Long-term Preservation With Interim Evaluation of Lungs From a Non-Heart-Beating Donor After a Warm Ischemic Interval of 90 Minutes

Lung transplantation, like other forms of solid organ transplantation, is limited by the number of good donor organs. It is estimated that fewer than 25% of all available multiorgan donors have lungs suitable for transplantation.1 There is a growing interest in increasing the potential donor pool by turning to alternative sources such as the use of marginal donors,2 lobar or split transplants,3 living-related donors,4 or organs from circulation-arrested or so called non-heart-beating donors (NHBDs).5 Many groups6–12 have now reported data supporting the hypothesis formulated in 1991 by Egan et al (Chapel Hill, NC)5 that transplantation of lungs from NHBD might be an interesting strategy to resolve the problem of organ shortage. Also, in our laboratory we have been interested for many years in exploring the possibility of using lungs from these donors. In previous rabbit studies, we have investigated the effect of postmortem cadaver lung inflation, ventilation, and cooling13–16 on the catabolism of adenine nucleotides,17,18 on pulmonary cell viability,15 and on graft function.19 In the NHBD, the period of tolerable warm ischemia following cardiac arrest is estimated to be 1 hour.5,7,9,19 After this period, lungs should be protected against (further) tissue degradation to extend the time interval necessary to obtain family consent for organ donation and to organize organ retrieval. Different opinions exist regarding the ideal technique to protect warm ischemic lungs. Some groups13,14,20–22 are convinced that postmortem ventilation or inflation is the preferred method of protection. Others believe that topical cooling of the lungs inside the cadaver is the best technique to preserve lung viability.8,23 We have recently demonstrated that postmortem topical cooling is more effective than ventilation to protect the lung from ischemic damage after an initial 1-hour warm ischemic interval.24 In a further study, we have shown that this technique may be safely extended up to 7 hours postmortem, thereby creating a sufficient interval to organize organ retrieval (Rega F, Neyrinck A, Verleden G, et al How long can we preserve the pulmonary graft inside the non-heart-beating donor? Presented at the 39th Annual Meeting of the Society of Thoracic Surgeons, January 29–February 2, San Diego, CA). In the uncontrolled NHBDs (category I, death on arrival; and category II, failed resuscitation),25 it is impossible to evaluate the quality of the lung prior to death. To accept only those lungs with adequate function, pretransplant graft assessment is mandatory in order not to jeopardize the life of the recipient. We have developed an ex vivo evaluation model based on our own experience with isolated reperfusion of rabbit lungs19 and on the experience of Steen et al (Lund, Sweden). His group performed and described the first clinical case of successful single lung transplantation from an NHBD26 after a warm ischemic interval of 65 minutes. In this animal study, we have investigated the value of in situ preservation, including 90 minutes of warm ischemia and 150 minutes of topical cooling followed by ex vivo evaluation of lungs from NHBD prior to long-term cold storage up to 24 hours.