Protective effect of thiopental against cerebral ischemia during circulatory arrest

One of the most important disadvantages of the hypothermic circulatory arrest technique is the limited time allowable for circulatory arrest. Thiopental is usually used to protect the brain against ischemic injuries. However, it remains uncertain how well thiopental reduces cerebral metabolism. We investigated its effectiveness by comparing outcomes after different doses.

Fifty patients who underwent aortic arch repair with hypothermic circulatory arrest had their records reviewed. Electroencephalograms (EEG) and partial pressures of oxygen in the internal jugular vein (PjO2) were monitored. Following confirmation of total disappearance of EEG activity, 15 or 30 mg/kg thiopental was administered before circulatory arrest Th duration of circulatory arrest ranged from 16 to 77 min.

Hospital mortality rate was 10% and 4 (8%) patients developed neu-rologic complications, but 3 of them were transient. After thiopental infusion, PjO2 increased significantly from 430 to 499mmHg (p <0.01), indicating that thiopental reduces cerebral oxygen consumption. The rate of the decrease in PjO2 during circulatory arrest was slower with the higher thiopental dose, suggesting that thiopental lowered the cerebral metabolic rate of oxygen during circulatory arrest.

It appears that thiopental has protective effects against cerebral ischemia under profound hypothermia.