Warm ischemic tolerance in collapsed pulmonary grafts is limited to 1 hour

Objective To determine the length of warm ischemic tolerance in pulmonary grafts from non-heart-beating donors. Summary Background Data If lungs could be retrieved for transplant after circulatory arrest, the sh ortage of donors might be significantly alleviated. Great concern, however, exists about the length of tolerable warm ischemia before cold preservatio n of pulmonary grafts retrieved from such non-heart-beating donors. Methods The authors compared the influence of an increasing postmortem interval on graft function in an isolated, room air-ventilated rabbit lung model during blood reperfusion up to 4 hours. Four groups of cadavers (four animals per group) were studied. in group 1, lungs were immediately reperfused. In the other groups, cadavers with lungs deflated were left at room temperature f or 1 hour(group 2), 2 hours (group 3), or 4 hours (group 4). Results Pulmonary vascular resistance was enhanced in all ischemic groups compared with the control group. An increase was noted with longer postmortem interv als in peak airway pressure and in weight gain. A concomitant decline was o bserved in the venoarterial oxygen pressure gradient caused by progressive edema formation, as reflected by the wet-to-dry weight ratio at the end of reperfusion. Conclusions Warm ischemia resulted in increased pulmonary vascular resistance. Graft fu nction in lungs retrieved 1 hour after death was not significantly worse th an in nonischemic lungs. Therefore, 60 minutes of warm ischemia with the lu ng collapsed may be tolerated before cold storage. Further studies are nece ssary to investigate whether lungs retrieved from non-heart-beating donors will become a realistic alternative for transplant.