Venous air embolism is a consequence of air being introduced into the venous circulation, and subsequently to the right heart, and pulmonary circulation. When small amounts of air reach pulmonary circulation they can be removed by gas diffusion across the arteriolar wall into the alveoli, amounts of gas exceeding 50 ml can cause pulmonary outflow tract obstruction with or without concomitant arterial embolisation. [from
HPO]