Effects of treadmill exercise versus Flutter® on respiratory flow and sputum properties in adults with cystic fibrosis: a randomised, controlled, cross-over trial

Abstract

Background: Treadmill exercise and airway clearance with the Flutter® device have previously been shown to improve mucus clearance mechanisms in people with cystic fibrosis (CF) but have not been compared. It is therefore not known if treadmill exercise is an adequate form of airway clearance that could replace established airway clearance techniques, such as the Flutter®. The aim of this study was to evaluate respiratory flow, sputum properties and subjective responses of treadmill exercise and Flutter® therapy, compared to resting breathing (control).

Methods: Twenty-four adults with mild to severe CF lung disease (FEV₁ 28-86% predicted) completed a three-day randomised, controlled, cross-over study. Interventions consisted of 20 min of resting breathing (control), treadmill exercise at 60% of the participant's peak oxygen consumption and Flutter® therapy. Respiratory flow was measured during the interventions. Sputum properties (solids content and mechanical impedance) and subjective responses (ease of expectoration and sense of chest congestion) were measured before, immediately after the interventions and after 20 min of recovery.

Results: Treadmill exercise and Flutter® resulted in similar significant increases in peak expiratory flow, but only Flutter® created an expiratory airflow bias (i.e. peak expiratory flow was at least 10% higher than peak inspiratory flow). Treadmill exercise and Flutter® therapy resulted in similar significant reductions in sputum mechanical impedance, but only treadmill exercise caused a transient increase in sputum hydration. Treadmill exercise improved ease of expectoration and Flutter® therapy improved subjective sense of chest congestion.

Conclusions: A single bout of treadmill exercise and Flutter® therapy were equally effective in augmenting mucus clearance mechanisms in adults with CF. Only longer term studies, however, will determine if exercise alone is an adequate form of airway clearance therapy that could replace other airway clearance techniques.

Trial registration: Australian and New Zealand Clinical Trials Registry, Registration number # ACTRN12609000168257 , Retrospectively registered (Date submitted to registry 26/2/2009, First participant enrolled 27/2/2009, Date registered 6/4/2009).

Keywords: Airway clearance; Cystic fibrosis; Exercise; Flutter®; Oscillating PEP; Physiotherapy; Sputum.

Fig. 1

Participant flow during the trial

Fig. 2

Data collection procedures on Visits 2, 3 and 4. Participants completed visual analogue scores for subjective sense of chest congestion and ease of sputum expectoration with each sputum sample. A sputum sample was also collected five minutes after the intervention (post + 5) if spontaneously expectorated (i.e. it was not requested from participants). Respiratory flow data were collected during the 20 min treatment and coughs were counted during the 20 min treatment and rest/recovery periods

Fig. 3

Change in sputum hydration. Measured by sputum solids content, from pre to post intervention (post + 0) and pre to post recovery (post + 20). A negative change represents an improvement in sputum hydration. Results are group mean and SE for the control (white), treadmill exercise (black) and Flutter® therapy (diagonal lines) interventions

Fig. 4

Change in sputum mechanical impedance (G* vector sum of sputum viscosity and elasticity) at (a) 1 rad/s and (b) 100 rad/s. Measured pre to post intervention (post + 0) and pre to post recovery (post + 20). A negative change represents an improvement in sputum mechanical impedance. Results are group mean and SE for the control (white), treadmill exercise (black) and Flutter® therapy (diagonal lines) interventions. *p < 0.03

Fig. 5

Change in subjective (a) ease of sputum expectoration and (b) feeling of chest congestion. Measured on a 10 cm visual analogue scale, from pre to post intervention (post + 0) and pre to post recovery (post + 20). A positive change represents an improvement in ease of sputum expectoration and chest congestion. Results are group mean and SE for the control (white), treadmill exercise (black) and Flutter® therapy (diagonal lines) interventions. *p < 0.02