title: Comparison of Alpha 200 and CoughAssist as intermittent positive pressure breathing devices: a bench study.
abstract: BACKGROUND
  Intermittent positive pressure breathing (IPPB) is used in non-intubated patients to increase lung volume and to enhance coughing. Alpha 200 (Salvia Lifetec, Kronberg, Germany) is a specific IPPB device. CoughAssist (Respironics France, Carquefou, France) is a mechanical  insufflator-exsufflator used to remove secretions in patients with inefficient cough. Both can also be used for intubated or tracheotomized patients. We assessed the impact of various artificial airways on the ability of the Alpha 200 and CoughAssist to generate insufflated volume.
  
  
  METHODS
  We measured the insufflated volume and pressure at the airway opening in a lung model under 2 conditions of compliance (30 or 60 mL/cm H(2)O) at single resistance of 5 cm H(2)O/L/s. The devices were used at 2 set pressures: 30 and 40 cm H(2)O. The Alpha 200 was set  at 2 inflation flows: 0.5 and 1 L/s, whereas CoughAssist was set at its highest value of 10 L/s. Measurements were done without (control) and with different size endotracheal tubes and tracheostomy cannulae. The relationships between insufflated volume and measured pressure were analyzed using  linear regressions.
  
  
  RESULTS
  The slopes and intercepts of the control relationship between insufflated volume and pressure were significantly greater with Alpha 200 at each set flow than with CoughAssist. As artificial airways were used, the insufflated volume did not differ from the control  with CoughAssist, while with Alpha 200 it increased at each flow setting and for all mechanical conditions. The largest differences in insufflated volume between the 2 devices were observed for the largest endotracheal tubes and tracheostomy cannulas and for the lowest inflation flow setting  in Alpha 200. These results can be explained in terms of how the devices function, as CoughAssist adapts by increasing flow, while Alpha 200 adapts by increasing inspiratory time.
  
  
  CONCLUSIONS
  This bench study has shown that in the presence of artificial airways the value of the insufflated  volume generated by the CoughAssist device was significantly lower than that generated by the Alpha 200 device.
authors.affiliation: Service de Réanimation Médicale et d'Assistance Respiratoire, Hôpital de la Croix Rousse, France.
authors.forename: Gaël
authors.initials: G
authors.lastname: Bourdin
authors.forename: Claude
authors.initials: C
authors.lastname: Guérin
authors.forename: Véronique
authors.initials: V
authors.lastname: Leray
authors.forename: Bertrand
authors.initials: B
authors.lastname: Delannoy
authors.forename: Sophie
authors.initials: S
authors.lastname: Debord
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bayle
authors.forename: Michèle
authors.initials: M
authors.lastname: Germain
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Richard
mesh_terms: D004867:Equipment Design; D006801:Humans; D007384:Intermittent Positive-Pressure Breathing / Q000295:instrumentation*; D007442:Intubation, Intratracheal; D008170:Lung Compliance; D013990:Tidal Volume; D014139:Tracheostomy