Outcomes after transplantation of lungs preserved for more than 12 h: a retrospective study

Background Ex-vivo lung perfusion (EVLP) can be used to extend overall lung preservation time by splitting one long cold ischaemic time into two shorter ones and interposing an additional EVLP time. We assessed the outcomes after clinical transplantation of lungs with more than 12 h of preservation time. Methods For this retrospective study, we searched the Toronto Lung Transplant Program database for patients who had received at least one lung transplant between Jan 1, 2006, and April 30, 2015, at a single hospital in Toronto, Canada. We split the identified patients into those with a total preservation time of more than 12 h and those with a total preservation time of less than 12 h to act as the control group. Total preservation time was defined as the sum of first cold ischaemic time, EVLP time, and second cold ischaemic time. We excluded patients if they had received a heart-lung transplant or were younger than 18 years. In bilateral lung transplantations, we used the longer preservation time of the two lungs for analysis. Lung preservation was done according to present standards of care and EVLP was done according to the Toronto EVLP technique. The primary outcomes were survival and International Society for Heart and Lung Transplantation Primary Graft Dysfunction (PGD) grade at 72 h post-transplantation. We compared outcomes with our control group using univariable and multivariable models. Findings We identified 906 patients who met eligibility criteria and had sufficient data for analysis (<12 h group [n=809]; mean lung preservation time 400.8 min [SD 121.8] vs >12 h group [n=97]; 875.7 min [109.0]). Median hospital and intensive-care unit length of stay were similar between the less than 12 h group and the more than 12 h group (hospital stay: 23 days [16-42] vs 25.5 days [17-50.25], p=0.60; intensive-care unit stay: 4 days [2-14] vs 4 days [2-16], p=0.53). PGD grade was also not different between the two groups at 72 h post-transplantation (p=0.85). There was also no difference in survival between the two groups as shown on Kaplan-Meier survival curves (p=0.61). Multivariable survival analysis using Cox's model showed increasing recipient age to be a significant variable affecting survival. Interpretation Extension of graft preservation time beyond 12 h with EVLP does not negatively affect early lung transplantation outcomes. Extension of clinical lung preservation times might allow for more transplantations to be done as a result of improved facilitation and increased flexibility around timing of lung transplantation operations.