BRAIN-DAMAGE IN PROFOUND HYPOTHERMIA - PERFUSION VERSUS CIRCULATORY ARREST

Abstract

To investigate brain changes in induced deep core hypothermia (18.degree. C) with or without circulatory arrest, 4 groups of dogs were subjected to cardiopulmonary bypass (CPB) under the following conditions: differential head perfusion with pulsatile flow and simultaneous circulatory arrest to the rest of the body; differential perfusion to the head with a nonpulsatile flow; total circulatory arrest; and continuous hypothermic perfusion. Parameters analyzed were blood flow distribution; creatine kinase isoenzyme (CK-BB) elevation in the CSF and in the brain venous return; and microscopy of the brain in animals killed at 30 min, 24 and 48 h, 1 and 2 wk and 1 mo. Although minor brain tissue flow differences were found at 37.degree. C among the groups, flows equalized at 18.degree. C. A significant 7-fold brain flow increase followed the period of circulatory arrest in group III. Rise of CK-BB levels occurred in brain venous return but not in CSF in all groups. Microscopic cellular damage appeared in all groups with an equal degree of severity, regardless of the method of hypothermia and perfusion implemented.