Direct Combat-related U.S. Army Aviation Injuries 2003-2014.

INTRODUCTION: The U.S. Army Aeromedical Research Laboratory (USAARL), a partner in the Joint Trauma Analysis for the Prevention of Injury in Combat (JTAPIC) partnership, conducted a series of retrospective reviews to investigate injuries sustained by occupants of U.S. Army rotary-wing aircraft involved in combat damage incidents. The reviews were conducted to provide occupant survivability information to the Aviation Survivability Development and Tactics team, an agency within the U.S. Army Aviation Center of Excellence. For these reviews, combat damage incidents that produced casualties were separated into direct events (i.e., events in which an enemy weapon system directly injured occupants) and indirect events (i.e., incidents in which occupants were injured as a result of a crash caused by the enemy weapon system). The previous USAARL reviews provided an overview of injuries sustained during direct and indirect events. The objective of this review was to conduct a detailed analysis of injuries occurring during direct events. MATERIALS AND METHODS: A descriptive retrospective review was conducted on injuries sustained by occupants of U.S. Army rotary-wing aircraft involved in combat damage incidents between 2003 and 2014. All Black Hawk, Apache, and Chinook combat aviation damage incidents for the study period were reviewed. Personnel casualty information from the Defense Casualty Information Processing System (DCIPS) was linked to combat damage incident information by matching the aircraft platform, incident date, and circumstantial information found in incident narratives. Injury information for personnel identified in DCIPS as being wounded in action was obtained from the JTAPIC partnership; injury data for personnel killed in action were retrieved from the Armed Forces Medical Examiner System. All injuries were coded using the Abbreviated Injury Scale (AIS). Descriptive statistics were used to describe the frequency and distribution of injuries to personnel involved in direct events. RESULTS: Overall, the extremities were the most commonly injured body regions, with lower extremities suffering more injuries than upper extremities. Penetrating injuries were identified as the primary injury mechanism for all body regions. Injuries to each AIS body region were predominantly of minor (AIS 1) and moderate (AIS 2) severity. CONCLUSIONS: Although injury severities were generally low (AIS 1 or AIS 2), the results of this effort indicate which body regions may benefit from additional protection during rotary-wing operations in hostile environments. The influence of occupant position within the aircraft and the use and effectiveness of personal protective equipment could not be effectively analyzed due to a lack of information.

COVID-19 MEDEVAC Best Practices: The Development of a Standardized Medical Operating Guideline.

COVID-19, a highly infectious virus, presents self-evident problems with regards to aeromedical transportation. Droplet size, proximity of caregiver from the patient, severity of upper and lower respiratory symptoms, personal protective equipment (PPE) and turbulence of airflow are factors which may influence the transmission of any biological agent aboard an air transport platform. Given the relatively confined space of rotary-wing MEDEVAC helicopters and the lack of structural barriers between flight crew and passengers, transmission risk is high, particularly when close contact under these conditions last beyond 15 minutes.1 Some authorities strongly recommend against the rotary-wing evacuation of COVID-19 patients when ground or fixed-wing transport is available due to the high risk of transmission.2,3.

Aircrew Performance and Safety While Using Protective Masks in Response to Coronavirus Disease.

INTRODUCTION: In response to the urgent need for safe aircrew respiratory protection due to the COVID-19 pandemic, three small descriptive evaluations were conducted with aircrew and air traffic controllers (ATC) that assessed the impact of mask use on safety and performance onboard rotary wing aircraft.METHODS: A series of evaluations assessed aircrew performance using the 3MTM Model 1860 N95 respiratory protection mask, two aviation-specific cloth mask prototypes, and a commercial off-the-shelf aviation-specific cloth mask. The series of evaluations included different sets of subjects consisting of up to five Black Hawk helicopter aircrew members, air traffic control (ATC), and 12 CH-47 aircrew members. The Modified Rhyme Test was used to measure speech intelligibility and was administered in the UH-60 among crewmembers of the same aircraft, between pilots of different aircraft, and between the pilots and ATC. Measures of workload, usability, comfort, and pulse oximetry were also administered.RESULTS: Results from the Modified Rhyme Test indicated that all subjects scored greater than 80% accuracy given the proper microphone positioning relative to the mask. With respect to workload, NASA-TLX total scores for the perform radio communications task was 50.83.DISCUSSION: Despite an elevated perceived degree of workload on the communications flight task, results from the speech intelligibility test indicated that performance was maintained within the acceptable range as defined by MIL-STD-1474E, Design Criteria Standard Noise Limit. This abbreviated evaluation suggests that the face masks tested are safe for use by helicopter aircrew under the conditions tested.Cave KM, Kelley AM, Feltman KA, Gerstner JA, Stewart JL, Crowley JS. Aircrew performance and safety while using protective masks in response to coronavirus disease. Aerosp Med Hum Perform. 2021; 92(4):274280.

Tactile cues in continuous operations: a preliminary study.

INTRODUCTION: Research has shown that tactile displays are an effective tool for augmenting spatial orientation and situation awareness information provided to aircraft operators. The tactile situation awareness system (TSAS) has been shown to improve flight performance in conditions of degraded visual environments and to safely maintain performance during hover over moving targets. The potential for the user to adapt and habituate to the stimulus of tactile display systems has not yet been investigated. METHODS: Four UH-60 current, rated aviators (all male) participated in the pilot study. Subjects completed four consecutive iterations of a 3-h flight profile consisting of 10 maneuvers, totaling 12 h of continuous flight. Flight performance, tactor information, responses to a discomfort questionnaire, and ratings of fatigue symptoms were recorded. RESULTS: The independent variable in all analyses was session (four levels). The results showed that performance per maneuver and proportion of stimulus cues (measure of response to cues) per maneuver were consistent across sessions using independent-samples Kruskal-Wallis tests. DISCUSSION: The findings of this preliminary assessment support the use of tactile displays (consistent with parameters of TSAS) in continuous operations since performance and proportion of stimulus cues presented was consistent over a period of 12 h. In conclusion, the system will require further experimental testing, but these preliminary findings do not suggest performance or response to be affected by any adaptation or habituation to the stimulus.

Modafinil as a replacement for dextroamphetamine for sustaining alertness in military helicopter pilots.

INTRODUCTION: Successful military aviation operations depend on maintaining continuous day-night operations. Stimulants are easy to use and popular for sustaining performance because their utility is not dependent upon environmental or scheduling modifications. Dextroamphetamine is authorized for use by the aircrews of all U.S. military services, but its potential for abuse and subsequent addiction is of aeromedical concern. Finding an alternative stimulant, such as modafinil, that displays a low affinity for dopamine uptake binding sites would prove extremely beneficial. This study sought to establish the efficacy and safety of modafinil during actual flying operations, thus providing the operational validity desired to approve the use of modafinil for helicopter flight operations. METHODS: During two, 40-h periods of sustained wakefulness, 18 helicopter pilots (17 men, 1 woman, mean years of age = 29.5) each completed 15 flights and other evaluations, during which they received 2 of 3 experimental conditions: 3 doses at 4-h intervals of modafinil (100 mg), dextroamphetamine (5 mg), or placebo. RESULTS: Statistical results showed that modafinil, like dextroamphetamine, maintained alertness, feelings of well-being, cognitive function, judgment, risk perception, and situation awareness of sleep-deprived aviators consistently better than placebo and without side effects of aeromedical concern. DISCUSSION: Like previous research, this study strongly suggests that both drugs can maintain acceptable levels of mood and performance during sleep deprivation. The results also confirm that modafinil is well tolerated and appears to be a good alternative to dextroamphetamine for countering the debilitating mood and cognitive effects of sleep loss during sustained operations.

Traumatic brain injury risk while parachuting: comparison of the personnel armor system for ground troops helmet and the advanced combat helmet.

Military paratroopers are inherently at risk for a variety of injuries when they jump, including traumatic brain injuries (TBIs). U.S. Army paratroopers rely on their ballistic helmets for protection against TBIs when jumping. Currently, two different helmets are available to Army paratroopers, that is, the personnel armor system for ground troops helmet and the advanced combat helmet. This study compared the incidence of self-reported, jump-related TBIs in a small sample of paratroopers (N = 585) using each type of helmet. Data were obtained from surveys of soldiers at Fort Bragg, North Carolina. The overall relative risk of sustaining a TBI while jumping was 2.3 times (95% confidence interval, 1.3-4.3) higher for personnel armor system for ground troops helmet users. Most of the increase in risk was accounted for by the most-minor TBIs (American Academy of Neurology grade 1 or 2 concussion).

How satisfied are soldiers with their ballistic helmets? A comparison of soldiers' opinions about the advanced combat helmet and the personal armor system for ground troops helmet.

Many factors are considered during ballistic helmet design, including comfort, weight, fit, and maintainability. These factors affect soldiers' decisions about helmet use; therefore, rigorous research about soldiers' real-life experiences with helmets is critical to assessing a helmet's overall protective efficacy. This study compared soldiers' satisfaction and problem experience with the advanced combat helmet (ACH) and the personal armor system for ground troops (PASGT) helmet. Data were obtained from surveys of soldiers at Fort Bragg, North Carolina. Ninety percent of ACH users were satisfied overall with their helmet, but only 9.5% of PASGT users were satisfied (p < 0.001). The most frequently reported problems for the ACH involved malfunctioning helmet parts. The most frequently reported problems for the PASGT involved discomfort. This analysis indicated that there was a strong soldier preference for the ACH over the PASGT, which could enhance its already superior protective qualities. It also demonstrated the usefulness of soldiers' assessments of protective equipment.

Upper extremity interaction with a helicopter side airbag: injury criteria for dynamic hyperextension of the female elbow joint.

This paper describes a three part analysis to characterize the interaction between the female upper extremity and a helicopter cockpit side airbag system and to develop dynamic hyperextension injury criteria for the female elbow joint. Part I involved a series of 10 experiments with an original Army Black Hawk helicopter side airbag. A 5(th) percentile female Hybrid III instrumented upper extremity was used to demonstrate side airbag upper extremity loading. Two out of the 10 tests resulted in high elbow bending moments of 128 Nm and 144 Nm. Part II included dynamic hyperextension tests on 24 female cadaver elbow joints. The energy source was a drop tower utilizing a three-point bending configuration to apply elbow bending moments matching the previously conducted side airbag tests. Post-test necropsy showed that 16 of the 24 elbow joint tests resulted in injuries. Injury severity ranged from minor cartilage damage to more moderate joint dislocations and severe transverse fractures of the distal humerus. Peak elbow bending moments ranged from 42.4 Nm to 146.3 Nm. Peak bending moment proved to be a significant indicator of any elbow injury (p = 0.02) as well as elbow joint dislocation (p = 0.01). Logistic regression analyses were used to develop single and multiple variate injury risk functions. Using peak moment data for the entire test population, a 50% risk of obtaining any elbow injury was found at 56 Nm while a 50% risk of sustaining an elbow joint dislocation was found at 93 Nm for the female population. These results indicate that the peak elbow bending moments achieved in Part I are associated with a greater than 90% risk for elbow injury. Subsequently, the airbag was re-designed in an effort to mitigate this as well as the other upper extremity injury risks. Part III assessed the redesigned side airbag module to ensure injury risks had been reduced prior to implementing the new system. To facilitate this, 12 redesigned side airbag deployments were conducted using the same procedures as Part I. Results indicate that the re-designed side airbag has effectively mitigated elbow injury risks induced by the original side airbag design. It is anticipated that this study will provide researchers with additional injury criteria for assessing upper extremity injury risk caused by both military and automotive side airbag deployments.

The effect of frontal air bags on eye injury patterns in automobile crashes.

OBJECTIVE: To investigate eye injuries resulting from frontal automobile crashes and to determine the effects of frontal air bags. METHODS: The National Automotive Sampling System database files from January 1, 1993, through December 31, 1999, were examined in a 3-part study that included an investigation of 22 236 individual crashes that occurred in the United States. A new 4-level eye injury severity scale that quantifies injuries based on recovery time, need for surgery, and possible loss of sight was developed. RESULTS: Of all occupants who were exposed to an air bag deployment, 3% sustained an eye injury. In contrast, 2% of occupants not exposed to an air bag deployment sustained an eye injury. A closer examination of the type of eye injuries showed that there was a statistically significant increase in the risk of corneal abrasions for occupants who were exposed to an air bag compared with those who were not (P =.03). Of occupants exposed to an air bag deployment, 0.5% sustained a corneal abrasion compared with 0.04% of occupants who were not exposed to an air bag. CONCLUSIONS: Using the new injury levels, it was shown that although occupants exposed to an air bag deployment had a higher risk of sustaining minor eye injuries, the air bag appears to have provided a beneficial exchange by reducing the number of severe eye injuries.

Computer modeling of airbag-induced ocular injury in pilots wearing night vision goggles.

BACKGROUND: Airbags have saved lives in automobile crashes for many years and are now planned for use in helicopters. The purpose of this study was to investigate the potential for ocular injuries to helicopter pilots wearing night vision goggles when the airbag is deployed. METHODS: A nonlinear finite element model of the human eye was created. Ocular structures such as the fatty tissue, extraocular muscles, and bony orbit were included. The model was imported into Madymo (Mathematical Dynamical Models) and used to determine the worst-case position of a helicopter pilot wearing night vision goggles. This was evaluated as the greatest Von Mises stress in the eye when the airbag was deployed. RESULTS: The worst-case position was achieved by minimizing the distance between the eyes and goggles, having the occupant look directly into the airbag, and making initial contact with the airbag halfway through its full deployment. Simulations with the goggles both remaining fastened to and breaking away from the aviator helmet were performed. Finally, placing a protective lens in front of the eyes was found to reduce the stress to the eye but increase the force experienced by the surrounding orbital bones. CONCLUSION: The finite element model of the eye proved effective for evaluating the experimental parameters.