Evaluation of Neurophysiologic and Systematic Changes during Aeromedical Evacuation and en Route Care of Combat Casualties in a Swine Polytrauma Model

摘要

There is a dearth of knowledge about the effects of long range aero- medical evacuation on injured organs, as well as an emerging published database suggesting clinically significant adverse effects of hypobaria on even healthy tissues. Cabin pressure is equivalent to an altitude around 8,000ft. at which inspired oxygen is sufficient to maintain blood oxygen saturation above 90% in a healthy individual. In combat casualties with multiple injuries this could however compromise oxygen delivery and result in hypoxemia. Additionally, increase in altitude with concomitant decrease in atmospheric pressure allows gas expansion in body cavities. The volume of trapped gas expands by approximately 35% from sea level to an altitude of 8,000 feet. This can expose already vulnerable patients to severe complications. In light of this, a thorough investigation of the effects of hypobaria in clinical settings simulating the most important injury patterns encountered by combat casualties is necessary to optimize treatment efficacy and safety. During the first year of this project, the Naval Medical Research Center (NMRC) designed and built a chamber that can be de-pressurized to atmospheric pressure at 8,000ft. Chamber construction has been completed and swine experiments have been initiated. The NMRC Center for Hypobaric Experimentation, Simulation and Testing (CHEST) provides a unique platform for evaluation of long-range evacuation effects on physiology and therapeutic interventions in military relevant large animal combat injury models, which may contribute to optimization of combat casualty care and evacuation guidelines.