Usefulness of exhaled nitric oxide to guide risk stratification for bronchiolitis obliterans syndrome after lung transplantation.

The aim of this study was to assess fractional exhaled nitric oxide (FeNO) for the early diagnosis of bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTX). 611 FeNO measurements in 166 consecutive patients were classified depending on BOS stage at the time of assessment and course during minimum follow-up of 3 months: (1) stable non-BOS, (2) unstable non-BOS, (3) stable BOS and (4) unstable BOS. Unstable course was defined as new onset of BOS≥1 or progression of BOS. FeNO before unstable course was significantly increased in comparison to their stable counterparts (non-BOS: 28.9 ± 1.2 ppb, n = 40 vs. 16.4 ± 0.8 ppb, n = 131 and BOS: 32.5 ± 1.3 ppb, n = 35 vs. 15.3 ± 0.8 ppb, n = 26; p = 0.01 each). Average time from FeNO reading to onset of deterioration was 117 ± 9 days in non-BOS and 136 ± 9 days in BOS patients. The positive and negative predictive value of FeNO >20 ppb for BOS was 69.0% and 96.9%, respectively. Serial measurements demonstrated significantly lower mean individual variation in stable recipients as compared to stable patients switching to unstable course (3.2 ± 0.3 ppb vs. 12.7 ± 1.4 ppb, p = 0.02). In particular, the excellent negative predictive value of persistently low FeNO readings for future BOS make FeNO assessments a useful tool for continuous risk stratification after LTX.

Human herpesvirus 6 in bronchalveolar lavage fluid after lung transplantation: a risk factor for bronchiolitis obliterans syndrome?

Bronchiolitis obliterans syndrome (BOS) is the limiting factor to long-term survival after lung transplantation. Previous studies suggested respiratory viral tract infections are associated with the development of BOS. To identify the impact of virus detection in bronchoalveolar lavage (BAL) fluid, we analyzed BAL samples from 87 consecutive lung transplant recipients for human herpesvirus (HHV)-6, Epstein-Barr virus, Herpes simplex virus 1/2, Cytomegalovirus, respiratory syncytical virus and adenovirus by PCR. Acute rejection, BOS and death were recorded for a mean follow-up time of 3.27 +/- 0.47 years. Results of PCR analysis and other potential risk factors were entered into a Cox regression analysis of BOS predictors and death. Only acute rejection was a distinct risk factor for BOS of all stages, death and death from BOS. HHV-6 was detected in 20 patients. Univariate and multivariate analysis revealed that HHV-6 was associated with an increased risk to develop BOS > orb = stage 1 and death, separate from the risk attributable to acute rejection. Identification of HHV-6 DNA in BAL fluid is a potential risk factor for BOS. Our results warrant further studies to elucidate a possible causal link between HHV-6 and BOS.