Abstract 203: Measurement of Cardiac Function in a Porcine Model of Cardiac Arrest Due to Massive Exsanguination
Background: While extremity hemorrhage can be stymied with a well placed tourniquet, vascular injury within the thorax and abdomen is not amenable to direct compression. Uncontrolled, noncompressible torso hemorrhage (NCTH) and the resultant cardiac arrest (CA) may account for up to 80% of preventable deaths in combat. We developed a porcine model of CA to test novel surgical interventions and are reporting measures of cardiovascular function during a simulated NCTH.
Methods: Ten anesthetized Yorkshire pigs underwent tracheostomy, arterial and central line placement. Animals were awakened and sedated with midazolam titrated to a bispectral index of 75 ± 5. Spontaneously breathing, the animals were subjected to a computerized hemorrhage of 80% total blood volume (TBVH) over 20 minutes or until death, defined as mean arterial pressure (MAP)=0 mmHg and etCO2<10. During hemorrhage, if minute ventilation decreased 25% from baseline (BL) for >20 seconds, volume control ventilation was initiated. The Millar MPVS Ultra system continuously collected left ventricular (LV) and descending aortic pressures, as well as LV volume data via indwelling catheters. A repeated measures one-way ANOVA with Tukey’s procedure was performed on data collected at BL, 25%, 44%, 62% TBV hemorrhage, and CA, defined as a MAP<20 mmHg. Data are presented as means±SEM.
Results: Weight was 63.8±2.8kg. TBVH at CA was 2941±130ml (71.0±1.5%). Time to CA was 18:22±00:40min. In Table 1, * denotes a significant change (p<0.05) in a variable from previous hemorrhage phase as marked by #.
Conclusions: We developed a porcine model of CA secondary to exsanguination. We found that despite decreasing left ventricular volumes and pressures, cardiac contractility and conduction system function were maintained throughout hemorrhage. This suggests that lifesaving interventions (such as endovascular aortic balloon occlusion and extracorporeal life support) may be possible despite profound hypovolemia.
- © 2013 by American Heart Association, Inc.