7.13 mean ± sd of failure: 28.33 ± 3.98 mean ± se of success: 22.7 ± 1.6 mean ± se of failure: 34.5 ± 2.6 median (IQR) of success: 40 (31,50) median (IQR) of failure: 46 (36,59) mean ± sd of success: 24 ± 6 mean ± sd of failure: 29 ± 8	<0.05 <0.01 0.135 0.525 >0.3 0.069 <0.001
Respiratory Rate <22	successful mechanical support	Rivera, 1997	40	sensitivity: 84 specificity: 76
Respiratory Rate <30	successful discontinuation assessment successful extubation	Dojat, 1996 Mergoni, 1996	38 51	sensitivity: 100 specificity: 76.2 sensitivity: 70 specificity: 66
No cutpoint reported		Gologorskii, 1997	127	sensitivity: 70 specificity: 72
Respiratory Rate <35	successful discontinuation assessment + extubation	Gandia, 1992	30	sensitivity: 75 specificity: 82
Respiratory Rate <38	successful discontinuation assessment + extubation	Yang, 1991 Mohsenifar, 1993	100 29	sensitivity: 92 specificity: 36 sensitivity: 100 specificity: 27
Tidal Volume	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Saura, 1996a Tahvanainen, 1983 Kline, 1987 Yang, 1993 Krieger, 1997 Engoren, 1999 Krieger, 1989 Ashutosh, 1992 Mohsenifar, 1993 Capdevila, 1995 Jubran, 1997 Vallverdu, 1998	30 47 50 31 49 82 269 30 29 67 31 217	mean ± se of success: 450 ± 20 mean ± se of failure: 440 ± 30 mean ± se of success: 270 ± 20 mean ± se of failure: 310 ± 30 mean ± sd of success: 0.34 ± 0.08 mean ± sd of failure: 0.4 ± 0.08 mean ± se of success: 0.497 ± 0.053 mean ± se of failure: 0.29 ± 0.028 mean ± sd of success: 0.31 ± 0.13 mean ± sd of failure: 0.22 ± 0.76 mean ± sd of success: 533 ± 173 mean ± sd of failure: 457 ± 131 mean ± sd of success: 371 ± 149 mean ± sd of failure: 355 ± 140 mean ± sd of success: 552.73 ± 213.69 mean ± sd of failure: 326.13 ± 99.43 mean ± sd of success: 626 ± 105 mean ± sd of failure: 608 ± 120 mean ± sd of success: 527 ± 161 mean ± sd of failure: 458 ± 188 mean ± se of success: 373 ± 45 mean ± se of failure: 263 ± 26 mean ± sd of success: 432 ± 143 mean ± sd of failure: 378 ± 134	0.356 <0.01 <0.05 >0.3 0.067 <0.04 <0.01

No cutpoint reported	successful extubation	Gologorskii, 1997	127	sensitivity: 73 specificity: 75
Tidal Volume >325	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Sassoon, 1993 Dojat, 1996 Yang, 1993 Yang, 1991 Mohsenifar, 1993	45 38 31 100 29	sensitivity: 94 specificity: 40 sensitivity: 52.9 specificity: 76.2 sensitivity: 100 specificity: 67 sensitivity: 97 specificity: 54 sensitivity: 100 specificity: 18
Tidal Volume >360	successful discontinuation assessment + extubation	Gandia, 1992	30	sensitivity: 75 specificity: 58
Tidal Volume as ml/kg	successful discontinuation assessment successful extubation	Frutos, 1995 Ochiai, 1993 Engoren, 1999	73 38 82	mean ± sd of success: 6.8 ± 1.8 mean ± sd of failure: 6.6 ± 1.9 mean ± sd of success: 9.67 ± 2.94 mean ± sd of failure: 10.08 ± 1.97 mean ± sd of success: 6.4 ± 1.9 mean ± sd of failure: 5.8 ± 1.3	0.7
Tidal Volume >4 ml/kg	successful discontinuation assessment + extubation successful extubation	Yang, 1991 Farias, 1998 Khan, 1996	100 84 213	sensitivity: 94 specificity: 39 sensitivity: 94 specificity: 43 sensitivity: 83.6 sensitivity: 28.1
Tidal Volume >6 ml/kg	successful extubation	Khan, 1996	213	sensitivity: 48.5 specificity: 71.9
Tidal Volume >6.5 ml/kg	successful discontinuation assessment + extubation	Farias, 1998	84	median (IQR) of success: 6.8 (4.8, 8)
Vital Capacity	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation CVICU duration of ventilation	Hilberman, 1976 Tahvanainen, 1983 Capdevila, 1995 Vallverdu, 1998 Peters, 1979	124 47 67 217 49	mean ± sd of success: 1.30 ± 0.63 mean ± sd of failure: 0.79 ± 0.30 mean ± sd of success: 0.80 ± 0.05 mean ± sd of failure: 0.76 ± 0.09 mean ± sd of success: 1.21 ± 0.68 mean ± sd of failure: 0.8 ± 0.35 mean ± sd of success: 1.63 ± 0.64 mean ± sd of failure: 1.30 ± 0.51 mean ± sd of success: 3.2 ± 1.1 mean ± sd of failure: 2.4 ± 0.9	<0.01 0.71 0.027 <0.001 <0.01
Vital Capacity as ml/kg	successful discontinuation assessment successful extubation CVICU duration of ventilation	Hilberman, 1976 Tahvanainen, 1983 Engoren, 1999 Goodnough-Hanneman, 1994	124 47 82 162	mean ± sd of success: 18.3 ± 7.2 mean ± sd of failure: 11.9 ± 4.0 mean difference P value: mean ± sd of success: 15.6 ± 6.2 mean ± sd of failure: 11.5 ± 3.9 mean ± sd of success: 14.2 ± 5 mean ± sd of failure: 11 ± 4	<0.01 0.253 <0.05 0.001 <0.05
Tidal Volume >6 ml/kg	successful extubation	Khan, 1996	213	sensitivity: 48.5 specificity: 71.9
Tidal Volume >6.5 ml/kg	successful discontinuation assessment + extubation	Farias, 1998	84	median (IQR) of success: 6.8 (4.8, 8)
Vital Capacity	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation CVICU duration of ventilation	Hilberman, 1976 Tahvanainen, 1983 Capdevila, 1995 Vallverdu, 1998 Peters, 1979	124 47 67 217 49	mean ± sd of success: 1.30 ± 0.63 mean ± sd of failure: 0.79 ± 0.30 mean ± sd of success: 0.80 ± 0.05 mean ± sd of failure: 0.76 ± 0.09 mean ± sd of success: 1.21 ± 0.68 mean ± sd of failure: 0.8 ± 0.35 mean ± sd of success: 1.63 ± 0.64 mean ± sd of failure: 1.30 ± 0.51 mean ± sd of success: 3.2 ± 1.1 mean ± sd of failure: 2.4 ± 0.9	<0.01 0.71 0.027 <0.001 <0.01
Vital Capacity as ml/kg	successful discontinuation assessment successful extubation CVICU duration of ventilation	Hilberman, 1976 Tahvanainen, 1983 Engoren, 1999 Goodnough-Hanneman, 1994	124 47 82 162	mean ± sd of success: 18.3 ± 7.2 mean ± sd of failure: 11.9 ± 4.0 mean difference P value: mean ± sd of success: 15.6 ± 6.2 mean ± sd of failure: 11.5 ± 3.9 mean ± sd of success: 14.2 ± 5 mean ± sd of failure: 11 ± 4	<0.01 0.253 <0.05 0.001 <0.05
Vital Capacity % predicted preoperatively	successful discontinuation assessment CVICU duration of ventilation	Hilberman, 1976 Ingersoll, 1991	124 47	mean ± sd of success: 90.7 ± 13.7 mean ± sd of failure: 71.3 ± 21.9 mean ± sd of success: 59.6 ± 15.3 mean ± sd of failure: 71.9 ± 13.9	<0.01 <0.05
Rapid Shallow Breathing Index	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Del Rosario, 1997 Yang, 1993 Hilbert, 1998 Afessa, 1999 Gandia, 1992 Capdevila, 1995 Jubran, 1997 Vallverdu, 1998	49 31 40 118 30 67 31 217	mean ± se of success: 54.5 ± 4.4 mean ± sd of success: 54.5 ±4.4 mean ± sd of success: 112.7 ±27.3 mean ± sd of success: 65.26 ±7.11 mean ± sd of success: 143.3 ±15.03 mean ± sd of success: 60 ± 2 mean ± sd of failure: 66 ± 28 mean ± sd of success: 79.2 ± 41.2 mean ± sd of failure: 103.0 ± 62.3 mean ± sd of success: 71 ± 21 mean ± sd of failure: 103 ± 15 mean ± sd of success: 50 ± 23 mean ± sd of failure: 69 ± 25 mean ± se of failure: 158 ± 20 mean ± sd of success: 65 ± 30 mean ± sd of failure: 88 ± 44	<0.01 0.062 <0.001 0.018 <0.002 <0.001
No cutpoint reported	successful extubation	Gologorskii, 1997	127	sensitivity: 84 specificity: 83
RSBI <33	successful discontinuation assessment + extubation	Yang, 1991	100	sensitivity: 75 specificity: 36
RSBI <60	successful discontinuation assessment + extubation	Capdevila, 1995	67	sensitivity: 73 specificity: 75
RSBI <65	successful mechanical support	Rivera, 1997	40	sensitivity: 90 specificity: 80
RSBI <90	successful discontinuation assessment + extubation	Gandia, 1992	30	sensitivity: 83 specificity: 82
RSBI <100	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Sassoon, 1993 Chatila, 1996a Yang, 1993 Epstein, 1995 Epstein, 1996 Leitch, 1996 Jacob, 1997 Vallverdu, 1998	45 100 31 94 218 163 183 217	sensitivity: 97 specificity: 40 sensitivity: 98 specificity: 59 sensitivity: 94 specificity: 73 sensitivity: 92 specificity: 22 sensitivity: 88.6 specificity: 23.5 sensitivity: 96.3 specificity: 0 sensitivity: 97 specificity: 33 sensitivity: 90 specificity: 36
RSBI <105	successful extubation	Lee, 1994 Mergoni, 1996 Krieger, 1997	52 51 49	sensitivity: 72 specificity: 11 sensitivity: 65 specificity: 58 sensitivity: 74 specificity: 73
RSBI <130	successful extubation successful discontinuation assessment + extubation	Krieger, 1997 Yang, 1991 Mohsenifar, 1993	49 100 29	sensitivity: 92 specificity: 57 sensitivity: 97 specificity: 64 sensitivity: 100 specificity: 27
RSBI standardized to body weight	successful discontinuation assessment + extubation	Farias, 1998	84	median (IQR) of success: 6.5 (4.3, 8.7) median (IQR) of failure: 10.5 (8.2, 14.3)
RSBI in ml/kg < 4 ml/kg	successful extubation	Khan, 1996	213	sensitivity: 24.1 specificity: 76.5 beta P value: 0.34
RSBI in ml/kg < 8 ml/kg	successful extubation	Khan, 1996	213	sensitivity: 63.8 specificity: 55.9 beta P value: 0.34
RSBI in ml/kg < 11 ml/kg	successful extubation successful discontinuation assessment + extubation	Baumeister, 1997 Farias, 1998	47 84	sensitivity: 78.9 specificity: 77.9 sensitivity: 86 specificity: 48
RSBI occlusion pressure index	successful discontinuation assessment + extubation	Vallverdu, 1998	217	mean ± sd of success: 241 ± 177 mean ± sd of failure: 452 ± 363	<0.001
RSBI occlusion pressure index <450	successful discontinuation assessment	Sassoon, 1993	45	sensitivity: 97 specificity: 60
Occlusion Pressure at 0.1 sec (P_0.1)	successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Del Rosario, 1997 Hilbert, 1998 Capdevila, 1995 Vallverdu, 1998	49 40 67 217	mean ± se of success: 3.2 ± 0.2 mean ± se of failure: 5.2 ± 1.3 mean ± sd of success: 2.4 ± 0.9 mean ± sd of failure: 2.9 ± 0.7 mean ± sd of success: 3.62 ± 1.35 mean ± sd of failure: 7.38 ± 2.67 mean ± sd of success: 3.6 ± 1.5 mean ± sd of failure: 5.0 ± 2.4	0.001 <0.001
P_0.1< 3.4	successful discontinuation assessment + extubation	Gandia, 1992	30	sensitivity: 75 specificity: 61
P_0.1 <4.4	successful discontinuation assessment + extubation	Saito, 1991	23	sensitivity: 100 specificity: 55.6
P_0.1 <4.5	successful mechanical support successful discontinuation assessment + extubation	Rivera, 1997 Vallverdu, 1998	40 217	sensitivity: 100 specificity: 100 sensitivity: 75 specificity: 55
P_0.1 <5.0	successful discontinuation assessment + extubation	Capdevila, 1995	67	sensitivity: 87 specificity: 91
P_0.1 <5.5	successful discontinuation assessment	Sassoon, 1993	45	sensitivity: 97 specificity: 40
P_0.1/MIP	successful discontinuation assessment + extubation	Capdevila, 1995 Vallverdu, 1998	67 217	mean ± sd of success: 0.05 ± 0.01 mean ± sd of failure: 0.14 ± 0.04 mean ± sd of success: 0.063± 0.032 mean ± sd of failure: 0.103± 0.056	0.001 <0.001
P_0.1/MIP <0.09	successful discontinuation assessment + extubation	Capdevila, 1995	67	sensitivity: 98 specificity: 100
P_0.1/MIP <0.14	successful extubation successful discontinuation assessment + extubation	Mergoni, 1996 Gandia, 1992	51 30	sensitivity: 85 specificity: 36 sensitivity: 1 specificity: 82
Maximum Exspiratory Pressure	successful discontinuation assessment + extubation CVICU duration of ventilation	Vallverdu, 1998 Peters, 1979	217 49	mean ± sd of success: 53 ± 25 mean ± sd of failure: 37± 17 mean ± sd of success: 68 ± 24 mean ± sd of failure: 47 ± 26	<0.001 <0.04
Pressure Time Product	successful discontinuation assessment + extubation	Jubran, 1997	31	mean ± se of success: 158 ± 23 mean ± se of failure: 255 ± 59	0.17
Pressure Time Product <275	successful mechanical support	Rivera, 1997	40	sensitivity: 100 specificity: 80
Peak Inspiratory Pressure	successful extubation	Krieger, 1997	49	mean ± sd of success: 25 ±8 mean ± sd of failure: 29±7.5
Peak Inspiratory Pressure <25	successful extubation	Khan, 1996	213	sensitivity: 44.3 specificity: 82.4 beta P value: 0.001
Peak Inspiratory Pressure <30	successful extubation	Khan, 1996		sensitivity: 77 specificity: 47.1 beta P value: 0.001
Intrinsic PEEP	successful mechanical support successful discontinuation assessment successful extubation successful discontinuation assessment + extubation	Rivera, 1997 Del Rosario, 1997 Krieger, 1997 Afessa, 1999 Jubran, 1997	40 49 49 118 31	mean ± sd of success: 1.6 ± 0.8 mean ± sd of failure: 5.8 ± 2.4 mean ± se of success: 2 ± 0.4 mean ± se of failure: 2 ± 0.5 mean ± sd of success: 0.53 ± 1.3 mean ± sd of failure: 1.5 ± 2.8 mean ± sd of success: 1.0± 2.3 mean ± sd of failure: 1.5 ± 2.5 mean ± se of success: 0.7 ± 0.1 mean ± se of failure: 2 ± 0.5	<0.001 0.395 <0.03
FiO₂	successful extubation successful discontinuation assessment + extubation CVICU duration of ventilation	Krieger, 1997 Engoren, 1999 Mohsenifar, 1993 Goodnough-Hanneman, 1994	49 82 29 162	mean ± sd of success: 0.4 ± 0.06 mean ± sd of failure: 0.38 ± 0.06 mean ± sd of success: 0.53 ± 0.08 mean ± sd of failure: 0.61 ± 0.19 mean ± sd of success: 35 ± 8 mean ± sd of failure: 40 ± 7 mean ± sd of success: 0.61 ± 0.09 mean ± sd of failure: 0.72 ± 0.17	<0.05 >0.3 <0.001
Gastric Intramucosal pH	successful discontinuation assessment + extubation	Mohsenifar, 1993	29	mean ± sd of success: 7.45 ± 0.13 mean ± sd of failure: 7.36 ± 0.2	0.07
Gastric Intramucosal pH >7.3	successful discontinuation assessment + extubation	Bouachour, 1996	26	sensitivity: 100 specificity: 100
Gastric Intramucosal pH Change	successful discontinuation assessment + extubation	Mohsenifar, 1993	29	mean of success: 0.01 mean of failure: 0.27
Gastric Intramucosal PCO₂	successful discontinuation assessment + extubation	Mohsenifar, 1993	29	mean ± sd of success: 37 ± 12 mean ± sd of failure: 49 ± 23	0.07
Gastric Intramucosal PCO₂ <60	successful discontinuation assessment + extubation	Bouachour, 1996	26	sensitivity: 95 specificity: 100
Gastric Intramucosal PCO₂ Change	successful discontinuation assessment + extubation	Mohsenifar, 1993	29	mean of success: 1 mean of failure: 62	<0.01
Cuff Leak Test	successful extubation	Fisher, 1992	72	sensitivity: 88.7 specificity: 100
Patient-Ventilator Asynchrony	successful discontinuation assessment	Chao, 1997	174	sensitivity: 96.7 specificity: 19.3
Daily Screening Test	successful extubation	Ely, 1996	300	sensitivity: 88 specificity: 67
Successful 2-hour T-piece Trial	successful discontinuation assessment	Dojat, 1996	38	sensitivity: 100 specificity: 76
Cardiac Index Before Bypass	successful discontinuation assessment	Hilberman, 1976	124	mean ± sd of success: 2.6 ± 0.8 mean ± sd of failure: 2.1 ± 0.6
Total Bypass Time	successful extubation	Rady, 1999	11330	mean ± sd of success: 108 ±46 mean ± sd of failure: 136 ± 75	<0.0001
Total Operating Room Time	successful extubation	Rady, 1999	11330	mean ± sd of success: 5.2 ± 1.5 mean ± sd of failure: 6.5 ± 3.1	<0.0001
Weaning Predictors Specific to CVICU Surgery type:CABG vs other	CVICU duration of ventilation	Peters, 1979 Doering, 1997	49 62	sensitivity: 71.4 specificity: 71.4 sensitivity: 90.9 specificity: 25.5
Total OR time	CVICU duration of ventilation	London, 1998	299	mean ± sd of success: 4.9 ± 1 mean ± sd of failure: 5.4 ± 1.3	0.001
Fentanyl dose	CVICU duration of ventilation	London, 1998	299	mean ± sd of success: 35.6 ± 12.4 mean ± sd of failure: 45.5 ± 22	0.002
Midazolam dose	CVICU duration of ventilation	London, 1998	299	mean ± sd of success: 0.07 ± 0.04 mean ± sd of failure: 0.09 ± 0.06	0.003
Mean Arterial Blood pressure	CVICU duration of ventilation	Goodnough-Hanneman, 1994	162	mean ± sd of success: 93 ± 16 mean ± sd of failure: 79 ± 17	<0.001
Age	CVICU duration of ventilation	Goodnough-Hanneman, 1994	162	mean ± sd of success: 61 ± 12 mean ± sd of failure: 66 ± 9
Study Derived Predictive Index	CVICU duration of ventilaiton	Kanter, 1986	140	sensitivity: 57 specificity: 94.7
Table N2: Observational Study Results: Important Weaning Predictors Determined by Regression Analysis Only
Observational Study Results: Important Weaning Predictors Determined by Regression Analysis Only
Predictor	Outcome	Author, Year	Number of Patients	Beta P Value
Prior Myocardial Infarction	CVICU duration of ventilation	Bando, 1997	586	0.039
CHF/Pulmonary Edema	CVICU duration of ventilation	Bando, 1997	586	<0.001
Coma	CVICU duration of ventilation	Bando, 1997	586	<0.001
Vital Capacity	CVICU duration of ventilation	Bando, 1997	586	0.359
% Predicted VC	CVICU duration of ventilation	Bando, 1997	586	0.406
% Predicted FeV₁	CVICU duration of ventilation	Bando, 1997	586	0.401
Second Surgical Procedure	CVICU duration of ventilation	Kanter, 1986	140	<0.005
Prior Cardiac Surgery	CVICU duration of ventilation	Bando, 1997	586	<0.001
Priority Operation	CVICU duration of ventilation	Bando, 1997	586	0.005
Cardiomegaly (on CXR)	CVICU duration of ventilation	Bando, 1997	586	0.002
Preoperative Mechanical Ventilation	CVICU duration of ventilation	Kanter, 1986	140	<0.05
Failed Extubation	CVICU duration of ventilation	Kanter, 1986	140	<0.005
New Q-Waves	CVICU duration of ventilation	Bando, 1997	586	<0.001
Decreased Cardiac Output	CVICU duration of ventilation	Bando, 1997	586	<0.001
Age	CVICU duration of ventilation	Kanter, 1986	140	<0.005
Tidal Volume	successful extubation	Khan, 1996	213	0.01
FiO₂	successful extubation	Khan, 1996	213	0.018
Oxygenation Index	successful extubation	Khan, 1996	213	0.012
Observation Study Results: Important Weaning Predictors Studied in 50 Patients or Fewer
Predictor	Outcome	Author, Year	Number of Patients	Predictive Power	Reported P Value
VE/V_t	successful discontinuation assessment	Jabour, 1991	38	mean ± sd of success: 25 ± 11 mean ± sd of failure: 42 ± 16	<0.001
Tidal Volume Expressed in ml/kg	successful discontinuation assessment	Jabour, 1991	38	mean ± sd of success: 5.9 ± 1.7 mean ± sd of failure: 4.8 ± 1.7	<0.05
RSBI <100 AND NIP/PI_max<0.03	successful extubation	Yang, 1993	31	sensitivity: 81 specificity: 93
Maximum Expiratory Pressure	CVICU duration of ventilation	Peters, 1979	49	mean ± sd of success: 68 ± 24 mean ± sd of failure: 47 ± 26	<0.04
PI_max	successful discontinuation assessment	Jabour, 1991	38	mean ± sd of success: 49 ± 11 mean ± sd of failure: 35 ± 15	<0.005
Pbreath/NIP	successful discontinuation assessment	Jabour, 1991	38	mean ± sd of success: 0.31 ± 0.1 mean ± sd of failure: 0.39 ± 0.14	<0.05
Change in P_t/NIF <0.4	successful extubation	Kline, 1987	50	sensitivity: 93.1 specificity: 100
Pressure Time Index	successful discontinuation assessment	Jabour, 1991	38	mean ± sd of success: 0.12 ± 0.03 mean ± sd of failure: 0.17 ± 0.07	<0.02
Inspiratory Effort Quotient <0.19	successful discontinuation assessment + extubation	Gandia, 1992	30	sensitivity: 100 specificity: 82
Effective Inspiratory Impedance	successful extubation	Hilbert, 1998	40	mean ± sd of success: 5.2 ± 1.2 mean ± sd of failure: 6.1 ± 1.3
CROP Index in ml/kg <0.1	successful extubation	Baumeister, 1997	47	sensitivity: 100 specificity: 100
MMEF 50-75	CVICU duration of ventilation	Peters, 1979	49	mean ± sd of success: 1.8 ± 1 mean ± sd of failure: 1.1 ± 0.6	<0.01
MMEF 75-85	CVICU duration of ventilation	Peters, 1979	49	mean ± sd of success: 0.9 ± 0.5 mean ± sd of failure: 0.5 ± 0.2	<0.003
Expiratory Time	successful discontinuation assessment + extubation	Jubran, 1997	31	mean ± se of success: 1.68 ± 0.16 mean ± se of failure: 1.29 ± 0.18
Change in Intrapleural Pressure	successful extubation	Kline, 1987	50	mean ± sd of success: 11.2 ± 2.9 mean ± sd of failure: 15.2 ± 4.5
Change in Intrapleural Pressure/NIF	successful extubation	Kline, 1987	50	mean ± sd of success: 0.32 ± 0.07 mean ± sd of failure: 0.53 ± 0.1
Effective Inspiratory Impedance <10	successful discontinuation assessment	Sassoon, 1993	45	sensitivity: 89 specificity: 40
Leak Test in Neonates	successful extubation	Adderley, 1987	28	sensitivity: 75 specificity: 62.5
Statistical Prediction Model	successful discontinuation assessment + extubation	Ashutosh, 1992	30	sensitivity: 93.3 specificity: 93.3
Neural Network Analysis	successful discontinuation assessment + extubation	Ashutosh, 1992	30	sensitivity: 100 specificity: 93.3
Knowledge-Based System	successful discontinuation assessment	Dojat, 1996	38	sensitivity: 100 specificity: 90.5
Weaning Index (PTI x VE/V_t)	successful discontinuation assessment	Jabour, 1991	38	sensitivity: 95 specificity: 96
Right Atrial Pressure	successful discontinuation assessment	Delooz, 1976	41	mean ± sd of success: 5.2 ± 4.2 mean ± sd of failure: 11 ± 6.2
Pre-Operative Length of Stay (days)	CVICU duration of ventilation	Ingersoll, 1991	47	mean ± sd of success: 6.3 ± 6.7 mean ± sd of failure: 12.2 ± 10.8
Age	successful discontinuation assessment	Del Rosario, 1997	49	mean ± sd of success: 63.1 ± 10 mean ± sd of failure: 72 ± 7	<0.05

Evidence Table 15. Pooled results of observational studies of weaning predictors

Predicting Successful Stepwise Reductions in Mechanical Support
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
Respiratory Rate continuous data	Stroetz (38 breaths/ min) Rivera (38 breaths/min)	1.14 (0.87, 1.50) 1.08 (0.90, 1.29)	1.10 (0.95, 1.28)	0.32 (0.06,1.71)	3.57 (0.57,22.47)	0.97 (0.92, 1.02)	0.13 (0.04, 0.22)
Predicting Successful Discontinuation Assessment
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
Minute Ventilation binary data continuous data	Sassoon (12 L/min) Chatila (10 L/min) Del Rosario (12 L/min)	0.81 (0.40, 1.64) 1.18 ( 0.90,1.52) 1.12 (0.49, 2.55)	1.13 (0.88,1.43) 1.12 (0.49, 2.55)	0.88 (0.48,1.61) 0.93 (0.56,1.55)	1.27 (0.49, 3.27) 1.21 (0.32, 4.57)	0.60 (0.22, 0.98) 0.42 (0.28, 0.55)	0.41 (0.24, 0.57) 0.63 (0.50, 0.76)
Respiratory Rate binary data continuous data	Dojat (30 breaths/min) Sassoon (38 breaths/min) Del Rosario (38 breaths/min) Jabour (38 breaths/min) Frutos (38 breaths/min) Jabour (38 breaths/min)	3.89 (1.88, 8.05) 1.41 (0.93, 2.12) 1.63 (1.01, 2.62) 1.08 (0.87, 1.35) 1.12 (0.90, 1.40) 1.05 (0.86, 1.27)	2.23 (0.83, 6.03) 1.11 (0.98, 1.24)	0.09 (0.02,0.40) 0.23 (0.08,0.63)	25.89 (2.94,228.18) 5.37 (1.72,16.79)	0.97 (0.93, 1.00) 0.97 (0.95, 1.00)	0.53 (0.11, 0.96) 018 (0.06, 0.30)
Tidal Volume binary data continuous data	Dojat (325 ml) Sassoon (325 ml) Del Rosario (325 ml) Saura (325 ml)	2.11 (0.91, 4.92) 1.57 (0.96, 2.60) 1.27 (0.85, 1.89) 1.02 (0.75, 1.37)	1.70 (1.10, 2.61) 1.10 (0.87, 1.40)	0.38 (0.11,1.34) 0.49 (0.17,1.37)	4.87 (1.68,14.11) 2.33 (0.63, 8.58)	0.74 (0.34, 1.13) 0.88 (0.81, 0.95)	0.58 (0.25, 0.91) 0.22 (0.04, 0.40)
Rapid Shallow Breathing Index binary data	Dojat (100 breaths/min/L) Sassoon (100 breaths/min/L) Chatila (100 breaths/min/L)	1.22 ( 0.93,1.61) 1.62 (0.99, 2.66) 2.39 (1.63, 3.52)	1.66 (1.08, 2.55)	0.11 (0.03,0.37)	15.86 (3.09,81.53)	0.97 (0.94, 0.99)	0.42 (0.21, 0.63)
Negative Inspiratory Force binary data continuous data	Dojat (25cm H₂0) Chatila (30cm H₂0) Frutos (25cm H₂0) Hilberman (25cm H₂0)	1.22 (0.93, 1.41) 2.19 (1.31, 3.67) 1.21 (0.75, 1.97) 1.57 (1.04, 2.36)	1.57 (0.89, 2.77) 1.41 (1.03, 1.92)	0.47 (0.32,0.70) 0.53 (0.35,0.81)	4.39 (2.00, 9.67) 2.71 (1.31, 5.61)	0.79 (0.54, 1.04) 0.74 (0.68, 0.80)	0.48 (0.04, 0.91) 0.46 (0.31, 0.60)
PI_max binary data continuous data	Sassoon (20 cm H₂O) Del Rosario (20 cm H₂O) Jabour (20 cm H₂O)	1.32 (0.87, 2.01) 1.09 (0.79, 1.49) 1.18 (0.97, 1.42)	1.15 (0.98, 1.35)	0.50 (0.15,1.66)	2.41 (0.58,10.00)	0.92 (0.81, 1.04)	0.19 (0.11, 0.27)
Predicting Successful Extubation
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
Minute Ventilation binary data continuous data	Gologorskii (not specified) Mergoni (10 L/min) Yang (15 L/min) Leitch (10 L/min) Kreiger (12 L/min) Tahvanainen (12 L/min) Engoren (12 L/min) Afessa (12 L/min)	1.91 (1.23, 2.98) 1.25 (0.82, 1.91) 1.02 (0.71, 1.45) 1.33 (0.37, 4.77) 1.02 (0.89, 1.16) 1.00 (0.85, 1.17) 1.04 (0.94, 1.16) 0.90 (0.70, 1.15)	1.31 (0.96, 1.79) 1.01 (0.94, 1.09)	0.63 (0.48,0.83) 1.16 (0.70,1.90)	2.30 (1.35, 3.93) 0.85 (0.43, 1.69)	0.63 (0.51, 0.74) 0.89 (0.78, 1.00)	0.52 (0.36, 0.67) 0.11 (0.02, 0.20)
Respiratory Rate binary data continuous data	Gologorskii (not specified) Mergoni (30 breaths/min) DeHaven (30 breaths/ min) Yang (38 breaths/min) Kreiger (38 breaths/min) Kline (38 breaths/min) Ochiai (38 breaths/min) Tahvanainen (38 breaths/min) Hibert (38 breaths/min) Engoren (38 breaths/min)	2.54 (1.52, 4.24) 2.01 (1.25, 3.25) 1.00 (0.87, 1.15) 1.61 (0.97, 2.65) 1.04 (0.89, 1.21) 1.01 (0.93, 1.09) 1.00 (0.91, 1.10) 1.01 (0.87, 1.19) 1.02 (0.91, 1.15) 1.08 (0.94, 1.24)	1.64 (1.00, 2.68) 1.02 (0.97, 1.07)	0.52 (0.34,0.79) 0.58 (0.26,1.32)	3.23 (1.24, 8.39) 1.82 (0.73, 4.51)	0.77 (0.69, 0.85) 0.97 (0.95, 0.99)	0.51 (0.17, 0.84) 0.06 (0.02, 0.10)
Tidal Volume binary data continuous data	Gologorskii (not specified) Yang (325 ml) Kreiger (325 ml) Kline (325 ml) Tahvanainen (325 ml) Engoren (325 ml)	2.92 (1.70, 5.01) 2.82 (1.43, 5.58) 3.83 (0.80,18.39) 0.71 (0.49, 1.02) 0.75 (0.33, 1.73) 1.05 (0.88, 1.25)	2.88 (1.89, 4.40) 0.93 (0.64, 1.35)	0.20 (0.03,1.26) 0.98 (0.56,1.73)	13.37(2.38,75.13) 1.44 (0.47, 4.40)	0.85 (0.62, 1.09) 0.56 (0.29, 0.84)	0.73(0.66, 0.80) 0.45 (0.08, 0.82)
Rapid Shallow Breathing Index binary data continuous data	Gologorskii (not specified) Lee (100 breaths/min/L) Mergoni (105breaths/min/L) Leitch (105 breaths/min/L) Epstein (100 breaths/min/L) Epstien (100 breaths/min/L) Yang (100breaths/min/L) Krieger (100breaths/min/L) Hilbert (100 breaths/min/L) Afessa (100 breaths/min/L)	4.67 (2.42, 8.99) 0.84 (0.61, 1.16) 1.52 (0.99, 2.36) 1.10 (0.76, 1.59) 1.17 (0.96, 1.42) 1.20 (0.93, 1.56) 3.24 (1.46, 7.19) 2.51 (1.02, 6.18) 1.14 (0.92, 1.42) 1.43 (1.05, 1.96)	1.49 (1.11, 1.99) 1.24 (1.00, 1.54)	0.39 (0.25,0.62) 0.58 (0.37,0.90)	4.44 (1.85,10.64) 2.57 (1.24, 5.32)	0.84 (0.77, 0.90) 0.84 (0.55, 1.12)	0.44 (0.24, 0.65) 0.33 (0.04,0.70)
Rapid Shallow Breathing Index Standardized to Weight binary data	Khan (8) Baumeister (11)	1.44 (0.98, 2.12) 3.13 (1.06, 9.27)	1.79 (0.98, 1.40)	0.46 (0.21,1.01)	4.11 (0.90,18.69)	0.70 (0.56, 0.84)	0.65 (0.46, 0.84)
Negative Inspiratory Force continuous data	Yang (25 cm H₂O) Engoren (25 cm H₂O)	0.23 (0.01, 4.06) 1.09 (0.97, 1.22)	1.00 ( 0.51,1.98)	0.78 (0.22,2.67)	1.14 (0.06,20.55)	0.50 (0.42,1.42)	0.48 (-0.26,1.22)
PI_max binary data continuous data	Yang (15 cm H₂O) Leitch (20 cm H₂O) Mergoni (30 cm H₂O) Kreiger (20 cm H₂O) Kline (20 cm H₂O) Tahvanainen (20 cm H₂O) Afessa (20 cm H₂O)	1.15 (0.92, 1.44) 1.29 (0.58, 2.87) 1.20 (0.87, 1.66) 1.10 (0.89, 1.37) 1.08 (0.89, 1.30) 0.98 (0.83, 1.16) 1.03 (0.94, 1.13)	1.17 (0.98, 1.40) 1.03 (0.96, 1.11)	0.60 (0.33,1.11) 0.56 (0.22,1.42)	4.53 (1.42,14.39) 1.85 (0.68, 5.05)	0.90 (0.79, 1.01) 0.95 (0.92, 0.98)	0.27 (0.14, 0.40) 0.08 (0.05, 0.12)
P_0.1/MIP binary data	el-Khatib(0.30) Yang(0.30)	2.70 (0.57,12.83) 2.14 (1.03, 4.46)	2.23 (1.15, 4.34)	0.63 (0.36,1.10)	4.53 (1.42,14.39)	0.53 (0.14, 0.92)	0.78 (0.56, 0.99)
CROP Index	Baumeister Khan	19.74 (1.32,294.3) 1.05 (0.74, 1.49)	3.31 (0.20,54.80)	0.14 (0.00,8.87)	30.6 (0.03,34057)	0.77 (0.35, 1.19)	0.71 (0.24, 1.18)
Predicting Successful Discontinuation Assessment + Extubation
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
Minute Ventilation binary data continuous data	Sahn (10 L/min) Yang (15 L/min) Gandia (12.5 L/min) Jacob (10 L/min) Jubran (12 L/min) Capdevila (12 L/min) Vallverdu (12 L/min) Kreiger (12 L/min) Ashutosh (12 L/min)	1.82 (1.17,2.82) 0.95 (0.74,1.22) 2.37 (0.93,6.05) 1.28 (0.85,1.94) 1.31 (0.92,1.85) 0.95 (0.49,1.85) 0.72 (0.59,0.89) 1.04 (0.90,1.20) 0.79 (0.46,1.36)	1.36 (0.93,1.98) 0.94 (0.75,1.19)	0.45 (0.20,1.01) 1.18 (0.74,1.86)	3.43 (0.93,12.60) 0.83 (0.39, 1.75)	0.79 (0.65, 0.93) 0.67 (0.46, 0.89)	0.44 (0.26, 0.63) 0.30 (0.16, 0.43)
Respiratory Rate binary data continuous data	Ashutosh (38 breaths/min) Yang (38 breaths/min) Mohsenifar (38 breaths/min) Gandia (35 breaths/min) Jubran (38 breaths/min) Capdevila (38 breaths/min) Vallverdu (38 breaths/min) Kreiger (38 breaths/min)	1.63 (1.08,2.47) 1.42 (1.06,1.90) 1.37 (0.95,1.99) 3.01 (1.21,7.50) 1.55 (1.06,2.25) 1.01 (0.89,1.15) 1.14 (1.05,1.24) 1.04 (0.96,1.13)	1.50 (1.23,1.38) 1.09 (1.00,1.19)	0.23 (0.12,0.44) 0.14 (0.05,0.42)	8.82 (3.54,21.98) 8.14 (2.66,24.92)	0.93 (0.87, 0.99) 0.99 (0.98, 1.00)	0.45 (0.25, 0.65) 0.11 (0.04, 0.18)
Tidal Volume binary data continuous data	Ashutosh (325 ml) Yang (325 ml) Mohsenifar (325 ml) Gandia (408ml) Jubran (325 ml) Capdevila (325 ml) Vallverdu (325 ml) Kreiger (325 ml)	1.67 (0.93,2.98) 2.06 (1.39,3.06) 1.23 (0.91,1.66) 1.75 (0.90,3.43) 2.06 (0.90,4.70) 1.20 (0.86,1.68) 1.18 (0.99,1.41) 1.07 (0.77,1.47)	1.58 (1.20,2.08) 1.18 (1.03,1.36)	0.29 (0.14,0.63) 0.70 (0.53,0.93)	6.76 (2.67,17.11) 1.74 (1.13, 2.68)	0.89 (0.80, 0.98) 0.73 (0.60, 0.86)	0.46 (0.29, 0.63) 0.42 (0.30, 0.54)
Rapid Shallow Breathing Index binary data continuous data	Gandia (105 breaths/min/L) Jacob (100 breaths/min/L) Vallverdu (100breaths/min/L) Yang (105 breaths/min/L) Mohsenifar (105breaths/min/L) Capdevila (60breaths/min/L) Jubran (100breaths/min/L)	1.52 (0.94,2.47) 1.47 (1.03,2.10) 1.41 (1.20,1.66) 2.65 (1.63,4.32) 1.37 (0.95,1.99) 2.69 (1.08,6.67) 2.79 (1.19,6.55)	1.58 (1.30,1.90) 2.79 (1.19,6.55)	0.22 (0.13,0.37) 0.39 (0.17,0.89)	8.45(4.59, 15.54) 7.25 (1.55,33.83)	0.92 (0.87, 0.97) 0.71 (0.56, 0.87)	0.47 (0.33, 0.60) 0.74 (0.60, 0.89)
Negative Inspiratory Force binary data	Jacob (not specified) Ashutosh (25 cm H₂O) Sahn (25 cm H₂O) Mohsenifar (20 cm H₂O)	1.05 (0.90,1.24) 2.45 (1.21,4.99) 35.79 (2.33,550) 1.11 (0.89,1.40)	1.32 (0.92,1.90)	0.14 (0.03,0.68)	18.69 (1.49,234.4)	0.97 (0.93, 1.00)	0.46 (-0.11,1.03)
PI_max binary data continuous data	Jubran (not specified) Gandia (not specified) Yang (15 cm H₂O) Capdevila (50 cm H₂O) Vallverdu (20 cm H₂O) Kreiger (20 cm H₂O)	1.12 (0.91,1.38) 3.01 (1.21,7.50) 1.12 (0.98,1.29) 1.38 (0.85,2.24) 1.01 (0.97,1.06) 1.13 (0.94,1.37)	1.19 (0.99, 1.43) 1.03 (0.95, 1.11)	0.34 (0.19,0.59) 0.51 (0.25,1.06)	5.33 (2.18,13.03) 2.10 (0.89, 4.96)	0.90 (0.81, 0.99) 0.94 (0.86, 1.02)	0.35 (0.09, 0.61) 0.12 (-0.06,0.29)
P_0.1/MIP binary data	Gandia (0.09) Capdevila (0.09)	10.31 (0.66,162) 25.30 (1.67,383)	16.25 (2.35,112.5)	0.15 (0.01,3.08)	114 (2.24, 5814)	0.69 (0.12, 1.25)	0.96 (0.93, 1.00)
Predicting Successful Stepwise Reduction in Mechanical Support and Discontinuation Assessment
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
Minute Ventilation continuous data	Amoateng (12 L/min) septic patients Amoateng (12 L/min) nonseptic patients	0.97 (0.54,1.75) 1.11 (0.76,1.61)	1.07 (0.78, 1.46)	0.92 (0.32,2.69)	1.16 (0.27, 5.05)	0.78 (0.59, 0.97)	0.26 (0.14, 0.37)
Rapid Shallow Breathing Index continuous data	Amoateng (100 breaths/min/L) septic patients Amoateng (100 breaths/min/L) nonseptic patients	1.88 (1.10,3.21) 1.39 (0.96,2.01)	1.53 (1.13, 2.08)	0.22 (0.04,1.15)	7.73 (1.13,52.96)	0.91 (0.84, 0.99)	0.43 (0.23, 0.62)
Negative Inspiratory Force continuous data	Amoateng (25 cm H₂O) septic patients Amoateng (25 cm H₂O) non-septic patients	1.14 (0.51,2.54) 1.42 (0.89,2.25)	1.34 (0.90, 2.00)	0.73 (0.32,1.69)	1.95 (0.49, 7.80)	0.71 (0.42, 1.01)	0.45 (0.32, 0.58)
Predicting the Duration of Ventilation in Cardiac Surgery Patients
Predictor	Author (threshold)	Study LR + (95% CI)	Summary LR + (95% CI)	Summary LR -(95% CI)	Summary OR (95% CI)	Summary Sensitivity (95% CI)	Summary Specificity (95% CI)
CABG binary data	Doering Peters	1.18 (0.90,1.54) 2.36 (1.06,5.26)	1.50 (0.79, 2.86)	0.42 (0.24,0.75)	4.25 (1.46,12.35)	0.80 (0.64, 0.96)	0.48 (0.05, 0.91)