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).