Early trends in Pao₂/fraction of inspired oxygen ratio predict outcome in lung transplant recipients with severe primary graft dysfunction

Background: The development of severe primary graft dysfunction (PGD) is a risk factor for perioperative death following lung transplantation. Our goal is to improve the predictive value of the earliest PaO2/fraction of inspired oxygen (P/F) measurements that gauge PGD severity. Methods: We identified 96 patients with severe PGD (P/F < 200) at ICU arrival through a retrospective review of 431 lung transplants performed at our institution from 1992 to 2005. The P/F trend, represented as quartiles of the 12-h percentage change in P/F, was analyzed using multivariate logistic regression. Study outcomes were 90-day death and long-term survival. Results: The median percentage change in P/F over 12 h was + 52% (interquartile range, +20 to 90%). We observed the highest early mortality among those in the lowest quartile of the P/F trend (an increase in P/F ≤ 20%). Ninety-day death rates decreased across the quartiles (low quartile, 32%; low-mid quartile, 9%; high-mid quartile, 5%; high quartile, 5%; test for trend, p = 0.007). After adjustment for the use of cardiopulmonary bypass, those in the lowest quartile of P/F trend had 6.8 times the odds of early death vs patients with a more favorable trend (odds ratio, 6.80; 95% confidence interval, 1.73 to 0.51; p = 0.007). In the first 5 years after transplant, there were significantly more deaths within the low quartile group vs those with a more rapidly increasing P/F trend (log-rank test, p = 0.01). Conclusions: Among lung recipients with severe PGD at ICU arrival, an improvement in P/F ≤ 20% in the first 12 h portends a poor outcome.