An Evaluation of Aeromedical Evacuation Strategies Following Traumatic Brain Injury and Severe Blood Loss

Individuals experiencing severe polytrauma are typically transported to the highest level of care as soon as possible, including helicopter evacuation from remote and/or rural environments. However, several recent preclinical and clinical studies have suggested that aeromedical evacuation exacerbates central nervous system injury and inflammation, and potentially results in increased mortality, questioning the right time and conditions under which to fly. Twenty-four swine with moderate-to-severe rotational traumatic brain injury (TBI) and ∼40% blood loss were randomly assigned to standard (∼8500 feet), tactical (evasive maneuvering), or mock (stationary on ground) helicopter (U.S. Army Black Hawk; HH-60M model) evacuation 2 h post-injury, with standard recommended therapies initiated in-flight. Results indicated that tactical evacuation was associated with increased cerebral perfusion pressure and inflammation (IL-6) post-flight relative to the standard and mock evacuation profiles, even after statistically controlling for pre-flight trauma procedures. Although the overall mortality rate was ∼25%, indicating severe polytrauma, no differences in mortality were observed as a function of aeromedical evacuation scenarios. Primary biomarkers of hemorrhagic shock, traumatic brain injury, lung and kidney pathology were also negative for aeromedical evacuation effects. In summary, the medical benefits associated with immediate (i.e., within a few hours of injury) helicopter evacuation of severe polytrauma patients likely outweigh the few increased complications associated with flight, as the latter may only be present during more extreme helicopter evacuation scenarios. Additional studies are needed to address potential adjunctive therapies that can be administered pre-flight to minimize the potential adverse effects of tactical flight.