Cerebral Metabolism Monitoring During Hypothermia Following Resuscitation from Cardiopulmonary Arrest

Background: The aim of the present study was to evaluate cerebral metabolism monitoring during therapeutic hypothermia for global ischemic brain damage after cardiopulmonary resuscitation (CPR).

Methods: Jugular venous sampling and positron emission tomography (PET) were used. Seven comatose patients with cardiopulmonary arrest underwent hypothermia treatment as soon as possible after CPR. The body temperature of these patients was maintained at 34 degrees C for 72 h. Rewarming was performed at a rate of 1 degrees C/day. To monitor jugular venous saturation (SjO2) and lactate (lac-JV), a fiberoptic catheter was inserted into the jugular bulb. Oxygen extraction fraction (OEF) was calculated using the difference between arterial oxygen saturation (SaO2) and SjO2. 18F-fluorodeoxyglucose (FDG) PET was performed to investigate cerebral glucose metabolism at the end of therapeutic hypothermia.

Findings: The OEF was significantly increased at the end of hypothermia in four patients with favorable outcome on the Glasgow Outcome Scale (hypothermia onset 15.3 +/- 2.0% vs. hypothermia end 30.3 +/- 2.8%, P < 0.05). In three patients with unfavourable outcome (severe or worse on the Glasgow Outcome Scale), end hypothermia OEF tended to be low. There was also a reduction in FDG uptake in these three patients with unfavourable outcome. The lac-JV was significantly decreased at the end ofhypothermia treatment compared with hypothermia onset (27.7 +/- 7.4 vs. 6.0 +/- 3.0 mg/dL, P < 0.05).

Conclusions: The measurement of cerebral metabolism parameters, especially OEF, might be useful for estimation of hypothermia therapy in patients with unconsciousness after resuscitation after cardiac arrest.