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 prearrest 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.