ARTERIAL GAS-BUBBLES AFTER DECOMPRESSION IN PIGS WITH PATENT FORAMEN OVALE

With patent foramen ovale (PFO), thought to be a risk factor for some forms of DCS, venous bubbles may pass through the patent opening to be come arterial bubbles. We exposed 14 anesthetized, spontaneously breat hing pigs to air at 5 bar (500 kPa, absolute pressure) for 30 min and then rapidly decompressed at 2 bar/min to 1 bar. We measured intravasc ular pressures, blood gases, and, with transesophageal echocardiology, bubbles in the pulmonary artery and ascending aorta. Autopsy showed t hat six of the pigs had a PFO. Arterial bubbles occurred more frequent ly in the PFO group (in six out of six) than in the non-PFO group (in two out of eight, P < 0.01). When arterial bubbles were detected, the venous bubble count and the pulmonary artery pressure tended to be low er in pigs with PFO than in pigs without a PFO. We conclude that a PFO increases the risk of arterial bubbles after decompression.