MSS10: INVESTIGATION OF OPTIMAL WARMING TECHNIQUES FOR THE HYPOTHERMIC TRAUMA PATIENT IN A SUS SCROTA MODEL
Hannah M Palmerton; Grace Pak; Bobby Zhang; James Williams; Beau Prey; Andrew Francis; Jason Bingham, MD; John McClellan, MD; Michael Lallemand, MD; Erik Roedel, MD; Madigan Army Medical Center
Objectives: In conjunction with trauma, hypothermia is associated with increased bleeding and worse outcomes. Return to temperature homeostasis is essential, yet the pace of rewarming is unproven and its influence unclear. We hypothesized that rate of rewarming influences outcomes, and evaluated its impacts on physiological responses to acute hemorrhage in a porcine model of trauma.
Methods: Adult Yorkshire mix pigs were randomized into three arms: control (n=8), rapid rewarming (n=8), slow rewarming (n=9). All animals underwent controlled hemorrhage of 35% blood volume. Hypothermia to 32oC for 1 hour was induced in experimental groups. Animals were resuscitated and rewarmed for a maximum of 3 hours either rapidly with a combination of endovascular heat exchange catheter, insulation shell, and warm water blankets (2oC/hour), or slowly with a standard military-issue warming blanket and shell (0.8oC/hour). Hemodynamic measurements, labs, and coagulation features (PTT, PT, INR, fibrinogen, TEG) were compared across time and between groups by mixed ANOVA analysis.
Results: The mean temperature reached between the fast (37.9 +/- 0.13oC) and slow groups (34.5 +/- 1.2oC) was significantly different (p < .01). Across time the animals in the slow group had a lower heart rate compared to the control group (95% CI 1.5 – 22.7, p = .024). The mean arterial pressure (MAP) was lower in both the slow (95% CI -.14 – 9.7, p = .058) and fast group (95% CI .83 – 10.9, p = .021) compared to control. There were no significant differences in lactate, pH, major electrolytes, coagulation, or mortality across time and between groups.
Conclusions: Using a large animal model of traumatic hemorrhage, our study supports the use of rapid rewarming as effective and safe for reversing hypothermia in the immediate post injury period. Future studies are needed to evaluate long-term outcomes and the feasibility of invasive temperature management in low resource environments.