Military Training Environment Research Articles

Cumulative Blast Impulse Is Predictive for Changes in Chronic Neurobehavioral Symptoms Following Low Level Blast Exposure during Military Training.

Cumulative low-level blast exposure during military training may be a significant occupational hazard, increasing the risk of poor long-term outcomes in brain function. US Public Law 116-92 section717 mandates that US Department of Defense agencies document the blast exposure of each Service member to help inform later disability and health care decisions. However, which empirical measures of training blast exposure, such as the number of incidents, peak overpressure, or impulse, best inform changes in the neurobehavioral symptoms reflecting brain health have not been established. This study was approved by the US Army Special Operations Command, the University of North Carolina at Chapel Hill, and the VA Puget Sound Health Care System. Using methods easily deployable across different organizational structures, this study sought to identify and measure candidate risk factors related to career occupational blast exposure predictive of changes in neurobehavioral symptom burden. Blast dosimetry-symptom relationships were first evaluated in mice and then tested in a military training environment. In mice, the righting time neurobehavioral response was measured after exposure to a repetitive low-level blast paradigm modeled after Special Operations training. In the military training environment, 23 trainees enrolled in a 6-week explosive breaching training course, 13 instructors, and 10 Service member controls without blast exposure participated in the study (46 total). All participants provided weekly Neurobehavioral Symptom Inventory (NSI) surveys. Peak blast overpressure, impulse, total number of blasts, Time in Low-Level Blast Occupation, and Time in Service were analyzed by Bayesian analysis of regression modeling to determine their probability of influence on the post-training symptoms reported by participants. We tested the hypothesis that cumulative measures of low-level blast exposure were predictive of changes in neurobehavioral symptoms. In mice, repetitive blast resulted in reduced righting times correlated with cumulative blast impulse. In Service members, peak blast overpressure, impulse, total number of blasts, Time in Low-Level Blast Occupation, and Time in Service all showed strong evidence of influence on NSI scores after blast exposure. However, only models including baseline NSI scores and cumulative blast impulse provided significant predictive value following validation. These results indicate that measures of cumulative blast impulse may have utility in predicting changes in NSI scores. Such paired dosimetry-symptom measures are expected to be an important tool in safely guiding Service members' occupational exposure and optimizing force readiness and lethality.

Force plate assessments in reconnaissance marine training company

The ability to obtain dynamic movement assessments using force plate technology holds the promise of providing more detailed knowledge of the strength, balance and forces generated by active-duty military personnel. To date, there are not well-defined use cases for implementation of force plate assessments in military training environments. We sought to determine if force plate technology assessments could provide additional insights, related to the likelihood of graduation, beyond that provided by traditional physical fitness tests (PFT’s), in an elite Marine training school. Serial force plate measures were also obtained on those Marines successfully completing training to determine if consistent measures reflecting the effects of training on muscle skeletal load-over-time could be accurately measured. A pre-training force plate assessment performed in 112 Marines did not predict graduation rates. For Marines who successfully completed the course, serial measures obtained throughout training were highly variable for each individual and no firm conclusions could be drawn related to load imposed or the fitness attained during training.

Acute Hearing Deficits associated with Weapons Exposure inSection734 Blast Overpressure Study (BOS).

This prospective, multi-site, observational study describes ongoing efforts in support of the Fiscal Year 2018 National Defense Authorization Act (NDAA) Section734 Blast Overpressure Study (BOS) to identify the acute effects impulse and blast exposure have on hearing abilities of the Warfighter in various military training environments. Hearing thresholds, a binaural tone detection task, and auditory symptoms were collected before and immediately following weapons exposure across nine military training environments from January 2020 to October 2022. An additional 25 non-exposed control participants also completed the behavioral test battery. A boothless audiometer was used to measure hearing ability in the field. Sound level meters were attached on-body to record the exposure environment throughout training. Mean threshold change for the blast-exposed group was worse than the control group. Of the 188 blast-exposed participants, 23 experienced a temporary threshold shift (TTS) acutely after exposure. A decrease in binaural tone detection performance and increased symptom severity was found when comparing blast-exposed participants with a TTS versus those without a significant change in hearing. A complex but consistent relationship between measured exposure level (LAeq8hr) and the magnitude of the resulting TTS is suggested in the available data. Recent discussions on Section734 studies examining the effects of repetitive blast exposure have indicated that hearing-related issues were a critical problem that needed additional research. Study outcomes provide highly repeatable results across various weapons systems with hazardous blast exposure. This standardized set of hearing assessment tools for evaluating acute effects of noise under field conditions has been critically important in improving our understanding of TTS in prospective human subject research.

Factors Associated With Concussion During Combatives Activities In A Military Training Environment

Factors Associated With Concussion During Combatives Activities In A Military Training Environment

Monitoring cognitive function in the fatigued warfighter: A rapid review of cognitive biomarkers.

Decreases in cognitive function impair occupational performance, reduce occupational safety, and increase musculoskeletal injury risk. The aim of this paper was to identify measures that may be used to monitor cognitive function in the warfighter. A rapid review. A rapid search of Academic Search Complete, MEDLINE, PsycINFO, and SPORTSDiscus databases was conducted. original peer reviewed research articles, written in English, published between 2002 and 2022, and using human participants with no health issues in military training environments or active service. Of the 248 articles screened, 58 full-text articles were assessed for eligibility and 29 included in the review. Of these, 16 papers presented data from multi-stressor military training environments, or experimental studies where simulated military tasks were being performed. Thirteen papers focused on an aspect of military work and the implications for cognitive function (i.e., physical load, periods of extended wakefulness or fatigue, and hypoxic conditions). The domains of cognitive function that were assessed (i.e. vigilance, reaction time, working memory, situational awareness, and decision-making) were somewhat consistent among studies. Prolonged exposure to high-stress military environments compromises multiple aspects of cognitive function. These findings highlight the need for a suite of biomarkers to monitor cognitive function and assess the ability of military personnel to attend to and process mission-critical information and make appropriate decisions on the battlefield and other high-stress environments. Our findings suggest that a suite of common tests may provide useful information about cognitive function in the warfighter.

Physiological biomarker monitoring during arduous military training: Maintaining readiness and performance.

Physiological and psychological stressors can degrade soldiers' readiness and performance during military training and operational environments. Integrative and holistic assessments of biomarkers across diverse human performance optimization domains during multistressor training can be leveraged to provide actionable insight to military leadership regarding service member health and readiness. A broad categorization of biomarkers, to include biochemical measures, bone and body composition, psychometric assessments, movement screening, and physiological load can be incorporated into robust analytical pipelines for understanding the complex factors that impact military human performance. In this perspective commentary we overview the rationale, selection, and methodologies for monitoring biomarker domains that are relevant to military research and specifically highlight methods that have been incorporated in a research program funded by the Office of Naval Research, Code 34 Biological and Physiological Monitoring and Modeling of Warfighter Performance. The integration of screening and continuous monitoring methodologies via robust analytical approaches will provide novel insight for military leaders regarding health, performance, and readiness outcomes during multistressor military training.

0913 Evaluation of a Single-Session Sleep Intervention for Air Force Trainees

Abstract Introduction Sleep insufficiency is highly prevalent in military personnel and has detrimental impacts on operational readiness and health. Sleep health across this population does not appear to have improved despite targeted health promotion programs and efforts to bolster evidence-based tertiary care for sleep disorders. There is some evidence that problematic sleep may emerge in early military training environments and persist throughout a service member’s career. Approximately 37,000 personnel complete Air Force (USAF) technical training each year to learn job-specific skills. The purpose of the present study was to assess the effectiveness of a single-session, group-based sleep intervention in USAF Technical Training. Methods A brief (40-min) intervention incorporating behavioral sleep medicine interventions and motivational interviewing was developed and tailored for the target population. Three military units were assigned to receive either the brief sleep intervention (n = 203) or an active control group receiving a brief tobacco intervention (n = 118). Students were queried at two weeks post-intervention to assess their sleep time and quality using the Self-Assessment of Sleep Survey-Split (SASS-Y). Participants included 321 USAF technical school students (Mean age = 21), and the majority identified as male (82%), White (67%), and non-Hispanic (75%). Propensity-score-weighted multivariable logistic regression was utilized to compare the sleep outcomes between intervention and control groups at follow-up. Results At follow-up, students in the sleep intervention were significantly more likely to report sleeping > 6 hours per night on weekdays (OR = 1.49, p < .001) and more likely to endorse “Good” or “Very Good” sleep quality (OR = 1.50, p = .032) as compared to the control group. Follow-up results also showed that 69.2% of students in the sleep intervention group reported having engaged in the self-selected positive sleep ‘Action Step’ they chose and wrote down during the intervention. Conclusion This is, to our knowledge, the first study to design and test a brief motivational interviewing and behavioral sleep intervention in USAF technical training. Results suggest that a single-session, group-level intervention can promote behavioral changes and improve sleep health. Future efforts should consider low-touch additions (e.g., text messaging) to support the durability of intervention effects. Support (if any)

Musculoskeletal injuries in US Air Force Tactical Air Control Party trainees: an 11-year longitudinal retrospective cohort study and presentation of a musculoskeletal injury classification matrix

IntroductionLittle is known of the epidemiology of musculoskeletal injuries (MSKIs) in US Air Force Special Warfare (AFSPECWAR) Tactical Air Control Party trainees. The purpose of this longitudinal retrospective cohort study...

Changes in eating pathology symptoms during initial military training in men and women and associations with BMI and injury risk

Nutritional fitness, which comprises food choices, meal timing, and dietary intake behaviors, is an important component of military service member health and performance that has garnered recent attention. This study utilized generalized linear mixed effects modeling (GLMM) to investigate changes in eating pathology symptoms in men and women during initial military training (Marine Corps Officer Candidates School (OCS)). Associations among eating pathology, musculoskeletal injury risk and BMI were also assessed. This investigation includes data from the Eating Pathology Symptoms Inventory (EPSI) and BMI at the start of OCS (n = 598: Male n = 469, Female n = 129) and end of the 10-week program (n = 413: Male n = 329, Female n = 84), and injury surveillance throughout. At baseline, female candidates presented with greater body dissatisfaction, binge eating, purging, and restricting, but lower negative attitudes toward obesity compared to male candidates (p < 0.001). Eating symptoms changed during military training indicated by decreased body dissatisfaction in women (p = 0.003), decreased excessive exercise and negative attitudes toward obesity in men (p < 0.001), decreased cognitive restraint (p < 0.001), restricting (p < 0.001), purging (p = 0.013), and muscle building (p < 0.001) and increased binge eating (p < 0.001) in both sexes. Changes in restricting were significantly related to changes in BMI during training (p < 0.05). The likelihood of future injury was 108 % higher in female candidates than males and decreased by 5 % for each unit increase in excessive exercise. Eating attitudes and behaviors change during military training environments and are associated with military health and readiness outcomes including BMI and injury risk.

Developing an Evidence-Based Military Auditory Fitness-for-Duty Standard Based on the 80-Word Modified Rhyme Test.

One important function of military audiology is to conduct evaluations of service members (SMs) with hearing loss to ensure they are fit for deployment in dangerous operational environments. The objective of this study was to establish evidence-based auditory fitness-for-duty criteria based on speech-in-noise performance on the 80- and 160-word clinical versions of the Modified Rhyme Test (MRT 80 and MRT 160 ). Approximately 2400 SMs with various levels of hearing loss were recruited to complete the MRT 80 in conjunction with their annual hearing conservation evaluations. These SMs were also asked to perform one or more operationally-relevant listening tasks based on audio recordings made in highly realistic military training environments. The scores on these tests were compared to determine how well a proposed cutoff criterion for the MRT 80 was able to identify individuals who are hard of hearing with an exceptionally high risk of abnormally poor performance on operationally-relevant hearing tasks. The results show that a cutoff criterion that combines the percent correct score on two lists of the MRT 80 (i.e. MRT 160 ) with information about the better-ear threshold at 2 kHz is generally able to separate listeners with hearing loss into those who are likely to perform relatively well on operational listening tests and those who are likely to perform poorly on these tasks. This is consistent with current military acquisition standards, which identify the MRT as the preferred test for evaluating speech intelligibility for radios, headsets, and other communication equipment. It is also consistent with prior studies conducted in high-fidelity military simulations which have shown a significant correlation between MRT performance and operational outcomes. The proposed selection criteria, along with the new hearing profile standards that were recently adopted by the US Army, appear to provide an effective evidence-based methodology for identifying those SMs with hearing loss who are most at risk for poor performance on hearing-critical military tasks.

Quantification of Recruit Training Demands and Subjective Wellbeing during Basic Military Training.

Purpose: Assess and describe the physical demands and changes in subjective wellbeing of recruits completing the 12 week Australian Army Basic Military Training (BMT) course. Methods: Thirty-five recruits (24.8 ± 6.8 y; 177.4 ± 10.1 cm, 75.6 ± 14.7 kg) consented to daily activity monitoring and weekly measures of subjective wellbeing (Multi-component Training Distress Scale, MTDS). The physical demands of training were assessed via wrist worn activity monitors (Actigraph GT9X accelerometer). Physical fitness changes were assessed by push-ups, sit-ups and multi-stage shuttle run in weeks 2 and 8. Results: All objective and subjective measures significantly changed (p < 0.05) across the 12 week BMT course. In parallel, there was a significant improvement in measures of physical fitness from weeks 2 to 8 (p < 0.001). The greatest disturbance to subjective wellbeing occurred during week 10, which was a period of field training. Weeks 6 and 12 provided opportunities for recovery as reflected by improved wellbeing. Conclusions: The physical demands of training varied across the Australian Army 12 week BMT course and reflected the intended periodization of workload and recovery. Physical fitness improved from week 2 to 8, indicating a positive training response to BMT. Consistent with findings in sport, wellbeing measures were sensitive to fluctuations in training stress and appear to have utility for individual management of personnel in the military training environment.

Monitoring work and training load in military settings – what’s in the toolbox?

ABSTRACT Military personnel are required to complete physically demanding tasks when performing work and training, which may be quantified through the physical stress imposed (external load) or the resultant physiological strain (internal load). The aim of this narrative review is to provide an overview of the techniques used to monitor work and training load in military settings, summarise key findings, and discuss important practical, analytical, and conceptual considerations. Most investigations have focused upon measuring external and internal load in military training environments; however, limited data exist in operational settings. Accelerometry has been the primary tool used to estimate external load, with heart rate commonly used to quantify internal load. Supplemental to heart rate, psychophysiological and biochemical measures have also been investigated to elucidate aspects of internal load. Broadly, investigations have revealed that military training requires personnel to perform relatively large volumes of physical activity (e.g. averaging ∼15,000 steps·day−1) of typically low-moderate intensity activity (<6 MET), although considerable temporal and inter-individual variability is observed from these gross mean estimates. There are limitations associated with these measures and, at best, estimates of external and internal load can only be inferred. These limitations are particularly pertinent for military tasks such as load carriage and manual material handling, which often involve complex activities performed individually or in teams, in a range of operational environments, with multiple layers of protection, over a protracted duration. Comprehensively quantifying external and internal loads during these functional activities poses substantial practical and analytical challenges.

Eyeblink Detection in the Field: A Proof of Concept Study of Two Mobile Optical Eye-Trackers

ABSTRACTIntroductionHigh physical and cognitive strain, high pressure, and sleep deficit are part of daily life for military professionals and civilians working in physiologically demanding environments. As a result, cognitive and physical capacities decline and the risk of illness, injury, or accidents increases. Such unfortunate outcomes could be prevented by tracking real-time physiological information, revealing individuals’ objective fatigue levels. Oculometrics, and especially eyeblinks, have been shown to be promising biomarkers that reflect fatigue development. Head-mounted optical eye-trackers are a common method to monitor these oculometrics. However, studies measuring eyeblink detection in real-life settings have been lacking in the literature. Therefore, this study aims to validate two current mobile optical eye-trackers in an unrestrained military training environment.Materials and MethodThree male participants (age 20.0 ± 1.0) of the Swiss Armed Forces participated in this study by wearing three optical eye-trackers, two VPS16s (Viewpointsystem GmbH, Vienna, Austria) and one Pupil Core (Pupil Labs GmbH, Berlin, Germany), during four military training events: Healthcare education, orienteering, shooting, and military marching. Software outputs were analyzed against a visual inspection (VI) of the video recordings of participants’ eyes via the respective software. Absolute and relative blink numbers were provided. Each blink detected by the software was classified as a “true blink” (TB) when it occurred in the software output and the VI at the same time, as a “false blink” (FB) when it occurred in the software but not in the VI, and as a “missed blink” (MB) when the software failed to detect a blink that occurred in the VI. The FBs were further examined for causes of the incorrect recordings, and they were divided into four categories: “sunlight,” “movements,” “lost pupil,” and “double-counted”. Blink frequency (i.e., blinks per minute) was also analyzed.ResultsOverall, 49.3% and 72.5% of registered eyeblinks were classified as TBs for the VPS16 and Pupil Core, respectively. The VPS16 recorded 50.7% of FBs and accounted for 8.5% of MBs, while the Pupil Core recorded 27.5% of FBs and accounted for 55.5% of MBs. The majority of FBs—45.5% and 73.9% for the VPS16 and Pupil Core, respectively—were erroneously recorded due to participants’ eye movements while looking up, down, or to one side. For blink frequency analysis, systematic biases (±limits of agreement) stood at 23.3 (±43.5) and −4.87 (±14.1) blinks per minute for the VPS16 and Pupil Core, respectively. Significant differences in systematic bias between devices and the respective VIs were found for nearly all activities (P < .05).ConclusionAn objective physiological monitoring of fatigue is necessary for soldiers as well as civil professionals who are exposed to higher risks when their cognitive or physical capacities weaken. However, optical eye-trackers’ accuracy has not been specified under field conditions—especially not in monitoring fatigue. The significant overestimation and underestimation of the VPS16 and Pupil Core, respectively, demonstrate the general difficulty of blink detection in the field.

The Benefit of Mental Skills Training on Performance and Stress Response in Military Personnel.

Mental skills training (MST) has been suggested to reduce stress in civilian and athletic populations, however, whether these techniques and practices transfer to a military population are unknown. Therefore, the purpose of this study was to evaluate two MST programs against a baseline condition, training-as-usual (TAU), during an intense, active-duty, military training environment. Two hundred and three Marines enrolled in the United States Marine Corps’ Basic Reconnaissance Course participated in this effort (n = 203; age = 22.7 ± 3.3 years; height = 178 ± 6.35 cm; weight = 97.7 ± 8.3 kg; Mean ± SD). Each Marine was assigned to one of three groups, Mindfulness-Based Mind Fitness Training (MMFT), General Mental Skills Training (GMST), or TAU. Operational and cognitive performance measures, as well as, physiological metrics were obtained across three training phases (phase 1–3). Furthermore, phase 3 was sub-divided into pre-ambush, ambush and post-ambush time points. Significant group × time interactions were found for the total number of errors committed on the sustained attention response task (p = 0.004); as well as, plasma cortisol (p < 0.0001) and insulin-like growth factor-1 (IGF-1; p < 0.0001). There were mixed results between groups on operational performance tasks with the MST groups tending to perform better than TAU the more time participants had with MST instruction. During ambush, the differences among groups were especially pronounced for measures of information processing that one would expect MST to enhance: coordinates recall, plot time, and plot accuracy (p < 0.001), with improvements ranging from 24.7 to 87.9% for the MST conditions when compared to TAU. These data demonstrate that independent of the specific type of MST program, the fundamental characteristics of stress regulation embedded within each MST program may enhance performance and cognitive function during time of heightened stress.

U.S. Soldiers and Foreign Language School: Stressors and Health.

While previous studies have examined the stress of the military training environment, studies have not systematically examined the stress associated with attending the Defense Language Institute Foreign Language Center (DLIFLC). Service members assigned to DLIFLC endure intense academic pressure to succeed while meeting military requirements. Thus, not only are traditional academic stressors likely to be of concern but there are other academic and military-related stressors that have to managed by students. The goal of the present study was to characterize the stressors facing military students, document their mental health status and well-being, and identify mitigating factors such as coping, social support, time management, and the classroom environment. Data were obtained from a cross-sectional survey administered in March of 2016. Study participants were 759 active-duty U.S. soldiers enrolled in DLIFLC, with a consent rate of 87.7%. Surveys were administered in classroom settings. Survey topics included demographics, student experience (e.g., classroom hours, stressors), mental health (e.g., depression, anxiety, hazardous alcohol use) and burnout, and mitigating factors (e.g., coping, social support, time management, classroom environment). Multiple logistic regressions were used to identify which variables in the predictor set were significantly associated with each of the five outcomes while controlling for the presence of all other variables. In terms of behavioral health, 7.2% met screening criteria for depression, 9.4% for anxiety, and 17.1% for hazardous alcohol use; 43.4% reported high/very high levels of burnout. About one-third of the sample who had taken a test failed at least one (32.2%). In terms of common stressors more than half reported high or very high-stress levels from meeting academic expectations, not getting enough sleep, and pressure to succeed from civilian language instructors. For depression and anxiety, regression results found that denial coping was a risk factor whereas positive social interaction and classroom climate were protective factors. For hazardous alcohol use, denial coping and higher rank were risk factors and acceptance and time management were protective factors. In terms of academic burnout, in-class and military work hours were risk factors, whereas time management and classroom climate were protective. Finally, lower educational attainment, time spent in the classroom and times spent on military duties predicted exam failure. Individual coping, social connection, and classroom climate are each associated with better DLIFLC student adjustment. Denial coping appears to impede individuals from assembling the personal resources needed to study a foreign language. In contrast, acceptance appears to support healthier adjustment, perhaps freeing individuals to focus on the task at hand rather than expend valuable energy resisting the demands being placed on them. Positive social interaction also appears to provide an important resource for students, and positive classroom climate is also associated with better mental health. These findings suggest that there are measures that individuals and the school can take to improve the DLIFLC experience and support students as they manage a myriad of stressors given the significance of their success to individual students and to the larger organization.

Routine Screening Laboratory Studies for Nonheat Stroke Field Heat Injuries Are Unnecessary: A Retrospective Review.

Heat injuries are common in the military training environment. Base policies often mandate that heat causalities require evaluation at a higher level of care, which comes at significant use of resources. Laboratory studies are often ordered routinely, but their utility is unclear at this time. This project evaluated the use of screening laboratory studies for heat casualties brought to Bayne-Jones Army Community Hospital, Fort Polk, Louisiana. Casualties brought from the field directly to the emergency department (ED) were included. Abnormalities in laboratory study findings, admission/discharge rates, and length of stay were documented. From May through September 2014, 104 casualties were seen in the ED because of heat injury. Laboratory tests were ordered for 101 patients. Of these, 11 patients were admitted to the hospital because of laboratory, history, and/or physical examination abnormalities. Nine were discharged in less than 24 hours. The remaining two were discharged within 48 hours; both had documented altered mental status on arrival to the ED. Laboratory test abnormalities were seen in most of the patients and appeared to have no impact on the decision to admit. Routine laboratory studies appeared to have low clinical utility in this patient population. A more targeted approach based on the history and physical examination may reduce military resource use.

Impact of whey protein supplementation on fitness performance, body composition and injury rates in Army initial entry soldiers

Introduction: We have previously observed a beneficial influence of whey protein supplementation on performance and musculoskeletal injury prevention in an initial military training environment while consuming 2 shakes per day. The purpose of this study was to investigate whether once daily whey protein supplementation affects the response to basic combat training.

Hardly Full Metal Jacket: What We Can Learn From a Military Learning Environment.

Hardly Full Metal Jacket: What We Can Learn From a Military Learning Environment.

Cold Saline Infusion and Reduced Severity of Exertional Heat Illness

The standard of care for initial cooling of a suspected exertional heat illness (EHI) in military training environments is application of ‘ice sheets’ to a casualty. Beginning in 2011 Ft Benning emergency medical services implemented cold (4°C) saline infusion to the pre-hospital transport protocol. PURPOSE: To determine the effects of en-route cold saline infusion on biomarkers of EHI severity and length of hospitalization. METHODS:A retrospective cohort chart review of 290 hospitalized EHI casualties was conducted. Casualties that occurred in 2009-10 (N=153) were the control (CON) group; those in 2011-12 (N=137) received cold saline infusion (CSI) en route to the hospital and were the experimental group. Admission and discharge dates were recorded and length of stay (LOS) was calculated. Biomarkers of organ and tissue damage, including peak creatinine (Cr), creatine kinase (CK), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations were recorded. Data were not normally distributed and were analyzed using the Mann-Whitney-Wilcoxon (MWW) Ranked Sum Test; median and inter-quartile range (IQR) are reported. RESULTS: The 290 cases examined represent ~29% of all EHI at Ft Benning and ~6% of all EHI Army-wide during the study period. There were 284 men and 6 women, age 25±5 years.Table: No title available.CONCLUSIONS: These data suggest that the initiation of cold (4°C) saline infusion while en route to a medical treatment facility results in reduced length of stay and lessened severity, as indicated by significantly lower peak ALT and Cr concentrations. Body core temperature data were not available and the effect of CSI on cooling rate remains to be determined.

The effects of repeated low-level blast exposure on hearing in marines.

Background:The study evaluates a group of Military Service Members specialized in blast explosive training called “Breachers” who are routinely exposed to multiple low-level blasts while teaching breaching at the U.S. Marine Corps in Quantico Virginia. The objective of this study was to determine if there are any acute or long-term auditory changes due to repeated low-level blast exposures used in training. The performance of the instructor group “Breachers” was compared to a control group, “Engineers”.Methods:A total of 11 Breachers and four engineers were evaluated in the study. The participants received comprehensive auditory tests, including pure-tone testing, speech-in-noise (SIN) measures, and central auditory behavioral and objective tests using early and late (P300) auditory evoked potentials over a period of 17 months. They also received shorter assessments immediately following the blast-exposure onsite at Quantico.Results:No acute or longitudinal effects were identified. However, there were some interesting baseline effects found in both groups. Contrary to the expected, the onsite hearing thresholds and distortion product otoacoustic emissions were slightly better at a few frequencies immediately after blast-exposure than measurements obtained with the same equipment weeks to months after each blast-exposure.Conclusions:To date, the current study is the most comprehensive study that evaluates the long-term effects of blast-exposure on hearing. Despite extensive testing to assess changes, the findings of this study suggest that the levels of current exposures used in this military training environment do not seem to have an obvious deleterious effect on hearing.