Occupational Blast Wave Exposure During Multiday 0.50 Caliber Rifle Course

Skotak, Maciej; LaValle, Christina R.; Misistia, Anthony; Egnoto, Michael J.; Chandra, Namas; Kamimori, Gary H.

doi:10.3389/fneur.2019.00797

Cited by 21 publications

(11 citation statements)

References 16 publications

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“…SRT is similar among concussed vs. non-concussed athletes ( 35 ), and the participants in this study were exposed to subconcussive overpressure conditions. The decrease in PRT and GNG subtasks is indicative of a slightly faster response that has been previously reported to occur among nearly 67% of study participants ( 29 ) and may be reflective of a “practice effect” among persons without a clinically defined concussion ( 36 ). Essentially, the participants are likely paying more attention to the task itself, which is common.…”

Section: Discussionmentioning

confidence: 54%

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Overpressure Exposure From .50-Caliber Rifle Training Is Associated With Increased Amyloid Beta Peptides in Serum

et al. 2020

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Background: Overpressure (OP) is an increase in air pressure above normal atmospheric levels. Military personnel are repeatedly exposed to low levels of OP caused by various weapon systems. Repeated OP may increase risk of neurological disease or psychological disorder diagnoses. A means to detect early phase effects that may be relevant to brain trauma remain elusive. Therefore, development of quantitative and objective OP-mediated effects during acute timeframes would vastly augment point-of-care or field-based decisions. This pilot study evaluated the amplitude of traumatic brain injury (TBI)-associated biomarkers in serum as a consequence of repeated OP exposure from .50-caliber rifle use over training multiple days. Objective: To determine the acute temporal profile of TBI-associated serum biomarkers and their relationship with neurocognitive decrements or self-reported symptoms among participants exposed to low-level, repeated OP from weapons used in a training environment. Methods: Study participants were enrolled in .50-caliber sniper rifle training and exposed to mild OP (peak pressure 3.8-4.5 psi, impulse 19.27-42.22 psi-ms per day) for three consecutive days (D1-D3). Defense automated neurobehavioral assessment (DANA) neurocognitive testing, symptom reporting, and blood collection were conducted 2-3 h before (pre-) and again 0.45-3 h after (post-) OP exposure. The TBI-associated serum biomarkers, glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), neurofilament light (Nf-L), tau, and amyloid beta peptides (Aβ-40 and Aβ-42) were measured using digital ELISAs. Results: Serum GFAP decreased on D1 and D3 but not D2 after OP exposure. Nf-L was suppressed on D3 alone. Aβ-40 was elevated on D2 alone while Aβ-42 was elevated each day after OP exposure. Suppression of GFAP and elevation of Aβ-42 correlated to OP-mediated impulse levels measured on D3. Thangavelu et al. Amyloid Beta Peptides After Overpressure Conclusions: Acute measurement of Aβ-peptides may have utility as biomarkers of subconcussive OP caused by rifle fire. Fluctuation of GFAP, Nf-L, and particularly Aβ peptide levels may have utility as acute, systemic responders of subconcussive OP exposure caused by rifle fire even in the absence of extreme operational deficits or clinically defined concussion.

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Section: Discussionmentioning

confidence: 54%

“…OP measurements were conducted as previously described (29). All participants were exposed to 3-days of OP events, firing 4-50 rounds per day from a variety of positions (prone, seated, kneeling, standing, and supported standing from barricade).…”

Section: Overpressure Measurementsmentioning

confidence: 99%

Overpressure Exposure From .50-Caliber Rifle Training Is Associated With Increased Amyloid Beta Peptides in Serum

et al. 2020

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“…The characteristics of the overpressure dosage (the most critical set include peak overpressure, impulse, and inter-exposure interval, Δt) can be easily obtained from the blast gauges worn by trainees. One successful attempt to extract these vital data is presented in the paper by our group working in collaboration with the Walter Reed Army Institute of Research (WRAIR) team lead by Dr. Kamimori (23). The significance of the availability of this kind of data is paramount: for the first time, it creates an opportunity to develop animal models based on quantified human data.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Review of Experimental Rodent Models of Repeated Blast TBI

et al. 2019

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We reviewed the relevant literature delineating advances in the development of the experimental models of repeated blast TBI (rbTBI). It appears this subject is a relatively unexplored area considering the first work published in 2007 and the bulk of peer-reviewed papers was published post-2011. There are merely 34 papers published to date utilizing rodent rbTBI models. We performed an analysis and extracted basic parameters to capture the characteristics of the exposure conditions (the blast intensity, inter-exposure interval and the number of exposures), the age and weight of the animal models most commonly used in the studies, and their endpoints. Our analysis revealed three strains of rodents are predominantly used: Sprague Dawley and Long Evans rats and wild type (C57BL/6J) mice, and young adult animals 8 to 12-week-old are a preferred choice. Typical exposure conditions are the following: (1) peak overpressure in the 27–145 kPa (4–21 psi) range, (2) number of exposures: 2 (13.9%), 3 (63.9%), 5 (16.7%), or 12 (5.6%) with a single exposure used for a baseline comparison in 41.24% of the studies. Two inter-exposure interval durations were used: (1) short (1–30 min.) and (2) extended (24 h) between consecutive shock wave exposures. The experiments included characterization of repeated blast exposure effects on auditory, ocular and neurological function, with a focus on brain etiology in most of the published work. We present an overview of major histopathological findings, which are supplemented by studies implementing MRI (DTI) and behavioral changes after rbTBI in the acute (1–7 days post-injury), subacute (7–14 days), and chronic (>14 days) phases post-injury.

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“…past [1,21,25,27], while reference reflected pressure was measured by 3 PCB sensors (marked as 29, 30 and 31 in Fig 1B). The representative pressure profiles captured in the incident and reflected pressure configurations by sensors from both manufacturers are presented in Fig 1C-1F.…”

Section: Plos Onementioning

confidence: 99%

“…Military personnel are often exposed to blast overpressure during training with explosives as well as heavy (e.g., mortars, rockets & machine guns) and light (rifles & pistols) weapons and during combat [1,2]. Recent research has demonstrated that exposure to blast overpressure can result in deficits in neurocognitive performance [3,4] and changes in blood biomarkers [5][6][7][8][9] in the absence of a medically diagnosable injury such as concussion.…”

Section: Introductionmentioning

confidence: 99%

Sensor orientation and other factors which increase the blast overpressure reporting errors

et al. 2020

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This study compared the response of the wearable sensors tested against the industry-standard pressure transducers at blast overpressure (BOP) levels typically experienced in training. We systematically evaluated the effects of the sensor orientation with respect to the direction of the incident shock wave and demonstrated how the averaging methods affect the reported pressure values. The evaluated methods included averaging peak overpressure and impulse of all four sensors mounted on a helmet, taking the average of the three sensors, or isolating the incident pressure equivalent using two sensors. The experimental procedures were conducted in controlled laboratory conditions using the shock tube, and some of the findings were verified in field conditions with live fire charges during explosive breaching training. We used four different orientations (0˚, 90˚, 180˚, and 270˚) of the headform retrofitted with commonly fielded helmets (ACH, ECH, Ops-Core) with four B3 Blast Gauge sensors. We determined that averaging the peak overpressure values overestimates the actual dosage experienced by operators, which is caused by the reflected pressure contribution. This conclusion is valid despite the identified limitation of the B3 gauges that consistently underreport the peak reflected overpressure, compared to the industry-standard sensors. We also noted consistent overestimation of the impulse. These findings demonstrate that extreme caution should be exercised when interpreting occupational blast exposure results without knowing the orientation of the sensors. Pure numerical values without the geometrical, training-regime specific information such as the position of the sensors, the distance and orientation of the trainee to the source of the blast wave, and weapon system used will inevitably lead to erroneous estimation of the individual and cumulative blast overpressure (BOP) dosages. Considering that the 4 psi (~28 kPa) incident BOP is currently accepted as the threshold exposure safety value, a misinterpretation of exposure level may lead to an inaccurate estimation of BOP at the minimum standoff distance (MSD), or exclusion criteria.

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Occupational Blast Wave Exposure During Multiday 0.50 Caliber Rifle Course

Cited by 21 publications

References 16 publications

Overpressure Exposure From .50-Caliber Rifle Training Is Associated With Increased Amyloid Beta Peptides in Serum

Overpressure Exposure From .50-Caliber Rifle Training Is Associated With Increased Amyloid Beta Peptides in Serum

A Comprehensive Review of Experimental Rodent Models of Repeated Blast TBI

Sensor orientation and other factors which increase the blast overpressure reporting errors

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