Addressing inadequate blood flow during normothermic regional perfusion for in-situ donation after circulatory death grafts preservation

Donation after circulatory death (DCD) has emerged as attainable strategy to tackle the issue of organ shortage, expanding the donor pool. The DCD concept has been applied to the multiple declinations of circulatory arrest, as per the Modified Maastricht Classification. Notwithstanding, whichever the scenario, DCD donors experience a variable warm ischemia time whose correlation with graft dysfunction is ascertained. This applies to both "controlled" (cDCD) donors (i.e., the timespan from the withdrawal of life-sustaining therapies to the onset of in-situ perfusion), and "uncontrolled" DCD (uDCD) (i.e., the low-flow period during cardiopulmonary resuscitation - CPR). This sums up to the no-flow time from cardiac arrest to the start of CPR for uDCD donors, and to the no-touch period for both uDCDs and cDCDs. Static and hypothermic storage may not be appropriate for DCD grafts. In order to overcome this ischemic insult, extracorporeal membrane oxygenation devices are adopted to guarantee the in-situ grafts preservation by means of techniques such as the normothermic regional perfusion (NRP) which consists in a selective abdominal perfusion obtained via the endovascular or surgical occlusion of the thoracic aorta. The maintenance of an adequate pump flood throughout NRP is therefore a sine qua non to accomplish the DCD donation. The issue of insufficient pump flow during NRP is prevalent and clinically significant but its management remains technically challenging and not standardized. Hereby we propose a systematic algorithmic approach to address this relevant occurrence.