title: Ovine smoke/burn ARDS model: a new ventilator-controlled smoke delivery system.
abstract: BACKGROUND
  Our current ovine smoke/burn acute respiratory distress syndrome (ARDS) model utilizes a manual bee smoker. This smoke delivery system lacks standardization and reproducibility, with 20% of sheep failing to meet ARDS criteria. Time to reach ARDS criteria and survival time are also variable. The mild volutrauma (15 mL/kg) applied after smoke/burn injury may also fail to induce ARDS within 24 h. We hypothesized that these inconsistencies were associated with the bee smoker and the mild volutrauma. In the current study, we addressed these problems to improve the consistency of the smoke/burn ARDS model.
  
  
  METHODS
  Adult female sheep (n = 10) were given a 40% total body surface area third degree cutaneous burn and 48 breaths (4 × 12) of cotton smoke under general anesthesia. A modified ventilator was then used to deliver a precise and consistent smoke volume (tidal volume) to the sheep. Additional barotrauma was induced by pressure control ventilation (40 cm H(2)0). When ARDS criteria (PaO(2)/FiO(2) < 200) were met, the ARDS Network low tidal volume ventilation protocol (6-8 mL/kg ideal body weight) was used.
  
  
  RESULTS
  Carboxyhemoglobin levels were 81.4% ± 5.6% immediately following smoke injury. All sheep met ARDS criteria within 24 h (12.5 ± 4.9 h). Mean survival time post-injury was 62.1 ± 26.4 h. White blood cells and granulocytes were significantly elevated at 24 h post-smoke/burn injury. Lung tissue at necropsy was consistent with ARDS.
  
  
  CONCLUSIONS
  The refinements made to the original ovine smoke/burn ARDS model produce a more reliable time to ARDS onset, injury severity, and time of death.
authors.affiliation: Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA.
authors.forename: Cherry
authors.initials: C
authors.lastname: Ballard-Croft
authors.forename: L Ryan
authors.initials: LR
authors.lastname: Sumpter
authors.forename: Richard
authors.initials: R
authors.lastname: Broaddus
authors.forename: Joseph
authors.initials: J
authors.lastname: Alexander
authors.forename: Dongfang
authors.initials: D
authors.lastname: Wang
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Zwischenberger
mesh_terms: D000818:Animals; D001469:Barotrauma / Q000401:mortality / Q000473:pathology / Q000503:physiopathology; D056630:Beekeeping / Q000295:instrumentation; D002059:Burns, Inhalation / Q000401:mortality / Q000473:pathology / Q000503:physiopathology*; D002263:Carboxyhemoglobin / Q000378:metabolism; D004195:Disease Models, Animal; D004868:Equipment Failure; D005260:Female; D007958:Leukocyte Count; D012121:Respiration, Artificial / Q000295:instrumentation*; D012128:Respiratory Distress Syndrome / Q000401:mortality / Q000473:pathology / Q000503:physiopathology*; D012720:Severity of Illness Index; D012756:Sheep; D015208:Smoke Inhalation Injury / Q000401:mortality / Q000473:pathology / Q000503:physiopathology*
chemical_list: D002263:Carboxyhemoglobin