CEREBRAL OXYGEN-METABOLISM MEASURED DURING HYPOTHERMIC CIRCULATORY ARREST - A CASE-REPORT

Infrared transmission spectroscopy was used to detect changes in cerebral oxy- and deoxyhemoglobin attenuation of infrared light in a patient undergoing circulatory arrest at 15-degrees-C. Wavelength specific attenuation was used to determine hemoglobin oxygen saturation in the cerebral vasculature using a previously described paradigm. The fate of the residual oxygenated hemoglobin in the cerebrovascular compartment was followed during 15 min of circulatory arrest at 15-degrees-C, and cerebral oxygen metabolism was identified as the progressive desaturation of this hemoglobin. The aggregate arterial and venous saturation fell from a normal value of 70% to an abnormally low value of 50%. Reperfusion resulted in near normalization of cerebrovascular oxygen saturation over 5 min, but evidence of persistent mild desaturation below pre-arrest baseline followed reperfusion. This case demonstrates both continued cerebral oxygen metabolism under hypothermic, circulatory arrest conditions and a cerebral oxygen delivery-consumption mismatch during reperfusion.