COMPARISON OF THE EFFECTS OF CONTROLLED VENTILATION WITH 100-PERCENT OXYGEN, 50-PERCENT OXYGEN IN NITROGEN, AND 50-PERCENT OXYGEN IN NITROUS-OXIDE ON RESPONSES TO VENOUS AIR-EMBOLISM IN PIGS

In this randomized, experimental study in 18 pigs, we have investigate d the effects of inspiratory air in oxygen, 100% oxygen and 50% nitrou s oxide in oxygen on the detection and consequences of venous air embo lism. Each animal was tested with injections of 1.0 ml kg(-1) and 2.0 ml kg(-1) of air. All animals, except one in-the nitrous oxide group, survived the air emboli. Systolic and diastolic arterial pressures dec reased significantly in all groups after both injections of air. Pulmo nary diastolic pressures increased most in the nitrous oxide group. En d-tidal concentration of carbon dioxide decreased significantly in all groups after air injections. The difference in concentration of oxyge n in the inspiratory and expiratory gas (O-2(1 - E)) was lowest in the air group after both injections of air. On the basis of our studies w e suggest that nitrous oxide should not be used during surgery associa ted with an increased risk of venous air embolism.