title: Comparison of airway pressure release ventilation to conventional mechanical ventilation in the early management of smoke inhalation injury in swine.
abstract: OBJECTIVE
  The role of airway pressure release ventilation in the management of early smoke inhalation injury has not been studied. We compared the effects of airway pressure release ventilation and conventional mechanical ventilation on oxygenation in a porcine model of acute respiratory distress syndrome induced by wood smoke inhalation.
  
  
  METHODS
  Prospective animal study.
  
  
  METHODS
  Government laboratory animal intensive care unit.
  
  
  METHODS
  Thirty-three Yorkshire pigs.
  
  
  METHODS
  Smoke inhalation injury.
  
  
  RESULTS
  Anesthetized female Yorkshire pigs (n = 33) inhaled room-temperature pine-bark smoke. Before injury, the pigs were randomized to receive conventional mechanical ventilation (n = 15) or airway pressure release ventilation (n = 12) for 48 hrs after smoke inhalation. As acute respiratory distress syndrome developed (PaO2/Fio2 ratio <200), plateau pressures were limited to <35 cm H2O. Six uninjured pigs received conventional mechanical ventilation for 48 hrs and served as time controls. Changes in PaO2/Fio2 ratio, tidal volume, respiratory rate, mean airway pressure, plateau pressure, and hemodynamic variables were recorded. Survival was assessed using Kaplan-Meier analysis. PaO2/Fio2 ratio was lower in airway pressure release ventilation vs. conventional mechanical ventilation pigs at 12, 18, and 24 hrs (p < .05) but not at 48 hrs. Tidal volumes were lower in conventional mechanical ventilation animals between 30 and 48 hrs post injury (p < .05). Respiratory rates were lower in airway pressure release ventilation at 24, 42, and 48 hrs (p < .05). Mean airway pressures were higher in airway pressure release ventilation animals between 6 and 48 hrs (p < .05). There was no difference in plateau pressures, hemodynamic variables, or survival between conventional mechanical ventilation and airway pressure release ventilation pigs.
  
  
  CONCLUSIONS
  In this model of acute respiratory distress syndrome caused by severe smoke inhalation in swine, airway pressure release ventilation-treated animals developed acute respiratory distress syndrome faster than conventional mechanical ventilation-treated animals, showing a lower PaO2/Fio2 ratio at 12, 18, and 24 hrs after injury. At other time points, PaO2/Fio2 ratio was not different between conventional mechanical ventilation and airway pressure release ventilation.
authors.affiliation: United States Army Institute of Surgical Research, Pulmonary/Critical Care Service, Department of Medicine, Brooke Army Medical Center, Fort Sam Houston, TX, USA. andriy.batchinsky@amedd.army.mil
authors.forename: Andriy I
authors.initials: AI
authors.lastname: Batchinsky
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Burkett
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Zanders
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Chung
authors.forename: Dara D
authors.initials: DD
authors.lastname: Regn
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Jordan
authors.forename: Corina
authors.initials: C
authors.lastname: Necsoiu
authors.forename: Ruth
authors.initials: R
authors.lastname: Nguyen
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Hanson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Morris
authors.forename: Leopoldo C
authors.initials: LC
authors.lastname: Cancio
mesh_terms: D000818:Animals; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D053208:Kaplan-Meier Estimate; D012121:Respiration, Artificial / Q000379:methods; D012129:Respiratory Function Tests; D015208:Smoke Inhalation Injury / Q000503:physiopathology / Q000628:therapy*; D013552:Swine; D013997:Time Factors