Controlled brain hypothermia by extracorporeal carotid blood cooling at normothermic trunk temperatures in pigs

Cerebral hypothermia improves outcomes after brain injury. A technique is p resented for isolated brain cooling in pigs by cooling the natural blood su pply of the brain. Under general anesthesia both common carotid arteries we re exteriorized. One proximal carotid artery was connected to both distal c arotid arteries and a heat exchanger in this line controlled brain temperat ure. The second proximal carotid artery was connected to an external jugula r vein and a heat exchanger in this arteriovenous shunt was used to clamp t runk temperature. Thalamic brain temperatures of anesthetized juvenile pigs (N = 8) were clamped at 38, 25, and 30 degrees C while trunk core temperat ure was clamped at 38 degrees C. Approximately 7 min were needed to decreas e brain temperature from 38 to 25 degrees C, reducing brain electric activi ty by 76% and increasing the temperature differences between different brai n sites. Mean arterial blood pressure, heart rate, and cardiac output showe d no significant change. Re-establishment of normothermic brain temperature led to a virtually complete recovery of brain electric activity. The techn ique is suitable for investigations of ischemic and traumatic injuries. (C) 1999 Elsevier Science B.V. All rights reserved.