Effect of size (mis)matching in clinical double-lung transplantation

Current United Network for Organ Sharing policy requires listing lung transplant recipients with an acceptable donor weight range, but lung size is a function of height, age, sex, and race. Frequently, lung transplant recipients are underweight, which results in a large discrepancy between donor and recipient weights. We reviewed our experience with size discrepancy between donors (D) and recipients (R) of 49 double-lung transplant (DLTX) procedures since July 1990. Pneumoreduction procedures were performed in 11 recipients of lungs judged to be too large at the time of DLTX (right middle lobectomy, 2; lingulectomy, 2; both, 6; right middle lobectomy and bilateral apical resections, 1). Predicted forced vital capacity (FVC) and total lung capacity (TLC) of donors and recipients were calculated. Donors were larger than recipients in general (D:R height = 1.02; D:R weight = 1.46), and, as a result, recipient-predicted lung volumes were smaller than donor-predicted lung volumes (D:R FVC = 1.1; D:R TLC = 1.1). Recipients undergoing pneumoreduction procedures had a significantly greater size discrepancy between donors and recipients; thus, both the ratio of D:R and the difference between D and R predicted FVC and TLC were significantly greater among recipients who underwent pneumoreduction, compared with nonreduced recipients. For recipients in the pneumoreduction group, predicted FVC and TLC were recalculated, with a proportionate amount subtracted based on the number of pulmonary segments removed. When the "corrected" FVC and TLC of the donors were compared with recipient-predicted FVC and TLC, there was no longer any significant difference between reduced and non-reduced groups, which implies that visual estimate of size mismatch at surgery is an accurate measure of size discrepancy. Post-DLTX spirometry showed identical improvement in FVC in patients who had pneumoreduction and those who did not, and survival at 6 months was identical in both groups. We conclude that pneumoreduction had no adverse effect on survival or post-DLTX spirometry, allowing safe use of larger donors in small recipients. Also, because lung size is more a function of height than weight, this study challenges the United Network for Organ Sharing practice of listing recipients with an acceptable donor weight range.