title: Comparison of five bilevel pressure ventilators in patients with chronic ventilatory failure: a physiologic study.
abstract: OBJECTIVE
  To compare patient-ventilator interaction and comfort in patients with chronic ventilatory failure (CVF) who are undergoing noninvasive positive-pressure ventilation with five different commercial bilevel pressure home ventilators. Also, we wanted to evaluate the short-term effects of the five ventilators on physiologic variables, namely, breathing patterns and inspiratory muscles.
  
  
  METHODS
  Randomized, controlled physiologic study.
  
  
  METHODS
  Pulmonary division of a rehabilitation institution.
  
  
  METHODS
  Twenty-eight patients with CVF due to COPD (17 patients) and restrictive chest wall diseases (11 patients).
  
  
  METHODS
  Sensation of comfort, breathing patterns and minute ventilation (E), respiratory muscles and mechanics, and patient-ventilator interaction during both unassisted and assisted ventilation with the five ventilators applied randomly.
  
  
  RESULTS
  The five ventilators showed different flow and pressure waveforms. The level of comfort was somehow different among the studied ventilators. When compared to unassisted ventilation, all ventilators induced a significant increase in E (p < 0.01) without any significant difference among ventilators. Use of the five ventilators resulted in significant differences in peak airway opening pressure (Pao,peak) but not in mean airway opening pressure computed over a period of 1 min (PTPao,min), and in a duty cycle. Ineffective efforts (IEs) were similar among the studied ventilators. In comparison with unassisted ventilation, all ventilators induced significant reductions in inspiratory muscle effort (p < 0.001). No significant relationship was found between level of comfort and PTPao,min, Pao,peak, or the number of IEs.
  
  
  CONCLUSIONS
  In stable, awake patients with CVF, all of the studied ventilators were well-tolerated, although with a great intersubject variability in comfort, and performed well in terms of improvement in E and inspiratory muscle unloading, thus fulfilling the aims of mechanical ventilation. This effect was obtained with similar levels of PTPao,min, despite the fact that Pao,peak was different among some ventilators. The number of IEs was similar among the studied ventilators.
authors.affiliation: Pulmonary Division, Scientific Institute, Fondazione Salvatore Maugeri IRCCS, I-25064 Gussago (BS), Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Vitacca
authors.forename: Luca
authors.initials: L
authors.lastname: Barbano
authors.forename: Silvestro
authors.initials: S
authors.lastname: D'Anna
authors.forename: Roberto
authors.initials: R
authors.lastname: Porta
authors.forename: Luca
authors.initials: L
authors.lastname: Bianchi
authors.forename: Nicolino
authors.initials: N
authors.lastname: Ambrosino
mesh_terms: D000368:Aged; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications; D012131:Respiratory Insufficiency / Q000628:therapy*; D013896:Thoracic Diseases / Q000150:complications; D012122:Ventilators, Mechanical