Cerebral protection:
Most times due to the emergent nature of a dissection repair, neuromonitoring (EEG) is not available and systemic cooling for at least 45mins is preferred. While in elective arch surgery more tepid hypothermia levels have been advocated, in the setting of relatively unpredictable conditions intrinsic to acute dissection, we feel deeper levels of hypothermia provide increased level of safety. If the anticipated circulatory arrest time is less than 30mins, we prefer retrograde cerebral perfusion, although some surgeons continue to use use deep hypothermic circulatory arrest alone for simple “open distal anastomosis”. For longer periods of circulatory arrest or when more than a hemiarch reconstruction is needed, we utilize selective antegrade cerebral perfusion (perfusion pressure between 40-60 mmHg, flow rates between 6-10 mL/kg/min).