title: Short-term effects of noisy pressure support ventilation in patients with acute hypoxemic respiratory failure.
abstract: BACKGROUND
  This study aims at comparing the very short-term effects of conventional and noisy (variable) pressure support ventilation (PSV) in mechanically ventilated patients with acute hypoxemic respiratory failure.
  
  
  METHODS
  Thirteen mechanically ventilated patients with acute hypoxemic respiratory failure were enrolled in this monocentric, randomized crossover study. Patients were mechanically ventilated with conventional and noisy PSV, for one hour each, in random sequence. Pressure support was titrated to reach tidal volumes approximately 8 mL/kg in both modes. The level of positive end-expiratory pressure and fraction of inspired oxygen were kept unchanged in both modes. The coefficient of variation of pressure support during noisy PSV was set at 30%. Gas exchange, hemodynamics, lung functional parameters, distribution of ventilation by electrical impedance tomography, breathing patterns and patient-ventilator synchrony were analyzed.
  
  
  RESULTS
  Noisy PSV was not associated with any adverse event, and was well tolerated by all patients. Gas exchange, hemodynamics, respiratory mechanics and spatial distribution of ventilation did not differ significantly between conventional and noisy PSV. Noisy PSV increased the variability of tidal volume (24.4 ± 7.8% vs. 13.7 ± 9.1%, P <0.05) and was associated with a reduced number of asynchrony events compared to conventional PSV (5 (0 to 15)/30 min vs. 10 (1 to 37)/30 min, P <0.05).
  
  
  CONCLUSIONS
  In the very short term, noisy PSV proved safe and feasible in patients with acute hypoxemic respiratory failure. Compared to conventional PSV, noisy PSV increased the variability of tidal volumes, and was associated with improved patient-ventilator synchrony, at comparable levels of gas exchange.
  
  
  BACKGROUND
  ClinicialTrials.gov, NCT00786292.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Spieth
authors.forename: Andreas
authors.initials: A
authors.lastname: Güldner
authors.forename: Robert
authors.initials: R
authors.lastname: Huhle
authors.forename: Alessandro
authors.initials: A
authors.lastname: Beda
authors.forename: Thomas
authors.initials: T
authors.lastname: Bluth
authors.forename: Dierk
authors.initials: D
authors.lastname: Schreiter
authors.forename: Max
authors.initials: M
authors.lastname: Ragaller
authors.forename: Birgit
authors.initials: B
authors.lastname: Gottschlich
authors.forename: Thomas
authors.initials: T
authors.lastname: Kiss
authors.forename: Samir
authors.initials: S
authors.lastname: Jaber
authors.forename: Paolo
authors.initials: P
authors.lastname: Pelosi
authors.forename: Thea
authors.initials: T
authors.lastname: Koch
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gama de Abreu
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D005858:Germany; D006439:Hemodynamics; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome