title: Acute respiratory distress syndrome: performance of ventilator at simulated altitude.
abstract: BACKGROUND
  Ventilation of Acute Respiratory Distress Syndrome (ARDS) is a challenge, and there is definitely a need for lack of variations between delivered and set tidal volume (Vt). We have assessed the ability of the ventilator T-birdVS02 and LTV-1000 to deliver to a lung model with ARDS a set Vt at different simulated altitudes.
  
  
  METHODS
  We used a decompression chamber to mimic the hypobaric environment at a range of simulated cabin altitudes of 1,500, 2,500, and 3,000 m (4,000, 6,670, and 8,000 feet, respectively). Ventilators were tested with realistic parameters. Vt was set at 400 mL and 250 mL in an ARDS lung model. Comparisons of preset to actual measured values were accomplished using a t test for each altitude.
  
  
  RESULTS
  The T-birdVS02 showed a decrease in the volume delivered. Comparisons of actual delivered Vt and set Vt demonstrated a significant difference starting at 1,500 m for a Vt set of 400 mL and at 2,500 m for Vt set of 250 mL. At these altitudes, the variations between Vt set and delivered were more than 10%. With decreasing barometric pressure, the LTV-1000 showed mostly an increase in volume delivered. Comparisons of actual delivered Vt and set Vt demonstrated a significant difference at 2,500 m for a Vt set of 400 mL and at 3,000 m for Vt set of 250 mL. The delivered Vt remained within 10% of the set Vt.
  
  
  CONCLUSIONS
  Clinicians involved in aerial evacuations must keep in mind the performance and limitations of their ventilator system.
authors.affiliation: Department of Anesthesia and Intensive Care, Military Hospital Val-de-Grace, Paris, France. jeanpierre.tourtier@free.fr
authors.forename: Jean P
authors.initials: JP
authors.lastname: Tourtier
authors.forename: Thomas
authors.initials: T
authors.lastname: Leclerc
authors.forename: Audrey
authors.initials: A
authors.lastname: Cirodde
authors.forename: Nicolas
authors.initials: N
authors.lastname: Libert
authors.forename: Michel
authors.initials: M
authors.lastname: Man
authors.forename: Marc
authors.initials: M
authors.lastname: Borne
mesh_terms: D000337:Aerospace Medicine; D000531:Altitude; D006801:Humans; D008953:Models, Anatomic; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D012122:Ventilators, Mechanical