PT  - JOURNAL ARTICLE
AU  - Driskel, Madeleine
AU  - Horsley, Alex
AU  - Fretwell, Laurice
AU  - Clayton, Nigel
AU  - Al-Aloul, Mohamed
TI  - Lung clearance index in detection of post-transplant bronchiolitis obliterans syndrome
AID  - 10.1183/23120541.00164-2019
DP  - 2019 Oct 01
TA  - ERJ Open Research
PG  - 00164-2019
VI  - 5
IP  - 4
4099  - http://openres.ersjournals.com/content/5/4/00164-2019.short
4100  - http://openres.ersjournals.com/content/5/4/00164-2019.full
SO  - erjor2019 Oct 01; 5
AB  - Background Long-term outcomes after lung transplantation are often limited by the development of obliterative bronchiolitis (OB), which is clinically defined using spirometry as bronchiolitis obliterans syndrome (BOS). Lung clearance index (LCI), derived from multiple breath washout (MBW) testing, is a global measure of ventilation heterogeneity that has previously been shown to be a more sensitive measure of obstructive small airway diseases than spirometry. We aimed to assess the feasibility of LCI in adult lung transplant patients and to compare LCI to BOS grade.Methods 51 stable adult double-lung transplant recipients performed sulfur hexafluoride MBW in triplicate on a single occasion, using a closed-circuit Innocor device. BOS grades were derived from serial spirometry according to International Society for Heart and Lung Transplantation criteria and, where available, high-resolution computed tomography (HRCT) evidence of OB was recorded.Results LCI was successfully performed in 98% of patients. The within-visit coefficient of variation for repeat LCI measurements was 3.1%. Mean LCI increased significantly with BOS grades: no BOS (n=15), LCI 7.6; BOS-0p (n=16), LCI 8.3; BOS-1 (n=11), LCI 9.3; BOS-2–3 (n=9), LCI 13.2 (p<0.001). 27 patients had HRCT within 12 months. LCI in those with HRCT evidence of OB was higher than those without OB (11.1 versus 8.2, p=0.006). 47% patients displayed abnormal LCI (>7) despite a normal forced expiratory volume in 1 s (FEV1) (>80% of baseline).Conclusions LCI measurement in lung transplant recipients is feasible and reproducible. LCI increased with increasing BOS grade. A significant proportion of this cohort had abnormal LCI with preserved FEV1, suggesting early subclinical small airway dysfunction, and supporting a role for MBW in the early identification of BOS.BOS limits post-lung transplant outcomes. LCI and phase III slope indices, derived from MBW measured by a novel closed-circuit technique, increase with BOS severity and may allow detection of mild disease before conventional spirometric methods. http://bit.ly/2L113yC