Matching donor to recipient in lung transplantation: How much does size matter?

Abstract

The impact of size matching between donor and recipient is unclear in lung transplantation. Therefore, we determined the relation of donor lung size to 1) posttransplant survival and 2) pulmonary function as measured by forced expiratory volume in 1 second. From 1990 to 2006, 469 adults underwent lung transplantation with lungs from donors aged 7 to 70 years. Donor and recipient total lung capacities were calculated using established formulae (predicted total lung capacity), and actual recipient lung size was measured in the pulmonary function laboratory. Disparity between donor and recipient lung size was expressed as a ratio of donor predicted total lung capacity to recipient predicted total lung capacity-the predicted total lung capacity ratio-and predicted donor total lung capacity to actual recipient total lung capacity-the actual total lung capacity ratio. Survival was measured by multiphase hazard methodology and repeated measures of National Health and Nutrition Examination Survey-normalized forced expiratory volume in 1 second analyzed by temporal decomposition. Predicted total lung capacity ratio and actual total lung capacity ratio ranged widely, from 0.55 to 1.59 and 0.52 to 4.20, respectively. Overall survival was unaffected by predicted total lung capacity ratio (P = .3) or actual total lung capacity ratio (P = .5). Patients with emphysema and an actual total lung capacity ratio of 0.67 or less or 1.03 or greater had higher predicted mortality (P = .01). During the first posttransplant year, forced expiratory volume in 1 second increased and then gradually declined. Predicted total lung capacity ratio and actual total lung capacity ratio had a small impact on forced expiratory volume in 1 second, primarily in the late phase after transplant in a disease-specific manner. Size matching between donor and recipient using predicted total lung capacity ratio and actual total lung capacity ratio is an effective technique. Wide discrepancies in lung sizing do not affect overall posttransplant survival or pulmonary function. Therefore, a greater degree of lung size mismatch can likely be accepted, thereby improving patients' odds of undergoing transplantation.