Nonauditory Injury Threshold for Repeated Intense Freefield Impulse Noise

Dodd, Kenneth T.; Yelverton, John T.; Richmond, Donald R.; Morris, Jennifer R.; Ripple, Gary R.

doi:10.1097/00043764-199003000-00015

Cited by 20 publications

(5 citation statements)

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“…An understanding of the physiological underpinnings of mTBI resulting from blast may yet require more sensitive techniques to elucidate the physiological changes that are responsible for the functional changes (Agoston et al, 2009). Importantly, the physiological and biochemical changes occurring after repeated exposure to BOP in the lung, e.g., lowered pulmonary tolerance (Dodd et al, 1990), could contribute to systemic and CNS pathophysiology, though in our studies we have observed no evidence of overt lung pathology resulting from repeated BOP exposure.…”

Section: Discussioncontrasting

confidence: 54%

Assessment of the Effects of Acute and Repeated Exposure to Blast Overpressure in Rodents: Toward a Greater Understanding of Blast and the Potential Ramifications for Injury in Humans Exposed to Blast

Ahlers¹,

Vasserman-Stokes²,

Shaughness³

et al. 2012

Front. Neur.

121

166

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Mild traumatic brain injury (mTBI) resulting from exposure to improvised explosive devices (IEDs) has fueled a requirement to develop animals models that mirror this condition using exposure to blast overpressure (BOP). En route to developing a model of repeated exposure to BOP we sought to initially characterize the effects of acute BOP exposure in rodents, focusing specifically on the levels of BOP exposure that produced clinical mTBI symptoms. We first measured BOP effects on gross motor function on a balance beam. Separate groups of unanesthetized rats were exposed (in different orientations) to 36.6, 74.5, and 116.7 kPa BOP exposure inside a pneumatically driven shock tube. Results demonstrated that rats exposed to 116.7 kPa demonstrated transient alterations or loss of consciousness indicated by a transient loss of righting and by increased latencies on the balance beam. The 116.7 kPa exposure was the threshold for overt pathology for acute BOP exposure with approximately 30% of rats presenting with evidence of subdural hemorrhage and cortical contusions. All animals exposed to 116.7 kPa BOP manifested evidence of significant pulmonary hemorrhage. Anterograde memory deficits were observed in rats exposed to 74.5 kPa facing the BOP wave and rats exposed to 116.7 kPa in the lateral (side) orientation. We next assessed repeated exposure to either lateral or frontal 36.6 kPa BOP in anesthetized rats, once per day for 12 days. Results showed that repeated exposure in the frontal, but not side, orientation to the BOP wave produced a transitory learning deficit on a Morris water maze task as shown by significantly longer latencies to reach the submerged platform in the second and third blocks of a four block session. Implications of these data are discussed in relation to the manifestation of mTBI in military personnel exposed to IEDs. Finally, we suggest that there are multiple types of long-term brain injury from blast exposure.

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Section: Discussioncontrasting

confidence: 54%

Assessment of the Effects of Acute and Repeated Exposure to Blast Overpressure in Rodents: Toward a Greater Understanding of Blast and the Potential Ramifications for Injury in Humans Exposed to Blast

Ahlers¹,

Vasserman-Stokes²,

Shaughness³

et al. 2012

Front. Neur.

121

166

View full text Add to dashboard Cite

show abstract

“…To a large extent, this data is the basis for the lung injury standards described in Defense Explosives Safety Regulation (DESR) 6055.09 Edition 1. (DESR 2019) 12 . In the limited number of previous studies addressing repeated exposures to BOP, Dodd et al exposed animals up to 100 times with exposure rates ranging from 4–10 exposures per day and developed injury risk curves for laryngeal trauma primarily in the absence of pulmonary trauma 2 .…”

Section: Discussionmentioning

confidence: 99%

Pulmonary injury risk curves and behavioral changes from blast overpressure exposures of varying frequency and intensity in rats

Sajja

Statz

Walker

et al. 2020

Sci Rep

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At present, there are no set guidelines establishing cumulative limits for blast exposure numbers and intensities in military personnel, in combat or training operations. The objective of the current study was to define lung injury, pathology, and associated behavioral changes from primary repeated blast lung injury under appropriate exposure conditions and combinations (i.e. blast overpressure (BOP) intensity and exposure frequency) using an advanced blast simulator. Male Sprague Dawley rats were exposed to BOP frontally and laterally at a pressure range of ~ 8.5–19 psi, for up to 30 daily exposures. The extent of lung injury was identified at 24 h following BOP by assessing the extent of surface hemorrhage/contusion, Hematoxylin and Eosin staining, and behavioral deficits with open field activity. Lung injury was mathematically modeled to define the military standard 1% lung injury threshold. Significant levels of histiocytosis and inflammation were observed in pressures ≥ 10 psi and orientation effects were observed at pressures ≥ 13 psi. Experimental data demonstrated ~ 8.5 psi is the threshold for hemorrhage/contusion, up to 30 exposures. Modeling the data predicted injury risk up to 50 exposures with intensity thresholds at 8 psi for front exposure and 6psi for side exposures, which needs to be validated further.

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“…The distribution of erythrocyte extravasation and other parameters was the primary means of scoring severity and adapted from previous scoring methods. 12,15,19 For example, an erythrocyte extravasation score of 3 meant that the detection of erythrocyte extravasation was widely distributed, albeit often without necessarily showing overt histologic hemorrhage (ie, complete filling of airspaces by erythrocytes). Additionally, we examined the lung for vascular congestion, as it can be frequently misdiagnosed by inexperienced observers as pulmonary hemorrhage and because it has been reported in bat pulmonary barotrauma.…”

Section: Tissue Handling and Scoringmentioning

confidence: 99%

A Forensic Investigation Into the Etiology of Bat Mortality at a Wind Farm: Barotrauma or Traumatic Injury?

et al. 2012

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Migrating bats have increased mortality near moving turbine blades at wind farms. The authors evaluated competing hypotheses of barotrauma and traumatic injury to determine the cause. They first examined the utility of lungs from salvaged bat carcasses for histopathologic diagnosis of barotrauma and studied laboratory mice as a model system. Postmortem time, environmental temperature, and freezing of carcasses all affected the development of vascular congestion, hemorrhage, and edema. These common tissue artifacts mimicked the diagnostic criteria of pulmonary barotrauma; therefore, lung tissues from salvaged bats should not be used for barotrauma diagnosis. The authors next compared wind farm (WF) bats to building collision (BC) bats collected near downtown Chicago buildings. WF bats had an increased incidence in fracture cases and specific bone fractures and had more external lacerations than BC bats. WF bats had additional features of traumatic injury, including diaphragmatic hernia, subcutaneous hemorrhage, and bone marrow emboli. In summary, 73% (190 of 262) of WF bats had lesions consistent with traumatic injury. The authors then examined for ruptured tympana, a sensitive marker of barotrauma in humans. BC bats had only 1 case (2%, 1 of 42), but this was attributed to concurrent cranial fractures, whereas WF bats had a 20% (16 of 81) incidence. When cases with concurrent traumatic injury were excluded, this yielded a small fraction (6%, 5 of 81) of WF bats with lesions possibly consistent with barotrauma etiology. Forensic pathology examination of the data strongly suggests that traumatic injury is the major cause of bat mortality at wind farms and, at best, barotrauma is a minor etiology.

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Nonauditory Injury Threshold for Repeated Intense Freefield Impulse Noise

Cited by 20 publications

References 0 publications

Assessment of the Effects of Acute and Repeated Exposure to Blast Overpressure in Rodents: Toward a Greater Understanding of Blast and the Potential Ramifications for Injury in Humans Exposed to Blast

Assessment of the Effects of Acute and Repeated Exposure to Blast Overpressure in Rodents: Toward a Greater Understanding of Blast and the Potential Ramifications for Injury in Humans Exposed to Blast

Pulmonary injury risk curves and behavioral changes from blast overpressure exposures of varying frequency and intensity in rats

A Forensic Investigation Into the Etiology of Bat Mortality at a Wind Farm: Barotrauma or Traumatic Injury?

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