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

Abstract

Aim: Single (SLT_x) and double lung transplantation (DLT_x) are therapeutic options for end-stage interstitial lung disease (ILD). The aim of this study is to describe oscillometry indices in stable SLT_x compared to DLT_x recipients.

Methods: Oscillometry & spirometry were performed on all stable LT_x recipients at 2 Australian centres from 2020-2021 using TremoFlo C-100 to obtain resistance (R₅, R_5-19), reactance (X₅) and reactance area (A_x). Subjects with baseline, acute or chronic lung allograft dysfunction were excluded. SLT_x for ILD (SLT_x-ILD) recipients were compared with DLT_x for ILD (DLT_x-ILD) and were matched by age and gender.

Results: 17 SLT_x-ILD were included and compared with 10 matched stable DLT_x-ILD. Baseline demographics of SLT_x-ILD [88% males; mean age 64 (SD 5)] and DLT_x-ILD [90% males; mean age 63 (SD 6)] were similar. Median X₅ (-1.86 vs -1.14, p=0.02) and A_x (12.60 vs 5.57, p=0.04) differed significantly between SLT_x-ILD and DLT_x-ILD recipients, but resistance (R₅, R_5-19) measurements did not.

Conclusion: SLT_x for ILD is characterised by significantly worse X₅ and A_x (increased elastance) as compared to DLT_x for ILD. The abnormal reactance, in addition to insignificant differences in resistance measurements between SLT_x and DLT_x, 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 patients' baseline measurements – can be indicative of earlier progressive lung graft dysfunction and a worse prognosis in SLT_x, as compared to using traditional methods.