title: Effects of manual rib cage compressions on expiratory flow and mucus clearance during mechanical ventilation.
abstract: OBJECTIVE
  We investigated the effects of two different types of manual rib cage compression on expiratory flow and mucus clearance during prolonged mechanical ventilation in pigs.
  
  
  METHODS
  Prospective randomized animal study.
  
  
  METHODS
  Animal research facility, University of Barcelona, Spain.
  
  
  METHODS
  Nine healthy pigs.
  
  
  RESULTS
  Pigs were tracheally intubated, sedated, paralyzed, and mechanically ventilated. The animals were prone on a surgical bed in the anti-Trendelenburg position. The experiments were carried out at approximately 60 and 80 hrs from the beginning of mechanical ventilation. Two types of manual rib cage compressions were tested: Hard and brief rib cage compressions synchronized with early expiratory phase (hard manual rib cage compression) and soft and gradual rib cage compressions applied during the late expiratory phase (soft manual rib cage compression). The interventions were randomly applied for 15min with a 15-min interval between treatments. Respiratory flow and mucus movement were assessed during the interventions. Respiratory mechanics and hemodynamics were assessed prior to and after the interventions. Peak expiratory flow increased to 60.1±7.1L/min in comparison to 51.2±4.6L/min without treatment (p < 0.0015) and 48.7±4.3L/min with soft manual rib cage compression (p = 0.0002). Similarly, mean expiratory flow increased to 28.4±5.2L/min during hard manual rib cage compression vs. 15.9±2.2 and 16.6±2.8L/min without treatment and soft manual rib cage compression, respectively (p = 0.0006). During hard manual rib cage compression, mucus moved toward the glottis (1.01 ± 2.37mm/min); conversely, mucus moved toward the lungs during no treatment and soft manual rib cage compression, -0.28 ± 0.61 and -0.15±0.95mm/min, respectively (p = 0.0283). Soft manual rib cage compression slightly worsened static lung elastance and cardiac output (p = 0.0391).
  
  
  CONCLUSIONS
  Hard manual rib cage compression improved mucus clearance in animals positioned in the anti-Trendelenburg position. The technique appeared to be safe. Conversely, soft manual rib cage compression was not effective and potentially unsafe. These findings corroborate the predominant role of peak expiratory flow on mucus clearance.
authors: Pulmonary and Critical Care Unit, Animal Experimentation Division, Thorax Institute, Hospital Clínic, Barcelona, Spain.
authors: Joan Daniel
authors: JD
authors: Martí
authors: Gianluigi
authors: G
authors: Li Bassi
authors: Montserrat
authors: M
authors: Rigol
authors: Lina
authors: L
authors: Saucedo
authors: Otavio Tavares
authors: OT
authors: Ranzani
authors: Mariano
authors: M
authors: Esperatti
authors: Nestor
authors: N
authors: Luque
authors: Miquel
authors: M
authors: Ferrer
authors: Jordi
authors: J
authors: Vilaro
authors: Theodor
authors: T
authors: Kolobow
authors: Antoni
authors: A
authors: Torres
mesh_terms: D000818:Animals; D035641:Chest Wall Oscillation / Q000379:methods* / Q000592:standards; D005260:Female; D009079:Mucociliary Clearance / Q000502:physiology*; D017063:Outcome Assessment, Health Care; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D011446:Prospective Studies; D012123:Pulmonary Ventilation; D011897:Random Allocation; D012121:Respiration, Artificial; D013030:Spain; D013552:Swine