Grant: CIHR Fellowship

Patients undergoing medical assistance in dying (MAiD) can qualify as organ donors. In patients undergoing MAiD, death is declared via circulatory criteria (DCC), and is defined as the permanent loss of brain function following the absence of cerebral blood flow. Death is officially documented when arterial pulse pressure becomes <5 mmHg (systolic - diastolic). A 5-minute observation period is then undertaken to ensure permanent cessation of brain circulation, after which organ donation commences. Prolongation of when MAiD commences to when death is declared (a period referred to as warm ischemic time) is associated with decreased function of donated organs. Additionally, if warm ischemic time exceeds certain thresholds, then the organ grafts are discarded due to conerns of non-viability. However, these threshold values are based on studies of critically ill patients in the intensive care unit, and have never been evaluated in the setting of MAiD. As such, it is not possible to say if these thresholds would apply to patients undergoing MAiD. Systemic blood pressure in these patients may not correlate well with cerebral blood flow. It is thus possible that cerebral blood flow may cease well before a pulse pressure of <5 mmHg is achieved. This creates the possibility where physiologic circulatory death is present (absent cerebral blood flow), but the clinical definition of death (pulse pressure <5 mmHg) is not. If the time gap between these two states could be reduced, then warm ischemic time would be reduced, and the function of donated organs would increase. Furthermore, a long warm ischemic time also results in potential donor organs being discarded. We aim to study whether the absence of cerebral blood occurs prior to achieving a pulse pressure of <5 mmHg in patients undergoing MAiD, which would result in a shorter warm ischemic time and increase both the quantity and quality of potential donor organs for transplantation.