Assessment of Cerebral Perfusion and Activity during Normothermic Regional Perfusion in a Porcine Model of Donation after Circulatory Death

PURPOSE To determine cerebral perfusion/activity during normothermic regional perfusion (NRP) in a model of donation after circulatory death (DCD). NRP is a resuscitation strategy used for DCD hearts involving in situ reperfusion of the donor excluding cerebral circulation. Ethical concerns have been raised regarding potential return of spontaneous cerebral activity due to collateral circulation METHODS: We induced circulatory arrest by stopping mechanical ventilation in 6 donor pigs. A 15-minute stand-off period followed before resuscitation with NRP. We performed NRP via central cannulation with the supra-aortic vessels clamped and anesthetic drugs suspended. We assessed cerebral activity using Bispectral Index (BIS) and tested the presence of brainstem reflexes (pupillaryresponse, oculocephalic and corneal reflex, and spontaneous respirations). Cerebral perfusion was assessed by continuous oximetry with Near-Infrared Spectroscopy (NIRS) and a cerebral angiography RESULTS: Brainstem reflexes were uniformly absent at all time points following DCD in all cases. NIRS decreased markedly during DCD induction and became absent during NRP. A slight increase in oxygenation was noted in Case 1 during NRP; however, this stabilized at non-viable oxygenation levels. This case also demonstrated flow through collateral circulation via internal mammary arteries on angiography, but no cerebral activity was detected. BIS monitoring demonstrated absence of cerebral activity during NRP CONCLUSION: Our findings suggest that, although occasional collateral brain flow may occur, there is no significant brain perfusion or return of function during NRP. NRP is safe to be performed clinically and can enhance DCD donor organ utilization, especially in heart transplantation. Future studies are required focusing on the impact of NRP over DCD organ functional recovery and clinical outcomes.