Usefulness of autofluorescence bronchoscopy in early diagnosis of airway complications after lung transplantation

Despite the promising results achieved so far in long-term survival after lung transplantation (LuTx), airway complications (ACs) still arise in the post-operative period. Early diagnosis and prompt treatment of ACs play a critical role in preventing their onset. Specifically, large bronchi ischemia has been recognized as a triggering factor for ACs. Autofluorescence bronchoscopy, which was first introduced for early cancer diagnosis, displays ischemic mucosae as red spots, while normal vascularized mucosae appear in green. The aim of this study is to investigate whether a significant correlation exists between ACs and the red/green (RG) ratio detected on scheduled autofluorescence bronchoscopy up to 1 year after LuTx. This prospective, observational, single-center cohort study initially considered patients who underwent LuTx between July 2014 and February 2016. All patients underwent concomitant white-light and autofluorescence bronchoscopy at baseline (immediately after LuTx), on POD7, POD14, POD21, POD28, POD45, 3 months, 6 months, and 1 year after LuTx. An autofluorescence image of the first bronchial carina distal to the anastomosis was captured and analyzed using histograms for red and green pixels; the R/G ratio was then recorded. Potential ACs were classified according according to the presence of a white-light following the MDS (macroscopic aspect, diameter and suture) criteria. The authors assessed the association between the R/G ratio and the ACs occurrence using a generalized estimating equations model. Thirty-one patients met the inclusion criteria and were therefore selected. Out of a total of 53 bronchial anastomoses, 8 developed complications (late bronchial stenosis), with an average onset time of 201 days after LuTx. ACs showed a similar baseline covariate value when compared to anastomoses that involved no complication. Generalized estimating equations regression indicated a clear association over time between the R/G ratio and the rise of complications (p = 0.023). The authors observed a significant correlation between post-anastomotic stenosis and the delayed decrease of the R/G ratio. Preliminary outcomes suggest that autofluorescence bronchoscopy may be an effective and manageable diagnostic tool, proving complementary to other instruments for early diagnosis of ACs after LuTx. Further research is needed to confirm and detail preliminary findings.