Technical Reports
A technical report is a technical document that records and disseminates methods and results from research studies and research, development, test, and evaluation (RDT&E) activities. Technical reports are USAARL's principal method of in-depth reporting on technical subjects that are of interest not only to the department, agency, or command sponsoring the work, but also to external groups and laboratories in government, academia, and industry. Technical reports may vary in type, to include technical reports that present the findings of research or analyses or that provide guidance or instruction on matters important to the DoD, journal articles (open access and embargoed text) that have been published under an open access agreement with the publisher or published under a Creative Commons license, conference proceedings that include whole collections of papers presented at a symposium or workshop, and conference papers that could include an individual paper, briefing charts, or a poster presented at a workshop or symposium. For inquiries related to USAARL's technical report(s), contact usarmy-usaarl-library@health.mil.
Featured Reports
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TITLE:Preliminary Field Evaluation of Assistive Devices on Carry Distance and Time During Two-Person Litter Transport Scenarios
AUTHOR(s):Stewart, A. S., Ballard, M. T., Robinette, A. M., Perkins, S. M., Prusia, M., Fjerstad, M., Watts, L., Oldham, R., Wagner, C., Arntzen, S., Brozoski, F., Barazanji, K., Madison, A. M., & Chancey, V. C.
ABBREVIATED ABSTRACT:Background: Evacuating casualties often relies on dismounted litter transport, a physically demanding task that can quickly drain a Soldier's grip strength. Assistive devices could shift the load to larger muscle groups, reducing muscle strain by distributing weight more evenly along the body. Previous USAARL lab-based research demonstrated assistive device use can allow simulated dismounted litter transport over farther distances in 2-person assisted litter carries than 4-person unassisted litter carries. As a follow-on effort to the lab-based simulated litter transport study, USAARL conducted a preliminary field-based study to evaluate assistive device use on litter bearer performance during 2-person litter carries.
Methods: U.S. and Dutch Service Members (SMs) participating in the Army Expeditionary Warrior Experiment were recruited and enrolled under a USAMRDC IRB approved protocol. Subjects (n = 12; 10 male, 2 female) were gender and height paired into 6 litter teams (2 subjects per team) to complete carries around a 160-meter (m) long course. Three litter carry conditions were tested: unassisted (UA), shoulder harness (SH) assisted, and wrist hooks (WH) assisted. Carry conditions were counterbalanced and separated by rest periods. Each attempt ended after 20 minutes (min) or upon releasing the litter due to fatigue of either subject. Total carry time and distance were measured and recorded at the end of the carry attempt.
Results: Average litter carries were 158.6 m and 2.36 min for UA, 1071.3 m and 15.8 min for SH, and 303.6 m and 4.34 min for WH. These 2-person carries showed similar trends as the previous lab-based study: both assistive devices showed improvements during assisted carries over UA carries; however, only SH was statistically significant compared to the other carry conditions.
Conclusions: This study built on the previous lab-based study, showing litter carry distance and time can be increased with assistive devices like the SH and WH by more than 6.5 and 1.8 times, respectively, in 2-person field litter carries. While these findings suggest assistive devices could benefit SMs, additional field testing and analyses are needed to fully evaluate the feasibility and practicality of the devices in operational settings through use of subjective, biomechanical, and physiological data. The next steps of this research aim to inform the development of solutions that reduce fatigue and ultimately enhance SM well-being and combat readiness.
KEYWORDS:litter carry, litter carriage, casualty transport, medical evacuation, stretcher, grip strength, litter bearer, assistive devices, CASEVAC, MEDEVAC
TITLE:Limitations Associated with Trasncranial Direct Current Stimulation for Enhancement: Considerations of Performance Tradeoffs in Active-Duty Soldiers (Reprint)
AUTHOR(s):Duffy, M. J., Feltman, K. A., Kelley, A. M., & Mackie, R.
ABBREVIATED ABSTRACT:Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method, popular due to its low cost, ease-of-application, and portability. As such, it has gained traction in examining its potential for cognitive enhancement in a diverse range of populations, including active-duty military. However, current literature presents mixed results regarding its efficacy and limited evaluations of possible undesirable side-effects (such as degradation to cognitive processes). To further examine its potential for enhancing cognition, a double-blind, randomized, sham-controlled, within-subjects design, was used to evaluate both online active-anodal and -cathodal on several cognitive tasks administered. Potential undesirable side effects related to mood, sleepiness, and cognitive performance, were also assessed. Active tDCS was applied for 30 min, using 2 mA, to the left dorsolateral prefrontal cortex with an extracephalic reference placed on the contralateral arm of 27 (14 males) active-duty Soldiers. We report mixed results. Specifically, we found improvements in sustained attention (active-anodal) for males in reaction time (p = 0.024, ?p2 = 0.16) and for sensitivity index in females (p = 0.013, ?p2 = 0.18). In addition, we found faster reaction time (p = 0.034, ?p2 = 0.15) and increased accuracy (p = 0.029, ?p2 = 0.16) associated with executive function (active-anodal and -cathodal), and worsened working memory performance (active-cathodal; p = 0.008, ?p2 = 0.18). Additionally, we found increased risk-taking with active-anodal (p = 0.001, ?p2 = 0.33). tDCS may hold promise as a method for cognitive enhancement, as evidenced by our findings related to sustained attention and executive function. However, we caution that further study is required to better understand additional parameters and limitations that may explain results, as our study only focused on anode vs cathode stimulation. Risk-taking was examined secondary to our main interests which warrants further experimental investigation isolating potential tradeoffs that may be associated with tDCS simulation.
KEYWORDS:working memory, attention, executive function, tDCS, active-duty Soldiers
TITLE:Methodology for Developing Realistic Patient Scenarios for Research Applications
AUTHOR(s):Kroening, L., Snyder, S., Molles, J., Toelle, R., Kinsler, R., Lloyd, A.
ABBREVIATED ABSTRACT:Introduction: The U.S. Army Aeromedical Research Laboratory's Enroute Care Group (ECG) Research Team has performed several research studies that require participants to provide care to simulated patients during data collection. These simulated patients must mimic human anthropometry, display injuries realistically, provide dynamic vital signs, respond to treatment, etc. ECG has developed a methodology for creating these patient scenarios to meet these requirements. Materials and Methods: Patient requirements are determined during early development of the research protocol, such as casualty evacuation category (urgent surgical, urgent, priority, or routine) and number of patients needed in each category. This decision is made with the input of a subject matter expert (SME), such as a Critical Care Flight Paramedic or Flight Surgeon, to determine realistic patient configurations in the medical evacuation platform being used. A data request form with detailed patient parameters is submitted to the Joint Trauma System (JTS) Department of Defense Trauma Registry. After receiving de-identified patient records from the JTS registry, the SME down-selects the records, extracts the essential clinical information, then uses it as the basic structure for the simulated patients. The team then designs the scenarios (e.g., decompensation events, alarms, responses to interventions) using available technology that meets the study objectives and programs them into the patient simulator software. The treatment responses of the simulated patients are customized within the software for added realism. The simulated patients are moulaged with the injury patterns from the JTS record summary, and tactical combat casualty care (TCCC) cards are created for each patient. Participants review the TCCC cards just prior to the start of data collection and begin treatment based on the TCCC information, injuries presented, and the live vital signs displayed on patient monitors. Treatments given during data collection are input into the simulator program by research team members remotely monitoring the scene so that patients respond to the treatments in real-time. Results: The results are realistic, customizable patient scenarios grounded in real-world events suitable for enroute care research and provider training. Conclusion: Over several studies, ECG has iteratively developed a method for customizing patient scenarios, allowing for realistic training during data collection.
KEYWORDS:methodology, patient simulation, critical care flight paramedics, CCFPs, medical evacuation, MEDEVAC, research, U.S. Army
TITLE:Assessment of Remote Patient Management System Clinical Monitoring in a Ground Simulation of an Airborne Casualty Evacuation Transport Environment
AUTHOR(s):Lloyd, A., Kinsler, R., Kroening, L., Snyder, S., Buono, Z. & Sieling-Mondora, N.
ABBREVIATED ABSTRACT:The Unmanned Aircraft Systems Medical Research Platform effort has the goal of developing a testbed system to support the study of remote control and monitoring of medical devices in flight environments. For this effort, the Telemedicine and Advanced Technology Research Center (TATRC) and the U.S. Army Aeromedical Research Laboratory (USAARL) have partnered to test medical devices in ground and flight environments. The Remote Patient Management System (RPMS), which includes the Thornhill Medical MOVES SLC patient monitor and ventilator, the NeuroWave AccuPump infusion pump, and the DocBox integration software, was tested. The RPMS underwent airworthiness release (AWR), ground, and flight testing. A limited end-user evaluation was also completed, where two flight surgeons were asked about the utility of the RPMS. Laboratory testing was completed on the RPMS, and a test AWR was granted. The RPMS was able to relay oxygen saturation data within an average 0.44% of the patient vital sign simulator and for non-invasive blood pressure it was accurate within 7.5%. However, the DocBox did not refresh the heart rate information, and showed a constant value for the testing. The participants found implementing treatments easy but found it difficult to know whether the patient received the intervention. The data will be used to identify key impacts to sensor, therapy, and communications functions that may impact the ability for the RPMS to perform adequately.
KEYWORDS:remote patient management, flight testing, medical device test and evaluation, DocBox, MEDEVAC, CASEVAC, telemedicine
TITLE:Choosing the Right Gear: A Guide to Physiological Devices for Monitoring Operator States of Aviators
AUTHOR(s):Warfighter Performance Group
ABBREVIATED ABSTRACT:The abundance of physiological monitoring devices available and in development can be overwhelming. Thus, this guide was developed to provide decision makers and non-experts with a resource to assist them in understanding what these various devices are measuring, how those measurements tie in to cognitive state, and what needs to be considered for using the devices in an operational setting. The focus here is on providing a basic understanding of what exactly each wearable measures. Some of the current states of individual technologies are discussed, but given the rapid pace of development in this area, less focus is given to this. This guide focuses on measures that are being explored within the aviation domain. Please be aware that new measures are being sought by researchers, so the measures presented here are not exhaustive.
KEYWORDS:wearables, aviators, physiological monitoring, performance, future vertical lift
TITLE:Effects of Hypoxia and Prolonged Visually Guided Performance on Dynamic Stereoscopic Depth Tracking and Related Tasks
AUTHOR(s):Temme, L., St. Onge, P., Bowers, B., Andres, K., McAtee, A., & Mackie, R.
ABBREVIATED ABSTRACT:Background: To maintain proper visual references, aviators depend on precise binocular depth perception technically called stereopsis. Defective stereopsis may degrade such aviation tasks as hover, taxiing, landing, formation flying, aerial refueling, and hoist and rescue operations. The increased prevalence of stereo displays in the cockpit creates the need for a better understanding of stereo vision in operational contexts. Hypothesis: Conventional static stereo acuity tests that rely on static stimuli are poor predictors of the dynamic stereo acuity needed for the sustained performance of demanding, real-world visual tasks. Specific Aims: Track dynamic stereo acuity over 2-minute epochs sampled periodically during volunteers' sustained performance of surrogate operational tasks to compare dynamic stereo acuity with conventional static stereo acuity under normoxic and a sustained normobaric hypoxic (14% oxygen) emulation of 10,000 feet above mean sea level.
Study Design: A multivariate, balanced, 2-factor, within-subject randomized experiment with 24 subject volunteers.
Vision performance metrics include, in addition to stereoscopic tracking, static stereo acuity, two-dimensional target tracking, vertical and horizontal fusional ranges. Results showed normobaric hypoxia degraded dynamic stereoscopic but not static stereoscopic vision.
KEYWORDS:stereoscopic vision, Stereoscopic depth tracking, hypoxia, aviation, horizontal fusional range, vertical fusional range, visual acuity
TITLE:Recommendations for the Development of a Spine Conditioning and Resiliency Program for the Prevention, Management, and Mitigation of Spinal Disorders in U.S. Army Rotary-Wing Aviators
AUTHOR(s):Madison, A., Novotny, B., Pederson, T., Pascoe, N., Stewart, A., Barazanji, K., & Chancey, V. C.
ABBREVIATED ABSTRACT:Spinal pain and injury are well documented in domestic and international military aviators, resulting in thousands of lost flight hours and aviator retention concerns. Spine-directed exercise training regimens have been identified and recommended for development by the North Atlantic Treaty Organization Human Factors and Medicine Research Task Group Panel 252 (NATO HFM RTG-252) as effective prevention and treatment countermeasures for degenerative cervical and lumbar spine anomalies experienced by military aviators. Several fellow NATO HFM RTG-252 panel member nations have developed comprehensive aircrew conditioning programs (ACPs) with general physical fitness and neck-specific training components. However, these have been primarily developed for aviators in jet and high-performance aircraft operational environments, with rotary-wing environment considerations and applications being secondary.
Aircraft vibration, helmet systems, and seat ergonomics differ between rotary-wing and fixed-wing environments, suggesting the need for a formalized and inclusive exercise regimen for U.S. Army rotary-wing aviators, which needs improvement.
The U.S. Army Aeromedical Research Laboratory (USAARL) reviewed published literature and data outcomes over the last 30 years from previous and ongoing neck and back exercise regimen studies, including fellow NATO panel members and U.S. Army approaches. The review also updated the knowledge regarding degenerative spinal mechanisms in military rotary-wing aviation operational environments. Additionally, updated epidemiological data were obtained regarding the incidence and prevalence of cervical and lumbar spinal disorders in the aviation population.
Based on literature review findings and NATO HFM RTG-252 panel recommendations, USAARL, in collaboration with clinicians at Carl R. Darnall Army Medical Center (CRDAMC) and Lyster Army Health Clinic (LAHC), has developed the framework for a detailed, multifaceted aircrew spine conditioning and resiliency program (ASCRP) intended for the prevention, management, and mitigation of both cervical and lumbar spinal disorders in U.S. Army rotary-wing aviators. The proposed ASCRP will include the following exercise strategies: strength and flexibility/mobility, activation, stabilization, and control, as well as strength and endurance components. The ASCRP is also designed to consist of home-based exercises, including a directed cervical spine resistance band intervention and operationally based exercises to be conducted pre-, during, and post-flight. Additionally, the regimen is unique in focusing on both cervical and lumbar spine disorders in
rotary-wing aviators. Furthermore, the regimen can be executed as a standalone, standardized initiative or integrated into a multi-disciplinary, holistic program that optimizes aviator health and performance.
Recommendations regarding the necessary steps and actions to transition the ASCRP into operational use in U.S. Army rotary-wing aviation units are provided. These interventions and exercises are initially recommended as best practices and will be down selected and finalized after validating the efficacy of the regimen.
KEYWORDS:cervical spine, lumbar spine, neck pain, back pain, rotary-wing, whole-body vibration, WBV, low back pain, LBP, pilots, aviator, aircrew, aircrew conditioning program, ASCRP, spinal disorder
TITLE:A Handbook for Choosing the Right Gear for Physiological Monitoring
AUTHOR(s):Warfighter Performance Group
ABBREVIATED ABSTRACT:This document is an abbreviated handbook to be used as a reference for individuals who do not have experience in physiological monitoring. This handbook provides basic overviews of different types of physiological monitoring available and some of the limitations of various products. The purpose is to help individuals make informed decisions regarding some of the products available on the market.
KEYWORDS:physiological monitoring, human performance
TITLE:Human Factors Analysis and Classification System as a Potential Confounder in Army Aviation Mishap Analysis
AUTHOR(s):Curry, I., & Lee, A.
ABBREVIATED ABSTRACT:Introduction: The U.S. Department of Defense has utilized the Human Factors Analysis and Classification System (HFACS) in its various iterations since 2004 to classify and codify the causation of military mishaps. The purpose of this study is to examine the likely accuracy of the HFACS coding of U.S. Army Aviation mishaps.
Methods: The U.S Army Combat Readiness Center (CRC) database was queried for the fiscal years (FY) 2012-2022, the class A and B aviation mishaps were collated with their associated HFACS codes, and the mishap narratives were examined by an expert panel of senior mishap investigators, aviators, and aeromedical practitioners. The resultant disparities between the CRC coding and the assessed causative factors with special reference to spatial disorientation (SD) were then examined.
Results: In the period under examination (FY 2012-2022) there were 184 class A and B helicopter mishaps recorded in the CRC database. Of those, 106 had HFACS version 7.0 codes assigned to them with 52 unique codes used. With specific reference to SD causation, only 3 of the 7 SD-related codes in HFACS version 7.0 were found to have been used; misinterpretation of instruments, misperception of changing environment, and SD. Combined, these amounted to 36 of the 537 codes used (6.7%). The expert analysis of the 106 mishaps coded showed 58 with no SD component (54.7%), 29 with SD as a contributory factor (27.4%), and 25 where SD was assessed as being causal (23.6%). By contrast, the HFACS coded SD causation in 4 of 106 (3.8%) mishaps.
Discussion: The review of CRC codes versus expert opinion suggests that the coding does include elements that are very common in SD mishaps but without the final step to assign an SD code to a specific mishap. Thus, the information being presented to Army aviation senior leadership is providing at best, an incomplete picture and at worst, a significant distortion of mishap causation. This erroneous information may have significant implications for policy making and is particularly dangerous in view of the Future Vertical Lift program currently underway in the U.S Department of Defense.
KEYWORDS:Human Factors Analysis and Classification System
TITLE:The United States Army Aeromedical Research Laboratory Virtual Reality Vection System
AUTHOR(s):Nagy, R., & Temme, L.
ABBREVIATED ABSTRACT:The present report describes and documents the U.S. Army Aeromedical Research Laboratory Virtual Reality Vection System (VRVS), a versatile, inexpensive tool to investigate, demonstrate, and characterize vection as a representative example of or type of spatial disorientation (SD). In aviation, SD refers to a pilot's failure to correctly sense the position, motion, and/or attitude of the aircraft with respect to the fixed coordinate system the Earth's surface and its gravitational vertical. That is, SD refers to the potentially catastrophic situation in which a pilot does not know where the aircraft is heading relative to the surface of the Earth. One example of SD is vection, which is the illusion of self-motion in an individual who is not moving. Since vection is a form of SD that can be reliably generated under controlled laboratory conditions, it is a convenient SD example for demonstrations as well as a powerful tool to study and characterize SD and its effects in general. The VRVS as described includes its components, software, hardware, and user interfaces. Tests and evaluations, conducted while creating the VRVS and reported here, demonstrate that the system does reliably provoke vection and thus SD. The VRVS includes two complementary methods for quantifying the presence and magnitude of vection. Moreover, the VRVS enables the simultaneous measurement of vection and symptoms of cybersickness, such as nausea.
KEYWORDS:Virtual Reality Vection System, VRVS, virtual reality, vection, spatial disorientation
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Last Modified Date: 2023-04-14