Influence of surface cooling and rewarming on whole-body oxygen supply-demand balance.
The influence of moderate hypothermia induced by surface cooling was studied on haemodynamic variables and whole-body oxygen consumption in a 43-yr-old female undergoing clipping of multiple cerebral aneurysms. Decreasing oesophageal temperature to 32 degrees C lowered the whole-body oxygen consumption by about 40%. The decrease in oxygen consumption was matched by a proportional decrease in cardiac output. During the rewarming phase, there was a progressive increase in oxygen consumption, which was matched by a proportional increase in cardiac output. This resulted in a constant oxygen extraction ratio, as evidenced by oxyhaemoglobin saturation which remained constant at different body temperatures. While the temperature-corrected PVO2 decreased progressively with cooling, the temperature-uncorrected PVO2 remained constant at all body temperatures. Thus the use of temperature-uncorrected PO2 during hypothermia may simplify clinical interpretation because of our familiarity with normothermic PO2 values and the normothermic oxyhaemoglobin dissociation curve.
Baraka
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Department of Anesthesiology, American University of Beirut, Lebanon.
D000328:Adult; D001831:Body Temperature / Q000502:physiology; D002536:Cerebral Arteries / Q000601:surgery*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007036:Hypothermia, Induced; D002532:Intracranial Aneurysm / Q000601:surgery*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D010313:Partial Pressure; D017694:Rewarming
D010108:Oxyhemoglobins; D010100:Oxygen