WS14.4 Analysis of expiratory flow rates used in autogenic drainage. Are they sufficiently high to mobilize secretions?

Abstract

Objectives: Multiple breath nitrogen washout (N 2 MBW) is increasingly used in clinical and research studies world-wide to measure ventilation distribution inhomogeneity (VI) and peripheral airway involvement in patients with Cystic Fibrosis (CF). Chest physiotherapy (CPT) is an integrated part of daily CF treatment used to clear the airways of mucus. The short-term effects of CPT on VI are unknown. The present study aimed to determine day-time variability and short-term effects of CPT on VI measured by N 2 MBW in children with CF. Methods: Prospective, controlled, intervention study of 10 randomly selected children with CF performing N 2 MBW, morning and afternoon on 3 visits one month apart. Patients performed extensive CPT supervised by a physiotherapist immediately before N 2 MBW afternoon at visit 2 and immediately before both N 2 MBW morning and N 2 MBW afternoon at visit 3, but refrained from CPT on other occasions. All patients were clinically stable at measurements. Results: Eight of 10 children with CF [mean age 10.5 years (SD = 2.9)] performed all repeated N 2 MBWs. Neither CPT nor time of day affected N 2 MBW outcome values. For the primary outcome Lung Clearance Index [mean 9.45 (SD = 1.91)], Dmorning–afternoon was 0.16, 0.10 and 0.01 (all non-significant) at visit 1, 2 and 3 respectively. Conclusion: In this study CPT showed no short-term effects on any N 2 MBW outcomes, supporting previous findings. Additionally, timing of measurement did not affect N 2 MBW and may thus be ignored. Our results are relevant when designing and interpreting future longitudinal studies. WS14.2 Tolerability of inhaled dry powder Bronchitol (mannitol)