A new model of acute respiratory distress syndrome due to smoke inhalation and cutaneous burns in swine

Objective To develop a clinically relevant model of severe acute respiratory distress syndrome (ARDS) in swine with the aim to test therapeutic interventions. Methods Under intravenous anesthesia (ketamine, midazolam), female swine (44.8 ± 1.9kg) underwent tracheostomy, line placement, exposure to 30L of smoke, and a 40% total body surface area full‐thickness flame burn. Animals were monitored for 7 days with one‐on‐one ICU care. Post burn resuscitation using lactated Ringer's was guided by a computerized algorithm. At onset of ARDS [PaO 2 :FiO 2 ratio (PFR) < 200], the injury group (IG, n=5) received low‐tidal volume ventilation per ARDSNet guidelines. Time controls (TC, n=2) were uninjured. Data are means; statistics by T‐test or Wilcoxon 2‐sample test. Results Post‐injury carboxyhemoglobin level in IG was 89.8 ± 1.4% with onset of ARDS at 22 ± 1.7 hrs post‐injury. Survival time was lower in IG (65 ± 14 hrs) compared with TC (168 hrs, p<0.0001). Peak airway pressure in IG increased above 30cm H 2 O 6 hrs after injury (p<0.02). PFR in IG decreased below 200 at 24hr post‐injury (p<0.01) and remained lower than TC until the end of study. Conclusions We have created a clinically relevant porcine model of ARDS within 24 hrs of smoke and thermal injuries. Future work includes validation of various interventions for ARDS management. Source of support: U.S. Army Institute of Surgical Research