title: Noninvasive proportional assist ventilation compared with noninvasive pressure support ventilation in hypercapnic acute respiratory failure.
abstract: OBJECTIVE
  To compare short-term administration of noninvasive proportional assist ventilation (NIV-PAV) and pressure support ventilation (NIV-PSV).
  
  
  METHODS
  Prospective, crossover, randomized study.
  
  
  METHODS
  Medicosurgical intensive care unit in a nonteaching hospital.
  
  
  METHODS
  Twelve chronic obstructive pulmonary disease patients admitted for hypercapnic acute respiratory failure.
  
  
  METHODS
  NIV-PSV and NIV-PAV given in a randomized order after baseline evaluation in continuous positive airway pressure. Using a flow-triggering ventilator, NIV-PAV was adjusted using the runaway method and compared with NIV-PSV at similar peak inspiratory airway pressure.
  
  
  RESULTS
  Flow, airway pressure, and changes in esophageal pressure were measured and the tidal volume, the patient's inspiratory work of breathing, and the esophageal pressure--time product were calculated. Arterial pH and PaCO(2) were measured and breathing comfort was assessed using a visual analogic scale. Peak inspiratory airway pressure (17 +/- 3 cm H(2)O) and tidal volume were similarly increased with the two modalities with no change in respiratory rate. The change in esophageal pressure was similarly decreased (from 20 +/- 8 cm H(2)O in continuous positive airway pressure to 12 +/- 7 in NIV-PSV and 10 +/- 5 cm H(2)O in NIV-PAV) as well as inspiratory muscle effort indexes. Arterial pH and PaCO(2) were similarly improved. Breathing comfort was significantly improved in NIV-PAV (+38 +/- 38%) but not in NIV-PSV (+11 +/- 23%). The tidal volume was more variable in NIV-PAV (89 +/- 18%) than in NIV-PSV (15 +/- 8%) and changes in tidal volume variability were significantly correlated (p =.02) with changes in breathing comfort.
  
  
  CONCLUSIONS
  In chronic obstructive pulmonary disease patients with hypercapnic acute respiratory failure, NIV-PAV was able to unload inspiratory muscles similarly to NIV-PSV but may be more comfortable than NIV-PSV.
authors.affiliation: Réanimation Polyvalente, Institut Mutualiste Montsouris, Paris, France. marc.wysocki@imm.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Wysocki
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Richard
authors.forename: Patrick
authors.initials: P
authors.lastname: Meshaka
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000628:therapy*; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive; D012131:Respiratory Insufficiency / Q000628:therapy*; D015656:Respiratory Mechanics; D012132:Respiratory Muscles; D018709:Statistics, Nonparametric; D014939:Work of Breathing