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Background: Transpulmonary passage of air emboli can lead to fatal brain‐ and myocardial infarctions. We studied whether pigs with open chest and pericardium had a greater transpulmonary passage of venous air emboli than pigs with closed thorax. Methods: We allocated pigs with verified closed foramen ovale to venous air infusion with either open chest with sternotomy and opening of the pleura and pericardium (n = 8) or closed thorax (n = 16). All pigs received a five‐hour intravenous infusion of ambient air, starting at 4‐6 mL/kg/h and increased by 2 mL/kg/h each hour. We assessed transpulmonary air passage by transesophageal M‐mode echocardiography and present the results as median with inter‐quartile range (IQR). Results: Transpulmonary air passage occurred in all pigs with open chest and pericardium and in nine pigs with closed thorax (56%). Compared to pigs with closed thorax, pigs with open chest and pericardium had a shorter to air passage (10 minutes (5‐16) vs. 120 minutes (44‐212), P <.0001), a smaller volume of infused air at the time of transpulmonary passage (12 mL (10‐23) vs.170 mL (107‐494), P <.0001), shorter time to death (122 minutes (48‐185) vs 263 minutes (248‐300, P =.0005) and a smaller volume of infused air at the time of death (264 mL (53‐466) vs 727 mL (564‐968), P =.001). In pigs with open chest and, infused air and time to death correlated strongly (r = 0.95, P =.001). Conclusion: Open chest and pericardium facilitated the transpulmonary passage of intravenously infused air in pigs. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Any gas will flow down the path of least resistance and highest compliance. This is a problem in the treatment of severe unilateral lung disease in the intensive care unit (ICU). Deep sedation interferes with the diaphragm's ability to distribute air into the lower lung. Spontaneous breathing in a conscious patient, in combination with mechanical ventilation via an endotracheal tube inserted into the left main stem bronchus, can recruit collapsed alveoli. Any gas will flow down the path of least resistance and highest compliance. This is a problem in the treatment of severe unilateral lung disease in the intensive care unit (ICU). Deep sedation interferes with the diaphragm's ability to distribute air into the lower lung. Spontaneous breathing in a conscious patient, in combination with mechanical ventilation via an endotracheal tube inserted into the left main stem bronchus, can recruit collapsed alveoli. [ABSTRACT FROM AUTHOR]