Biological Effects of Weak Blast Waves and Safety Limits for Internal Organ Injury in the Human Body

Abstract

One hundred and seventeen adult sheep of both sexes, each weighing 15.2-42.4 kg, were used for this study. The purpose of this study was to investigate the relationship of the physical parameters of the waves to internal organ injury by exposing sheep to weak blast waves in TNT (trinitrotoluene) explosions, biological shock tube, and gun muzzle blasts. The results showed that the organ most sensitive to the TNT explosion was the lungs, whereas the upper respiratory tract was most sensitive to muzzle blast waves. The injury thresholds of overpressure were 29.0, 29.5, and 41.2 kPa for upper respiratory tract, lungs, and gastrointestinal tract respectively at a single exposure. Repeated exposure to 60 blasts reduced the injury threshold of the internal organs. The injury thresholds for upper respiratory tract, lungs, and gastrointestinal tract were 21.0, 18.0, and 40.4 kPa, respectively. The duration of overpressure of weak blast waves was 2.4-4.2 milliseconds, which did not significantly affect the severity of injury. The safety limits of weak blast waves to internal organ injury of human body were as follows: Ps = 37-3Ln.Tc.N/4(Tc.N< or = 1000) and Ps = 20.4(Tc.N > 1000). The results suggest that repeated exposures decrease the injury threshold of the internal organs. The safety limits proposed could protect 90% of the exposed population against internal organ injury caused by weak blast waves.

Rat Injury Model under Controlled Field-Relevant Primary Blast Conditions: Acute Response to a Wide Range of Peak Overpressures

“…6 The primary blast injury is most significant in air-containing organs: ears, 7 lungs, [8][9][10][11] upper respiratory tract, 9 and intestines, 12 thanks to direct coupling of stress waves with these organs. 13 The advent of advanced personal protective equipment diminished these types of injuries, but resulted in a vastly increased number of reports on blast-induced brain trauma.…”

Tightly Coupled Repetitive Blast-Induced Traumatic Brain Injury: Development and Characterization in Mice

“…Repetitive blast exposures in Iraq war veterans with post-concussive symptoms were associated with cerebellar hypometabolism (Peskind et al, 2011). In sheep, repeated blast exposure reduced the threshold of injury to lungs and internal organs (Yang et al, 1996). Using pigs, it has been shown that repetitive occupational levels of blast exposure cause brain injury (Saljo et al, 2008).…”

“…Pre-clinical rat models with single and repetitive blast exposures showed that multiple blast exposure increase the stress levels in the animals (Mazurkiewicz-Kwilecki, 1980). Studies with sheep showed that 60 repeats of 39.5, 130, or 196 kPa blast overpressure (BOP) result in mild, moderate, or severe injury in lungs, respectively indicating that peak overpressure is an important factor in the severity of injury (Yang et al, 1996). Repeated blast exposure can increase the severity or decrease the threshold of bTBI suggesting that there may be a period of vulnerability after initial blast exposure (Saljo et al, 2010(Saljo et al, , 2011.…”

Biomechanical modeling for the response of human thorax to blast waves

“…Figure 8 shows the maximum stress values of lung tissue at different gauge points when the human thorax was subjected to different blast waves in various environments. Characteristic distribution of maximum stress can be described as follows: (1) In every scenario, the maximum stress values measured by monitoring point G1 were lower than those measured by monitoring point G2, and we can clearly understand that the regions of the lung tissue connected with front ribs were protected by front ribs; (2) in every scenario, the maximum stress values measured by monitoring points G3 and G5 were higher than those measured by monitoring point G4, and the stress wave propagated at the back of lung tissue, and the regions of the lung tissue contacted with ribs and vertebrae would generate the phenomenon that the reflection stress wave was superposed on the incident stress wave, where relatively higher stress regions would occur; (3) in the free field, the maxi- (4) when the human thorax was subjected to the same blast wave in various environments, the maximum stress values measured by G1 and G2 varied almost consistently, however, comparing the maximum stress values measured by G3, G4 and G5 in the complex blast environments with those in the free field, we can clearly see that the wall in a complex environment would generate a reflection blast wave, which would strike on the human thorax again and, thus, would lead to relatively higher stress. As a result of characteristic distribution for maximum stress, an ever greater level of lung injury would be caused in the complex environment than in the free field; the front ribs attenuated the lung injury, but the back ribs and vertebrae amplified the lung injury, and the level of lung injury would increase with the intensity of the blast wave.…”

“…These blast waves can impact human bodies, resulting in injury that is not associated with any penetrating or blunt trauma injury [1,2].…”