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

Abstract

PurposeWe sought to determine cerebral perfusion and activity during normothermic regional perfusion (NRP) in a clinically relevant porcine model of donation after circulatory death (DCD). Ethical concerns have been raised regarding the potential return of spontaneous cerebral activity due to collateral circulationMethodsWe induced hypoxic circulatory arrest by stopping mechanical ventilation in 6 donor pigs. A 15-minute warm ischemia followed before resuscitation with NRP via central cannulation with the supra-aortic vessels clamped and the anesthetic drugs suspended. We assessed cerebral activity using Bispectral Index (BIS) and single lead EEG. We also tested the presence of brainstem reflexes at baseline and during NRP. Cerebral perfusion was assessed by continuous oximetry using continuous Near-Infrared Spectroscopy (NIRS) and a cerebral angiography, performed at baseline and during NRPResultsBrainstem reflexes were uniformly absent at all time points following DCD. NIRS decreased markedly during DCD induction and became absent during NRP (fig.1A). 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 the internal mammary arteries into the vertebral vessels on angiography, but no cerebral activity was detected. Finally, BIS monitoring demonstrated absence of cerebral activity during NRP (fig.1B)ConclusionNRP provides rapid donor organ reperfusion, avoiding prolonged warm ischemic times during DCD. Our findings suggest that, although occasional collateral brain flow may occur, there is no significant brain perfusion or return of function during NRP. We believe NRP is safe to be performed clinically and can enhance DCD donor organ utilization. Future studies are required focusing on the impact of NRP over DCD organ functional recovery and clinical outcomes We sought to determine cerebral perfusion and activity during normothermic regional perfusion (NRP) in a clinically relevant porcine model of donation after circulatory death (DCD). Ethical concerns have been raised regarding the potential return of spontaneous cerebral activity due to collateral circulation We induced hypoxic circulatory arrest by stopping mechanical ventilation in 6 donor pigs. A 15-minute warm ischemia followed before resuscitation with NRP via central cannulation with the supra-aortic vessels clamped and the anesthetic drugs suspended. We assessed cerebral activity using Bispectral Index (BIS) and single lead EEG. We also tested the presence of brainstem reflexes at baseline and during NRP. Cerebral perfusion was assessed by continuous oximetry using continuous Near-Infrared Spectroscopy (NIRS) and a cerebral angiography, performed at baseline and during NRP Brainstem reflexes were uniformly absent at all time points following DCD. NIRS decreased markedly during DCD induction and became absent during NRP (fig.1A). 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 the internal mammary arteries into the vertebral vessels on angiography, but no cerebral activity was detected. Finally, BIS monitoring demonstrated absence of cerebral activity during NRP (fig.1B) NRP provides rapid donor organ reperfusion, avoiding prolonged warm ischemic times during DCD. Our findings suggest that, although occasional collateral brain flow may occur, there is no significant brain perfusion or return of function during NRP. We believe NRP is safe to be performed clinically and can enhance DCD donor organ utilization. Future studies are required focusing on the impact of NRP over DCD organ functional recovery and clinical outcomes