Lung ultrasound to phenotype chronic lung allograft dysfunction in lung transplant recipients. A prospective observational study

Background: Bronchiolitis obliterans syndrome (BOS) and restricted allograft syndrome (RAS) are two distinct phenotypes of chronic lung allograft dysfunction (CLAD) in lung transplant (LTx) recipients.  Contrary to BOS, RAS can radiologically present with a pleuroparenchymal fibroelastosis (PPFE) pattern. This study investigates lung ultrasound (LUS) to identify potential surrogate markers of a radiological PPFE pattern in order to distinguish CLAD phenotype RAS from BOS.Methods: A prospective cohort study performed at a National Lung Transplantation Center during June 2016 to December 2017. Patients were examined with LUS and high-resolution computed tomography of the thorax (HRCT).Results: Twenty-five CLAD patients (72% males, median age of 54 years) were included corresponding to 19/6 BOS/RAS patients. LUS-identified pleural thickening was more pronounced in RAS vs. BOS patients (5.6 vs. 2.9 mm) compatible with a PPFE pattern on HRCT. LUS-identified pleural thickening as an indicator of PPFE pattern in RAS patients’ upper lobes showed a sensitivity of 100% (95%CI; 54-100%), specificity of 100% (95% CI; 82-100%), PPV of 100% (95% CI; 54-100%), and NPV of 100% (95% CI; 82-100%).Conclusion: Apical pleural thickening detected by LUS and compatible with a PPFE pattern on HRCT separates RAS from BOS in patients with CLAD. We propose LUS as a supplementary tool for initial CLAD phenotyping.FootnotesCite this article as: European Respiratory Journal 2021; 58: Suppl. 65, OA4340.This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).