A MURINE MODEL OF COMBINED BURN AND SMOKE INJURY USING A NOVEL SMOKE INHALATION CHAMBER.

Severe pulmonary dysfunction after smoke inhalation remains a leading cause of death in burn patients. Current understanding of the molecular mechanism behind the observed physiology is limited. We have developed a murine model using a uniquely designed inhalation chamber which can be used to further characterize the pathophysiologic state of the lungs in both isolated inhalation and combined injuries. The inhalation unit is comprised of combustion, gas mixing and inhalation chambers, and is equipped with multiple access ports for smoke sampling and chamber monitoring. A meter-controlled vacuum pump supplies continuous ambient airflow (30 L/min). Dose titration experiments were conducted and conditions were standardized by continuous smoke sampling using a low flow vacuum source, a filter apparatus and an impinger. Total suspended particles (TSP) were calculated in mg/m3 and demonstrated a linear rise with increase sample. In the inhalation chamber, O2 levels remained above an FIO2 of 18.9 with a constant temperature of 23°C. Soluble smoke extract was analyzed using gas chromatography. Following standardization, female C57BL/6J mice were subjected to a 10 minute exposure of wood smoke followed by arterial blood gas analysis at a set time interval. Peak serum carbon monoxide levels reached 43.9% immediately after exposure and declined to 2% at 50 minutes. In subsequent experiments, mice were given either the standard inhalation exposure or an 18% TBSA burn vs. combined injury which was followed by tissue collection at 3 hours and 1 day post-injury. Furthermore, histopathologic examination of the lungs revealed vacuolization, cilia flattening and areas of desquamation in the bronchiolar epithelia of both the burn and combined injury groups. Additionally, whole body phlethysmography was performed at various times post-injury. This model provides a means to further characterize the molecular mechanism of lung injury after a combined burn and inhalation injury.Figure