Early utilization of extracorporeal CO2 removal for treatment of acute respiratory distress syndrome due to smoke inhalation and burns in sheep

Introduction: In thermally injured patients, inhalation injury is often associated with acute respiratory distress syndrome (ARDS), and is an independent predictor of increased morbidity and mortality. Extracorporeal CO2 removal (ECCO2R) therapy offers new possibilities in protective mechanical ventilation in ARDS patients.We performed an early application of ECCO2R in mild-To-moderate ARDS in sheep ventilated in BiPAP mode. Our aim was to investigate its effect on severity of the lung injury. Material and Methods: Non-pregnant farm-bred ewes (n=15) were anesthetized and injured by a combination of wood-bark smoke inhalation and a 40% total body surface area full-Thickness burn, and were observed for 72 h or death. The animals were randomized to a Hemolung group (n=7) or a Control group (n=8) at time of ARDS onset. ECCO2R was performed in the Hemolung group after onset of ARDS. Histopathology, CTscans, systemic and pulmonary variables, and CO2 removal were examined. Results: Early application of ECCO2R therapy with Hemolung in spontaneously breathing sheep decreased PaCO2 significantly, while the device removed about 70mL of CO2 per minute. This did not result in lower minute ventilation in the Hemolung group. Lungpathology and CTscans did not show a difference between groups. Conclusion: In an ovine model of ARDS due to smoke inhalation and burn injury, early institution of ECCO2R in spontaneously breathing animals was effective in removing CO2 and in reducing PaCO2. However, it had no effect on reducing the severity of lung injury or mortality. Further studies are necessary to detail the interaction between extracorporeal CO2 removal and pulmonary physiology.