Abstract
Background: 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 dfferent doses. Methods: 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. Results: 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 499 mmHg (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 circulatoryarrest. Conclusion: It appears that thiopental has protective effects against cerebral ischemia under
profound hypothermia.
Key words
Hypothermia - Circulatory Arrest - Thiopental - Aortic arch
