Donor-Recipient Weight Mismatch and Primary Graft Dysfunction Risk Post-Lung Transplantation

Purpose The relevance of donor-to-recipient weight matching is unknown in lung transplantation, but has been associated with increased 30-day mortality in heart transplants. A lung graft from a lower weight donor could be exposed to a higher cardiac output than it is accustomed to, which may result in increased capillary leak and the development of primary graft dysfunction (PGD). We hypothesized that the risk of severe PGD would be higher in recipients who received lungs from a donor with a lower weight than that of the recipient. Methods We conducted a retrospective review of patients undergoing lung transplantation at our center between January 2004 and December 2016. Lobar and combined heart/lung transplant recipients were excluded. The risk factor of interest was donor-to-recipient weight ratio (DRWr), and primary outcome was PGD3 [partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2 ratio) ≤ 200mmHg at 48 or 72 hours post-transplant with bilateral infiltrates on imaging]. We used multivariable logistic regression to test the association between DRWr and PGD3, adjusted for DR height ratio, indication diagnosis, recipient sex, transplant type, donor age, donor smoking exposure > 20 pack years and graft total ischemic time. Results 505 patients were eligible for study, of which 485 (96%) underwent double lung transplant. 96 (19%) recipients developed PGD3. DRWr ranged from 0.38 to 3.46 with a median ratio of 1.01 (interquartile range 0.86 - 1.23). DRWr ≤ 1 was associated with an adjusted odds ratio of 2.27 [95% confidence interval 1.34, 3.96, p=0.003] of developing PGD3. There was a dose response noted (see Figure 1). Donor age (p=0.004) and graft ischemic time (p=0.048) remained significant predictors of PGD3 in the model. Conclusion Lung transplantation from a donor weighing less than the recipient is associated with a higher rate of grade 3 PGD. We hypothesize this is related to increased cardiac output relative to pulmonary vascular surface area of the graft.