High Flow, High-Pressure Retrograde Cerebral Perfusion at 28°C is Safe and Effective for Hemiarch Replacement of the Ascending Aorta

Traditional retrograde cerebral perfusion (RCP) parameters may be suboptimal for washout of debris during hemiarch replacement of the ascending aorta, so we have designed a protocol of increased RCP pressure and flow at moderate hypothermia. We hypothesize that higher RCP pressure is safe in neurological outcomes in cases utilizing circulatory arrest at 28°C in elective hemiarch replacement.A retrospective review of a single-institution prospective database was used to search for all patients with elective hemiarch surgery from 2015 to 2022. Two cohorts were created-patients who received RCP only during circulatory arrest at 28°C and patients who received selective antegrade cerebral perfusion (SACP) during circulatory arrest. Neurological and postoperative outcomes were compared. Arterial blood gas measurements during RCP were taken from the left carotid of 34 patients, which were compared with the arterial blood gas from the bypass circuit to ensure adequate oxygen extraction. Propensity score matching was used to adjust for perioperative indices and patient characteristics.A total of 248 patients were in the SACP cohort and 79 patients in the RCP cohort. The two groups were similar based on patient demographics and relevant comorbidities. The cohorts differed in nadir bladder temperature, circulatory arrest time, and cardiopulmonary bypass time. After propensity matching, nadir bladder temperature, circulatory arrest, and cardiopulmonary bypass times were similar. Neurological postoperative outcomes were similar in the unmatched and matched analysis. The median pressure in the RCP group during circulatory arrest was 40 mm Hg. The median change in oxygen from bypass circuit to the carotids is 398 mm Hg with a mean oxygen extraction of 93.3%.These data demonstrate that a more aggressive approach to RCP beyond traditional constraints at 28°C is safe for short periods of circulatory arrest. Even with the new RCP parameters and after adjusting for standard patient and perioperative characteristics, there is no difference between SACP and RCP in neurological outcomes. Further, adequate oxygen extraction is achieved during RCP.