Temperature Management During Circulatory Arrest in Cardiac Surgery

Abstract

Surgery for complex aortic pathologies such as dissections, interrupted aortic arch and aneurysms involving aortic arch, remains one of the most technically and strategically demanding intervention for cardiac surgeons. Despite the continuous development of new surgical and perfusion techniques these interventions are still associated with significant mortality and morbidity. The introduction in the Seventies of deep hypothermia made possible aortic arch surgery with a defined safe period of brain ischemia (usually 30–40 minutes) during circulatory arrest. About 20 years later the use of selective cerebral perfusion associated with deep hypothermia, made possible excellent neuroprotection for longer periods of circulatory arrest. However deep hypothermia, even if protective from ischemia, has a lot of adverse effects: increases systemic inflammatory response and organ dysfunctions, impairs ions concentration, induces arrhythmias and increases risk of severe postoperative bleeding. The possibility of selective cerebral perfusion, avoiding adverse effects of deep hypothermia and eventually reduce operation time, brought surgeons to use moderate to mild hypothermia or even normothermia. However there is no pre-clinical data supporting this practice and adverse outcomes due to inadequate temperature management (target temperature and rewarming rate) are probably underreported. Indeed, physiology and pathology of deep hypothermia are not completely understood and the ideal perfusion technique and the best temperature management are to this day still missing.