**3.1 Abdominal normothermic regional perfusion**

In uDCD, cannulation for the establishment of abdominal NRP is performed post-mortem after death is declared, typically in the emergency department. In cDCD, in contrast, cannulation for abdominal NRP may be performed either prior to the withdrawal of life support (pre-mortem) or following the declaration of death. Pre-mortem cannulation may be performed either percutaneously or via femoral cut-down in a variety of settings (intensive care unit, radiology suite, operating room). Post-mortem cannulation, on the other hand, is most often done in open abdomen in the operating room, though some centers have used femoral artery and vein catheters or guidewires placed prior to withdrawal of care to access and thereby cannulate the femoral vasculature following the declaration of death [12].

For uDCD donors and cDCD donors with pre-mortem cannulation, a bolus of heparin is administered, and cannulation of unilateral femoral vessels is performed either via open femoral cutdown and isolation of the femoral artery and vein or percutaneously using Seldinger technique [11]. Cannulae are left clamped and connected to the tubing of the primed NRP circuit. The contralateral femoral artery is also cannulated with an aortic occlusion balloon catheter, which is left deflated in the case of cDCD and advanced into the supraceliac aorta under radiographic control. Following the withdrawal of life support and the declaration of death in cDCD, the aortic occlusion balloon is inflated, and the abdominal NRP circuit is initiated (**Figure 2**). Proper positioning of the balloon excluding the aortic arch vessels is confirmed by chest radiograph and absence of flow measured in a left radial arterial catheter.

For cDCD donors undergoing open post-mortem cannulation, once death has been declared, the surgical team performs midline laparotomy to cannulate the abdominal aorta immediately proximal to and the infrarenal inferior vena cava immediately distal to their respective bifurcations. Cannulae are connected to the tubing of the primed NRP circuit, the supraceliac aorta is clamped, and NRP is initiated.

Blood is sampled at baseline and every 30 minutes during abdominal NRP to determine biochemical, hematological, and acid-base parameters. In general, pump flow is maintained >1.7 L/min/m2 , temperature 35–37°C, PaO2 100–150 mmHg, and hemoglobin >7 g/dL. Hepatic transaminases should remain stable throughout NRP; levels >3× the upper limit of normal at baseline and/or >4× the upper limit of normal at the end of NRP may be considered relative contraindications for recovery of the liver and pancreas [10, 11]. In general, NRP is run for a minimum of 1 hour and a maximum of 4 hours to allow adequate reconditioning of the abdominal organs and recovery of energy substrates without provoking additional end-organ injury [4, 5, 7, 8, 13, 14].
