The Complete Score for Comprehensive Evaluation of Donor Lungs in Ex-Vivo Lung Perfusion: An Approach for Optimizing the Outcomes of Transplantation

Abstract

<h3>Purpose</h3> The imperfection of the currently utilized tools for assessing graft function in acellular ex-vivo lung perfusion (EVLP) has led our team to develop a comprehensive evaluation scoring system. This study aimed to validate this scoring system in our clinical EVLP program. <h3>Methods</h3> One hundred twelve EVLP cases were performed in our program since 2018. Data from the first 73 cases (derivation cohort) were retrospectively analyzed to identify the included evaluation parameters and to inform the cutoff values in the scoring system using Youden index. The scoring system was then prospectively applied in the remaining 39 cases (validation cohort). The comprehensive lung evaluation EVLP (COMPLETE) score included ultrasound evaluation, lung weight measurement, compliance, airway pressure, deflation, oxygenation, lactate level, bronchoscopy, and x-ray. <h3>Results</h3> Out of 112 EVLP cases, 75 (67%) were transplanted with 98.7% 30-day survival. The incidence of primary graft dysfunction (PGD) grades 0, 1, 2, and 3 at 72 hours post-transplant were 21, 63, 8, and 8 %, respectively. The COMPLETE score cutoff value for transplant suitability identified by the derivation cohort was 12 (AUC 1, 100% sensitivity & specificity) which was then applied in the validation cohort. Only two recipients in the validation cohort had PGD3 (which appeared to be related to intraoperative factors, not donor factors). The COMPLETE score had a significant correlation with IL-1β perfusate levels (r = 0.44, <i>p</i> < .001). Nine cases did not meet the standard criteria (FDA approved) for transplant suitability on EVLP but were transplanted based on their COMPLETE scores with 100% 30-day survival. Of those, 1 had PGD0, 7 had PGD1, and 1 had PGD3. On the other hand, 10 cases met the standard criteria for transplant suitability but were deemed non-suitable based on their COMPLETE scores and the post-EVLP pathological examination showed significant edema in 4 cases, acute lung injury in 4 cases, and pulmonary embolism in 2 cases. <h3>Conclusion</h3> Our novel COMPLETE scoring system provides a protocolized comprehensive evaluation of donor lungs on EVLP. It can be used to optimize the outcomes of lung transplantation by increasing utilization rates after EVLP and by identifying donor factors that might lead to unfavorable outcomes following transplantation.