The use of venovenous extracorporeal membrane oxygenation in sheep receiving severe smoke inhalation injury

Smoke inhalation injury now represents the most frequent cause of death in burn patients, and accounts for 20-80 per cent of overall mortality. We have studied the use of extracorporeal membrane oxygenation (ECMO) to support sheep which have received lethal pulmonary smoke damage. The animals (n=19) received inhalation injury induced by insufflation with smoke derived from burning cotton delivered with a bee smoker. The treatment group, those placed on ECMO at the time of injury (n=6), were systemically heparinized and placed on a venovenous perfusion circuit consisting of a roller pump, membrane oxygenator and heat exchanger. Blood flow rate in the circuit approximated 20-25 per cent of cardiac output. The animals remained on partial venovenous bypass until the termination of the experiment 96h after injury. All animals in the treatment group survived. The control sheep (n=7) received inhalation injury alone and had a 100 per cent mortality (P=0.0015 ECMO vs. control). Ventilatory management of treatment and control groups followed an identical protocol. We have also studied a third group (n=6) composed of animals receiving inhalation injury with systemic heparinization but not ECMO. This group had a 66 per cent mortality at 96h. These studies suggest that partial venovenous ECMO may be a valuable form of adjunctive treatment in severe inhalation injury.