Abstract 10: The Intrathoracic Pressure Regulator Improves Hemodynamics and 24-Hour Survival in a Pediatric Porcine Model of Severe Hemorrhagic Shock
Background: Hemorrhagic shock is a common cause of mortality and morbidity in the pediatric population. A new device, the intrathoracic pressure regulator (ITPR), lowers intrathoracic pressure (ITP) and intracranial pressure, and increases venous return, cardiac output, and aortic pressure without the need for immediate fluid resuscitation. These mechanisms result in greater blood flow to vital organs and may delay hypovolemic shock and death. We hypothesized that the ITPR would improve hemodynamics and 24-hour survival in a pediatric porcine model of severe hemorrhagic shock.
Methods: Twenty isofluorane anesthetized piglets were subjected to a 50% total blood volume hemorrhage, stabilized and then randomized to 60 min of resuscitation with either the ITPR (9) or no treatment (11). The ITPR (Advanced Circulatory Systems Inc, St. Paul, MN) provides positive pressure ventilation and then lowers ITP to −9 mmHg during the expiratory phase. After 60 min, surviving piglets were auto-transfused, weaned from the ventilator and assessed and autopsied at 24 hours. Mean arterial pressures (MAP), cardiac index (CI), and arterial blood gases with lactate were recorded at 15 min intervals. Lung damage was assessed histologically. Results are reported as mean ± SEM.
Results: During the study, the MAP (mmHg) was significantly higher in the ITPR group (ITPR 60.8 ± 3.7 vs. 41.2 ± 4.6 controls; p<0.01). Mean CI (L/min/m2) was significantly higher in the ITPR group (ITPR 3.9 ± 0.24 vs. 2.5 ± 0.39 controls; p<0.01). Mean arterial pH was significantly higher (ITPR 7.26 ± 0.01 versus 7.15 ± 0.02 controls; p<0.001) and mean lactate levels (mmol/L) were significantly lower in the ITPR group (ITPR 3.5 ± 0.5 vs. 6.9 ± 0.9 controls; p<0.05). Lactate levels with the ITPR improved over the course of the study from 4.1 ± 0.5 at (at end of bleed) to 3.4 ± 0.5 (after 60 min of ITPR). Neurologically-intact 24 hour survival significantly improved with the ITPR (ITPR 9/9 vs 5/11 controls; p<0.02). No difference in wet to dry ratios, levels of atelectasis or qualitative histological analysis of lung tissue were observed between groups.
Conclusions: In this piglet model of hemorrhagic shock, the ITPR treatment safely and significantly reduced metabolic acidosis and improved MAP, CI and 24 hour survival rates.
- © 2010 by American Heart Association, Inc.