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Rowland JA, Martindale SL. Considerations for the assessment of blast exposure in service members and veterans. Front Neurol 2024; 15:1383710. [PMID: 38685944 PMCID: PMC11056521 DOI: 10.3389/fneur.2024.1383710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 03/29/2024] [Indexed: 05/02/2024] Open
Abstract
Introduction Blast exposure is an increasingly present occupational hazard for military service members, particularly in modern warfare scenarios. The study of blast exposure in humans is limited by the lack of a consensus definition for blast exposure and considerable variability in measurement. Research has clearly demonstrated a robust and reliable effect of blast exposure on brain structure and function in the absence of other injury mechanisms. However, the exact mechanisms underlying these outcomes remain unclear. Despite clear contributions from preclinical studies, this knowledge has been slow to translate to clinical applications. The present manuscript empirically demonstrates the consequences of variability in measurement and definition across studies through a re-analysis of previously published data from the Chronic Effects of Neurotrauma Study 34. Methods Definitions of blast exposure used in prior work were examined including Blast TBI, Primary Blast TBI, Pressure Severity, Distance, and Frequency of Exposure. Outcomes included both symptom report and cognitive testing. Results Results demonstrate significant differences in outcomes based on the definition of blast exposure used. In some cases the same definition was strongly related to one type of outcome, but unrelated to another. Discussion The implications of these results for the study of blast exposure are discussed and potential actions to address the major limitations in the field are recommended. These include the development of a consensus definition of blast exposure, further refinement of the assessment of blast exposure, continued work to identify relevant mechanisms leading to long-term negative outcomes in humans, and improved education efforts.
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Affiliation(s)
- Jared A. Rowland
- Salisbury VA Healthcare System, Salisbury, NC, United States
- Veterans Integrated Service Network (VISN)-6 Mid-Atlantic Mental Illness, Research Education and Clinical Center (MIRECC), Durham, NC, United States
- Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Sarah L. Martindale
- Salisbury VA Healthcare System, Salisbury, NC, United States
- Veterans Integrated Service Network (VISN)-6 Mid-Atlantic Mental Illness, Research Education and Clinical Center (MIRECC), Durham, NC, United States
- Wake Forest School of Medicine, Winston-Salem, NC, United States
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Wiri S, Massow T, Reid J, Whitty J, Dunbar C, Graves W, Gonzales A, Ortley D, Longwell J, Needham CE, Ziegle A, Phan V, Leonessa F, Duckworth JL. Dynamic monitoring of service members to quantify blast exposure levels during combat training using BlackBox Biometrics Blast Gauges: explosive breaching, shoulder-fired weapons, artillery, mortars, and 0.50 caliber guns. Front Neurol 2023; 14:1175671. [PMID: 37305738 PMCID: PMC10248048 DOI: 10.3389/fneur.2023.1175671] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
CONQUER is a pilot blast monitoring program that monitors, quantifies, and reports to military units the training-related blast overpressure exposure of their service members. Overpressure exposure data are collected using the BlackBox Biometrics (B3) Blast Gauge System (BGS, generation 7) sensors mounted on the body during training. To date, the CONQUER program has recorded 450,000 gauge triggers on monitored service members. The subset of data presented here has been collected from 202 service members undergoing training with explosive breaching charges, shoulder-fired weapons, artillery, mortars, and 0.50 caliber guns. Over 12,000 waveforms were recorded by the sensors worn by these subjects. A maximum peak overpressure of 90.3 kPa (13.1 psi) was recorded during shoulder-fired weapon training. The largest overpressure impulse (a measure of blast energy) was 82.0 kPa-ms (11.9 psi-ms) and it was recorded during explosive breaching with a large wall charge. Operators of 0.50 caliber machine guns have the lowest peak overpressure impulse (as low as 0.62 kPa-ms or 0.09 psi-ms) of the blast sources considered. The data provides information on the accumulation of blast overpressure on service members over an extended period of time. The cumulative peak overpressure, peak overpressure impulse, or timing between exposures is all available in the exposure data.
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Affiliation(s)
- Suthee Wiri
- Applied Research Associates, Albuquerque, NM, United States
| | - Todd Massow
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - James Reid
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Joshua Whitty
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Cyrus Dunbar
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Wallace Graves
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | | | - David Ortley
- Applied Research Associates, Albuquerque, NM, United States
| | | | | | - Alex Ziegle
- Applied Research Associates, Albuquerque, NM, United States
| | - Virginia Phan
- Applied Research Associates, Albuquerque, NM, United States
| | - Fabio Leonessa
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Josh L Duckworth
- Neurology Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Argo Iv TF, Wagner CD, Walilko TJ, Bentley TB. Transfer Function for Relative Blast Overpressure Through Porcine and Human Skulls In Situ. Mil Med 2023; 188:e607-e614. [PMID: 34677614 DOI: 10.1093/milmed/usab412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/08/2021] [Accepted: 09/27/2021] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION The overarching objective of the Office of Naval Research sponsored Blast Load Assessment Sense and Test (BLAST) program was to quantify neurofunctional risk from repeated blast exposure. However, human studies have limitations in data collection that can only be addressed by animal models. To utilize a large animal model in this work, researchers developed an approach for scaling blast exposure data from animal to human-equivalent loading. For this study, energy interacting with the brain tissue was selected as a translation metric because of the hypothesized association between observed neurological changes and energy transmitted through the skull. This article describes the methodology used to derive an energy-based transfer function capable of serving as a global correspondence rule for primary blast injury exposure, allowing researchers to derive human-appropriate thresholds from animal data. METHODS AND MATERIALS To generate data for the development of the transfer functions, three disarticulated cadaveric Yucatan minipigs and three postmortem human surrogate heads were exposed to blast overpressure using a large bore, compressed-gas shock tube. Pressure gauges in the free field, on the skull surface, and pressure probes within the brain cavity filled with Sylgard silicone gel recorded the pressure propagation through the skull of each specimen. The frequency components of the freefield and brain cavity measurements from the pig and human surrogates were interrogated in the frequency domain. Doing so quantifies the differences in the amount of energy, in each frequency band, transmitted through both the porcine and the human skull, and the transfer function was calculated to quantify those differences. RESULTS Nonlinear energy transmission was observed for both the porcine and human skulls, indicating that linear scaling would not be appropriate for developing porcine to human transfer functions. This study demonstrated similar responses between species with little to no attenuation at frequencies below 30 Hz. The phase of the pressure transmission to the brain is also similar for both species up to approximately 10 kHz. There were two notable differences between the porcine and human surrogates. First, in the 40-100 Hz range, human subjects have approximately 8 dB more pressure transmitted through the skull relative to porcine subjects. Second, in the 1-10 kHz range, human subjects have up to 10 dB more pressure transmitted into the brain (10 dB more attenuation) relative to the porcine subjects. CONCLUSIONS The fundamental goal of this study was to develop pig-to-human transfer functions to allow researchers to interpret data collected from large animal studies and aid in deriving risk functions for repeated blast exposures. Similarities in porcine and human brain physiology make the minipig experimental model an excellent candidate for blast research. However, differences in the skull geometry have historically made the interpretation of animal data difficult for the purposes of characterizing potential neurological risk in humans. Human equivalent loading conditions are critical so that the thresholds are not over- or underpredicted due to differences in porcine skull geometry. This research provides a solution to this challenge, providing a robust methodology for interpreting animal data for blast research.
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Roy MJ, Keyser DO, Rowe SS, Hernandez RS, Dovel M, Romero H, Lee D, Menezes M, Magee E, Brooks DJ, Lai C, Gill J, Wiri S, Metzger E, Werner JK, Brungart D, Kulinski DM, Nathan D, Carr WS. Methodology of the INVestigating traIning assoCiated blasT pAthology (INVICTA) study. BMC Med Res Methodol 2022; 22:317. [PMID: 36513998 PMCID: PMC9746108 DOI: 10.1186/s12874-022-01807-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Subconcussive blast exposure during military training has been the subject of both anecdotal concerns and reports in the medical literature, but prior studies have often been small and have used inconsistent methods. METHODS This paper presents the methodology employed in INVestigating traIning assoCiated blasT pAthology (INVICTA) to assess a wide range of aspects of brain function, including immediate and delayed recall, gait and balance, audiologic and oculomotor function, cerebral blood flow, brain electrical activity and neuroimaging and blood biomarkers. RESULTS A number of the methods employed in INVICTA are relatively easy to reproducibly utilize, and can be completed efficiently, while other measures require greater technical expertise, take longer to complete, or may have logistical challenges. CONCLUSIONS This presentation of methods used to assess the impact of blast exposure on the brain is intended to facilitate greater uniformity of data collection in this setting, which would enable comparison between different types of blast exposure and environmental circumstances, as well as to facilitate meta-analyses and syntheses across studies.
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Affiliation(s)
- Michael J. Roy
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA
| | - David O. Keyser
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA
| | - Sheilah S. Rowe
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Rene S. Hernandez
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Marcia Dovel
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Holland Romero
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Diana Lee
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Matthew Menezes
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Elizabeth Magee
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Danielle J. Brooks
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Chen Lai
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Jessica Gill
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.94365.3d0000 0001 2297 5165National Institutes of Health, Bethesda, MD USA
| | - Suthee Wiri
- grid.422775.10000 0004 0477 9461Applied Research Associates, Albuquerque, NM USA
| | - Elizabeth Metzger
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - J. Kent Werner
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA
| | - Douglas Brungart
- grid.414467.40000 0001 0560 6544Walter Reed National Military Medical Center, Bethesda, MD USA
| | - Devon M. Kulinski
- grid.414467.40000 0001 0560 6544Walter Reed National Military Medical Center, Bethesda, MD USA
| | - Dominic Nathan
- grid.265436.00000 0001 0421 5525Department of Medicine, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD 20814 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation, Rockville, MD USA
| | - Walter S. Carr
- grid.507680.c0000 0001 2230 3166Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD USA
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