Baseline and chronic lung allograft dysfunction (BLAD & CLAD) are leading causes of reduced patient survival. Airway oscillometry characterises the lung's mechanical properties with greater sensitivity than spirometry. This study aims to characterise BLAD and CLAD with airway oscillometry.
Oscillometry was performed on all bilateral lung transplant (LTx) recipients at 2 Australian centres between Jan-Oct 2020 with the TremoFlo C-100 device to obtain resistance (R5, R19-5), reactance (X5), and reactance area (Ax). Patients with acute lung allograft dysfunction were excluded. CLAD was diagnosed/staged using spirometry as per ISHLT 2019 Consensus Criteria. BLAD was defined as failure to ever achieve >80%-pred FEV1 and FVC. Multivariate logistic regression measured the association between oscillometry risk of CLAD.
A total of 179 LTx recipients [47% males; median age 54 (IQR 25); duration post-LTx 5 years (IQR 7)] were recruited. 112/179 (63%) patients had no CLAD and of these 27 (24%) patients had BLAD. There was a significant difference in median X5 (-1.64 vs -1.20, p<0.01) and Ax (7.33 vs 4.71, p=0.03) between patients with BLAD compared to those without. There were no significant differences in median R5, R5-19 between patients with BLAD compared to those without. R5, R5-19, X5, Ax, were independently associated with CLAD (p<0.01) with Ax being the strongest predictor (aOR 1.14/1-unit increase, AUROC 0.82). There was a significant difference in each median oscillometry parameter in each CLAD stage, p<0.01 Figure 1
BLAD is characterised by abnormal reactance (X5 & Ax), yet resistive airway properties (R5 & R5-19) are similar to patients without BLAD. The association between oscillometry parameters and CLAD demonstrates that oscillometry provides complimentary information about lung dysfunction after transplant. Longitudinal studies are required to determine whether oscillometry has a role in earlier detection of CLAD.