Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis.

BACKGROUND
Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Positive expiratory pressure (PEP) devices provide back pressure to the airways during expiration. This may improve clearance by building up gas behind mucus via collateral ventilation and by temporarily increasing functional residual capacity. Given the widespread use of PEP devices, there is a need to determine the evidence for their effect. This is an update of a previously published review.


OBJECTIVES
To determine the effectiveness and acceptability of PEP devices compared to other forms of physiotherapy as a means of improving mucus clearance and other outcomes in people with cystic fibrosis.


SEARCH METHODS
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. The electronic database CINAHL was also searched from 1982 to 2013.Most recent search of the Group's Cystic Fibrosis Trial Register: 02 December 2014.


SELECTION CRITERIA
Randomised controlled studies in which PEP was compared with any other form of physiotherapy in people with cystic fibrosis. This included, postural drainage and percussion, active cycle of breathing techniques, oscillating PEP devices, thoracic oscillating devices, bilevel positive airway pressure (BiPaP) and exercise. Studies also had to include one or more of the following outcomes: change in forced expiratory volume in one second; number of respiratory exacerbations; a direct measure of mucus clearance; weight of expectorated secretions; other pulmonary function parameters; a measure of exercise tolerance; ventilation scans; cost of intervention; and adherence to treatment.


DATA COLLECTION AND ANALYSIS
Three authors independently applied the inclusion and exclusion criteria to publications and assessed the risk of bias of the included studies.


MAIN RESULTS
A total of 26 studies (involving 733 participants) were included in the review. Eighteen studies involving 296 participants were cross-over in design. Data were not published in sufficient detail in most of these studies to perform any meta-analysis. These studies compared PEP to active cycle of breathing techniques (ACBT), autogenic drainage (AD), oral oscillating PEP devices, high frequency chest wall oscillation (HFCWO) and Bi level PEP devices (BiPaP) and exercise.Forced expiratory volume in one second was the review's primary outcome and the most frequently reported outcome in the studies. Single interventions or series of treatments that continued for up to three months demonstrated no significant difference in effect between PEP and other methods of airway clearance on this outcome. However, long-term studies had equivocal or conflicting results regarding the effect on this outcome. A second primary outcome was the number of respiratory exacerbations. There was a lower exacerbation rate in participants using PEP compared to other techniques when used with a mask for at least one year. Participant preference was reported in 10 studies; and in all studies with an intervention period of at least one month, this was in favour of PEP. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high-level evidence. The only reported adverse event was in a study where infants performing either PEP or postural drainage with percussion experienced some gastro-oesophageal reflux. This was more severe in the postural drainage with percussion group. Many studies had a risk of bias as they did not report how the randomisation sequence was either generated or concealed. Most studies reported the number of dropouts and also reported on all planned outcome measures.


AUTHORS' CONCLUSIONS
Following meta-analyses of the effects of PEP versus other airway clearance techniques on lung function and patient preference, this Cochrane review demonstrated that there was a significant reduction in pulmonary exacerbations in people using PEP compared to those using HFCWO in the study where exacerbation rate was a primary outcome measure. It is important to note, however, that there may be individual preferences with respect to airway clearance techniques and that each patient needs to be considered individually for the selection of their optimal treatment regimen in the short and long term, throughout life, as circumstances including developmental stages, pulmonary symptoms and lung function change over time. This also applies as conditions vary between baseline function and pulmonary exacerbations.However, meta-analysis in this Cochrane review has shown a significant reduction in pulmonary exacerbations in people using PEP in the few studies where exacerbation rate was a primary outcome measure.