Abstract
Oxygen utilization during surface-induced deep hypothermia under ether anesthesia and respiratory alkalosis, with and without 30 minutes of circulatory arrest, was studied in 12 dogs. Oxygen consumption and saturation, hemoglobin, hematocrit, Po 2, Pco 2, and pH of arterial and mixed venous blood were measured, and oxygen content, arteriovenous oxygen differences, and cardiac output were calculated. There were slightly decreased but persistent arteriovenous oxygen differences during cooling until low cardiac output developed around 18°C., which would suggest continued unloading of oxygen from hemoglobin despite the presence of severe alkalosis. The oxygen debt developed during total circulatory occlusion or from low cardiac output was repaid in the early rewarming period when circulation was reestablished. Venous Po 2 became progressively lower below 25°C. Tissue oxygen uptake is presumably accomplished by lowering tissue oxygen tension, but this drop apparently does not grossly impair tissue function since all dogs tolerated the procedure well and are long-term survivors.
Published Version
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