WS21.3 Acute changes in the lung clearance index after physiotherapy in children with cystic fibrosis

Abstract

Objectives The lung clearance index (LCI) is becoming a prominent endpoint for assessing interventions in cystic fibrosis (CF) concurrent with daily physiotherapy. We examined the acute time-course of change in LCI following positive expiratory pressure (PEP) chest physiotherapy in children with an acute pulmonary exacerbation of CF. Methods To assess the repeatability of our LCI measurements, 71 children, aged 8–18, with stable CF performed multiple-breath nitrogen washout (MBNW) reporting LCI. For the main study, 39 children, aged 8–18, admitted for acute exacerbations of CF were recruited on day 5 of admission to perform MBNW, spirometry and body plethysmography prior to supervised PEP. MBNW was then performed immediately after PEP, and at 1, 2 and 3 hours post-intervention. All lung function tests were repeated 24 hours after baseline measurement. Results Repeatability, expressed as the coefficient of variation (CoV), of LCI was 6.1(3.2)% in subjects with stable CF and 8.7(3.4)% in those with a pulmonary exacerbation. PEP significantly increased LCI, peaking at 1 hour post-intervention (8.82 to 9.81, p Conclusion The CoV for LCI was low in stable CF but increased in those with pulmonary exacerbations. In subjects with a pulmonary exacerbation of CF, ventilation inhomogeneity (LCI) acutely increases after physiotherapy on a background of overall improvement over 24 hours. This indicates standardisation of time of LCI measurement with respect to physiotherapy is required.