Evacuation

#### EVACUATION

J Trauma Acute Care Surg. 2018 Jul;85(1S Suppl 2):S68-S76

# Effect of hypobaria and hyperoxia during sepsis on survival and energy metabolism.

Choi M, Tamrakar P, Schuck P, Proctor J, Moore A, Asbury K, Fiskum G, Coksaygan T, Cross AS.

BACKGROUND: Injured warfighters air evacuated to tertiary medical care facilities are subjected to many stresses that may promote the development of sepsis. In this study, we tested the hypothesis that exposure to "in-flight" hypobaria and/or hyperoxia within 24 hours after onset of intra-abdominal infection in rats accelerates the development and/or severity of sepsis and neurologic injury in survivors.

METHODS: Sprague-Dawley rats underwent cecal ligation/puncture (CLP) or sham procedures. Twenty-four hours later, rats were then placed in hypobaric chambers for 6 hours and assigned to normobaric conditions and maintained at either 21% or 100% O2, or under hypobaric conditions (pressure equivalent to an altitude of 8,000 ft) but maintained under either 28% or 100% O2. Two days after CLP or sham, blood samples were obtained for cytokine levels, and mitochondria were isolated from the brain and heart of a subset of animals for analysis of mitochondrial oxygen consumption. Animals were also evaluated for neuromotor impairment before and 15 days postsurgery.

RESULTS: Among the 70 rats studied, 16.7% of CLP but none of the sham-treated rats died. All of the CLP but none of the sham rats had evidence of peritonitis at 2 days. Twenty percent (6 of 30) CLP rats undergoing hypobaria versus 12.5% (3 of 24) of CLP rats exposed to normobaria died (p = 0.715) while 12% (3 of 25) of CLP rats exposed to hyperoxia versus 20.7% (6 of 29) of CLP rats exposed to normoxia died (p = 0.48). The ratio of mitochondrial ATP-generating O2 consumption to resting respiration was higher in the CLP plus hypobaria under 100% compared with shams. The only difference in H2O2 production was observed in mitochondria from CLP rats exposed to hyperoxia under normobaric conditions. Composite neurologic scores obtained 15 days postinjury were lower than those at baseline for shams.

CONCLUSION: We conclude that neither "in-flight" hyperoxia nor hypobaria exacerbate sepsis or neurologic injury.

J Spec Oper Med. Summer 2018;18(2):79-85.

# Survey of casualty evacuation missions conducted by the 160th Special Operations Aviation Regiment during the Afghanistan conflict.

Redman T, Mayberry K, Mora A, Benedict B, Ross E, Mapp J, Kotwal R

BACKGROUND: Historically, documentation of prehospital combat casualty care has been relatively nonexistent. Without documentation, performance improvement of prehospital care and evacuation through data collection, consolidation, and scientific analyses cannot be adequately accomplished. During recent conflicts, prehospital documentation has received increased attention for point-of-injury care as well as for care provided en route on medical evacuation platforms. However, documentation on casualty evacuation (CASEVAC) platforms is still lacking. Thus, a CASEVAC dataset was developed and maintained by the 160th Special Operations Aviation Regiment (SOAR), a nonmedical, rotary-wing aviation unit, to evaluate and review CASEVAC missions conducted by their organization.

METHODS: A retrospective review and descriptive analysis were performed on data from all documented CASEVAC missions conducted in Afghanistan by the 160th SOAR from January 2008 to May 2015. Documentation of care was originally performed in a narrative after-action review (AAR) format. Unclassified, nonpersonally identifiable data were extracted and transferred from these AARs into a database for detailed analysis. Data points included demographics, flight time, provider number and type, injury and outcome details, and medical interventions provided by ground forces and CASEVAC personnel.

RESULTS: There were 227 patients transported during 129 CASEVAC missions conducted by the 160th SOAR. Three patients had unavailable data, four had unknown injuries or illnesses, and eight were military working dogs. Remaining were 207 trauma casualties (96%) and five medical patients (2%). The mean and median times of flight from the injury scene to hospital arrival were less than 20 minutes. Of trauma casualties, most were male US and coalition forces (n = 178; 86%). From this population, injuries to the extremities (n = 139; 67%) were seen most commonly. The primary mechanisms of injury were gunshot wound (n = 89; 43%) and blast injury (n = 82; 40%). The survival rate was 85% (n = 176) for those who incurred trauma. Of those who did not survive, most died before reaching surgical care (26 of 31; 84%).

CONCLUSION: Performance improvement efforts directed toward prehospital combat casualty care can ameliorate survival on the battlefield. Because documentation of care is essential for conducting performance improvement, medical and nonmedical units must dedicate time and efforts accordingly. Capturing and analyzing data from combat missions can help refine tactics, techniques, and procedures and more accurately define wartime personnel, training, and equipment requirements. This study is an example of how performance improvement can be initiated by a nonmedical unit conducting CASEVAC missions.