title: The active cycle of breathing technique: a systematic review and meta-analysis.
abstract: OBJECTIVE
  What is the best available research evidence (volume, quality, consistency, generalisability) for the active cycle of breathing technique (ACBT)?
  
  
  METHODS
  Systematic review with meta-analysis.
  
  
  METHODS
  Participants with respiratory conditions characterised by chronic sputum production.
  
  
  METHODS
  The active cycle of breathing or forced expiratory technique. COMPARATOR: All comparators including control conditions.
  
  
  METHODS
  All outcomes providing continuous data.
  
  
  RESULTS
  Twenty-four studies were included. Ten comparators were identified with the most common being conventional chest physiotherapy, positive expiratory pressure and a control. The outcomes most frequently assessed were sputum wet weight (n = 17), forced vital capacity (n = 12) and forced expiratory volume in 1 s (n = 12). Meta-analysis was completed on the primary outcome of sputum wet weight. The standardised mean difference (SMD, random effects) showed an increase in sputum wet weight during and up to 1 h post ACBT compared to conventional physiotherapy (SMD 0.32, 95%CI 0.05-0.59), external oscillatory devices (0.75, 0.48-1.02), and control (0.24, 0.02-0.46).
  
  
  CONCLUSIONS
  The overall body of evidence was classified as good (good volume, quality and consistency, excellent generalisability). High level, variable risk of bias research evidence favours ACBT over most alternatives for short-term improvements in secretion clearance.
authors.affiliation: School of Health Sciences (C7-51), University of South Australia (city east campus), GPO Box 2471, Adelaide, South Australia 5001, Australia. lucy.lewis@unisa.edu.au
authors.forename: Lucy K
authors.initials: LK
authors.lastname: Lewis
authors.forename: Marie T
authors.initials: MT
authors.lastname: Williams
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Olds
mesh_terms: D001945:Breathing Exercises; D019317:Evidence-Based Medicine; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008171:Lung Diseases / Q000378:metabolism / Q000503:physiopathology* / Q000534:rehabilitation*; D008297:Male; D015656:Respiratory Mechanics; D012138:Respiratory Therapy / Q000379:methods; D013183:Sputum / Q000378:metabolism