Warm Ischemic Tolerance in Collapsed Pulmonary Grafts Is Limited to 1 Hour

Abstract

ObjectiveTo determine the length of warm ischemic tolerance in pulmonary grafts from non-heart-beating donors. Summary Background DataIf lungs could be retrieved for transplant after circulatory arrest, the shortage of donors might be significantly alleviated. Great concern, however, exists about the length of tolerable warm ischemia before cold preservation of pulmonary grafts retrieved from such non-heart-beating donors. MethodsThe 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 for 1 hour (group 2), 2 hours (group 3), or 4 hours (group 4). ResultsPulmonary vascular resistance was enhanced in all ischemic groups compared with the control group. An increase was noted with longer postmortem intervals in peak airway pressure and in weight gain. A concomitant decline was observed 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. ConclusionsWarm ischemia resulted in increased pulmonary vascular resistance. Graft function in lungs retrieved 1 hour after death was not significantly worse than in nonischemic lungs. Therefore, 60 minutes of warm ischemia with the lung collapsed may be tolerated before cold storage. Further studies are necessary to investigate whether lungs retrieved from nonheart-beating donors will become a realistic alternative for transplant.

In situ lung perfusion is a valuable tool to assess lungs from donation after circulatory death donors category I-II

“…The Madrid group recently updated their experience with 29 lung transplants from uncontrolled DCD donors and reported a high incidence of primary graft dysfunction (PGD) [4,5]. Our results confirm that the DCD category I-II lungs are already injured at the time of harvesting.…”

“…The group of Varella initially evaluated uncontrolled DCD donor lungs using a pulmonary flush technique [4]. Recently, lungs were assessed using EVLP before implantation [5] .…”

Monitoring of Lung Edema by Microwave Reflectometry during Lung Ischemia-Reperfusion Injury in vivo

“…Warm ischemic tolerance of the nonventilated lung is described to be up to several hours [5][6][7] . Within this period we found that 90 min of lung ischemia at 37 ° C results in signifi cant and reproducible reperfusion injury in all investigated parameters ( fi g. [3][4][5][6].…”

“…Experimental data are still lacking about the infl uence of the duration of ischemia during the early period of reperfusion in vivo on molecular expression in lung tissue and on development of pulmonary edema. Warm ischemic tolerance of nonventilated lung tissue has been shown to be between 1 and several hours [4][5][6][7] . Eppinger et al [8] established an in situ and an in vivo ischemia-reperfusion model of the left rat lung to study pathophysiological changes during 90 min of ischemia followed by reperfusion.…”

Strategies to increase limited donor resources

“…It is well known that lungs, inflated with oxygen, conserve their ability to oxygenate even after 1 h of in situ warm ischaemia following cessation of circulation [58,59]. In addition, it is recognised that topical cooling does provide some effective preservation and that this topical cooling can be conducted in situ in the nonheart-beating donor (NHBD) [60].…”