title: The Mapleson C circuit clears more secretions than the Laerdal circuit during manual hyperinflation in mechanically-ventilated patients: a randomised cross-over trial.
abstract: OBJECTIVE
  What is the effect of the Mapleson C circuit compared with the Laerdal circuit in removing secretions and improving ventilation and gas exchange during manual hyperinflation?
  
  
  METHODS
  Prospective, randomised, cross-over trial.
  
  
  METHODS
  Twenty patients from a tertiary-level intensive care unit who were being mechanically ventilated.
  
  
  METHODS
  Manual hyperinflation in side-lying with both the Mapleson C or Laerdal circuit on the one day, one circuit in the morning and one in the afternoon, with a washout period of at least three hours between them.
  
  
  METHODS
  Secretion clearance was measured as sputum weight, ventilation was measured as respiratory compliance and tidal volume, while gas exchange was measured as oxygenation and CO2 removal.
  
  
  RESULTS
  The Mapleson C circuit cleared 0.89 g (95% CI 0.80 to 1.15) more secretions than the Laerdal circuit (p < 0.02). There was no difference between the Mapleson C and the Laerdal circuits on respiratory compliance (p = 0.81), tidal volume (p = 0.45), oxygenation (p = 0.28), or CO2 removal (p = 0.17).
  
  
  CONCLUSIONS
  Although more secretions were cleared using the Mapleson C compared with the Laerdal circuit in this study, this had no consequence in terms of oxygenation and compliance only trended to improve. As the study was underpowered the clinical significance of these findings is not clear.
authors.affiliation: Physiotherapy, The Alfred Hospital, Prahran, VIC, 3181, Australia. carol.hodgson@bigpond.com
authors.forename: Carol
authors.initials: C
authors.lastname: Hodgson
authors.forename: George
authors.initials: G
authors.lastname: Ntoumenopoulos
authors.forename: Heather
authors.initials: H
authors.lastname: Dawson
authors.forename: Jennifer
authors.initials: J
authors.lastname: Paratz
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D026201:Musculoskeletal Manipulations / Q000379:methods*; D011446:Prospective Studies; D001261:Pulmonary Atelectasis / Q000503:physiopathology / Q000517:prevention & control; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012121:Respiration, Artificial / Q000379:methods*; D013183:Sputum; D013990:Tidal Volume / Q000502:physiology; D016896:Treatment Outcome