Airway oscillometry after single lung transplantation is characterised by abnormal respiratory reactance

Aim: Single (SLTx) and double lung transplantation (DLTx) are therapeutic options for end-stage interstitial lung disease (ILD). The aim of this study is to describe oscillometry indices in stable SLTx compared to DLTx recipients. Methods: Oscillometry & spirometry were performed on all stable LTx recipients at 2 Australian centres from 2020-2021 using TremoFlo C-100 to obtain resistance (R5, R5-19), reactance (X5) and reactance area (Ax). Subjects with baseline, acute or chronic lung allograft dysfunction were excluded. SLTx for ILD (SLTx-ILD) recipients were compared with DLTx for ILD (DLTx-ILD) and were matched by age and gender. Results: 17 SLTx-ILD were included and compared with 10 matched stable DLTx-ILD. Baseline demographics of SLTx-ILD [88% males; mean age 64 (SD 5)] and DLTx-ILD [90% males; mean age 63 (SD 6)] were similar. Median X5 (-1.86 vs -1.14, p=0.02) and Ax (12.60 vs 5.57, p=0.04) differed significantly between SLTx-ILD and DLTx-ILD recipients, but resistance (R5, R5-19) measurements did not. Conclusion: SLTx for ILD is characterised by significantly worse X5 and Ax (increased elastance) as compared to DLTx for ILD. The abnormal reactance, in addition to insignificant differences in resistance measurements between SLTx and DLTx, may be due to the fibrotic contralateral native lung. However, contribution from other factors such as differences in lung size matching needs to be assessed. Longitudinal oscillometry studies are required to ascertain whether abnormal reactance – when assessed against patients9 baseline measurements – can be indicative of earlier progressive lung graft dysfunction and a worse prognosis in SLTx, as compared to using traditional methods.