Intermittent hypothermic asanguineous cerebral perfusion (cerebroplegia) protects the brain during prolonged circulatory arrest. A phosphorus 31 nuclear magnetic resonance study

A system has been developed for the nuclear magnetic resonance spectroscopic evaluation of cerebral high-energy phosphate levels during hypothermic total circulatory arrest and reperfusion by means of cardiopulmonary bypass in large animals. The use of intermittent hypothermic asanguineous cerebral perfusion, termed cerebroplegia, for the preservation of cerebral high-energy phosphates during a 2-hour period of hypothermic total circulatory arrest and reperfusion has been evaluated. Cardiopulmonary bypass was used to achieve deep hypothermia (12° to 15 °C) during 2 hours of circulatory arrest and reperfusion. Juvenile sheep were divided into two groups. Group 1 animals (n = 8) (no cerebroplegia) served as the control group. In group 2 animals (n = 7), cerebroplegia was established by intermittent bilateral carotid artery infusion of a hypothermic oxygenated asanguineous cardioplegic solution. Nuclear magnetic resonance spectroscopy recorded changes in cerebral adenosine triphosphate, creatine phosphate, and intracellular pH. Adenosine triphosphate, creatine phosphate, and pH were higher in the group 2 animals for all points during the arrest period and until 60 minutes after reperfusion (p < 0.05). Electroencephalographic activity returned after 36 minutes of reperfusion in group 2, but it did not return until 117 minutes in group 1 (p < 0.05). In summary, cerebral high-energy phosphates and pH were maintained and the electroencephalographic signal returned more rapidly during circulatory arrests with the institution of cerebroplegia. These studies suggest that cerebroplegia is protective of the brain during circulatory arrest.