Supplemental oxygen attenuates the increase in wound bacterial growth during simulated aeromedical evacuation in goats

Abstract

Background Bacterial growth in soft tissue and open fractures is a known risk factor for tissue loss and complications in contaminated musculoskeletal wounds. Current care for battlefield casualties with soft tissue and musculoskeletal wounds includes tactical and strategic aeromedical evacuation (AE). This exposes patients to a hypobaric, hypoxic environment. In the present study, we sought to determine whether exposure to AE alters bacterial growth in contaminated complex musculoskeletal wounds and whether supplemental oxygen had any effect on wound infections during simulated AE. Methods A caprine model of a contaminated complex musculoskeletal wound was employed. Complex musculoskeletal wounds were created and inoculated with bioluminescent Pseudomonas aeruginosa. Goats were divided into three experimental groups: ground control, simulated aeromedical evacuation (AE), and simulated AE with supplemental oxygen (AE+O2). Simulated AE was induced in a hypobaric chamber pressurized to 8800 feet for 7 hours. Bacterial luminescence was measured using a photon counting camera at three timepoints: preflight (20 hours post surgery), postflight (7 hours from preflight and 27 hours post-surgery), and necropsy (24 hours from preflight and 44 hours post surgery). Results There was a significant increase in bacterial growth in the AE group compared to the ground control group measured postflight and at necropsy. Simulated AE induced hypoxia with oxygen saturation less than 93%. Supplemental oxygen corrected the hypoxia and significantly reduced bacterial growth in wounds at necropsy. Conclusions Hypoxia induced during simulated AE enhances bacterial growth in complex musculoskeletal wounds which can be prevented with the application of supplemental oxygen to the host.

Evaluation of Pseudomonas aeruginosa pathogenesis and therapeutics in military‐relevant animal infection models

“…The group further showed inefficiency of Dakin’s solution to reduce P. aeruginosa burden in a complex musculoskeletal wound [126]. Using this model, simulation of hypoxic conditions experienced by wounded soldiers during aeromedical evacuation results in stimulation of P. aeruginosa infection in wounded tissues [127]. In another study relevant to military trauma, sodium morrhuate injection into the left tibia of New Zealand white rabbits was used to create the bone/bone marrow defects, which were combined with bacterial infection to mimic infection within local blast wound trauma [128].…”

Monitoring During Transport

“…The long-term effects of these hypoxemic events are speculative but could have an impact in patients with head injuries, lung injury, and infections. 62,63 This review of adverse events during transport demonstrates the frequency and severity of cardiovascular and respiratory compromise seen during transport. Although none of these trials evaluated monitoring, each provides a list of undesirable outcomes, around which monitoring can be designed.…”

Records Review of Musculoskeletal Injuries in Aeromedical Evacuation Personnel

“…Flight stressors including hypoxia, barometric pressure, thermal stress, gravitational forces, noise, vibration, dehydration, and fatigue compound the physical stress of the providers functioning in this challenging environment. [13][14][15][16][17][18][19][20] Several past studies have focused on the ergonomic risk factors and MSIs associated with providers in civilian healthcare facilities. Back and joint pain are frequently reported, with 52% of nurses reporting back pain.…”