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

Abstract

We evaluated the acute (up to 24 h) pathophysiological response to primary blast using a rat model and helium driven shock tube. The shock tube generates animal loadings with controlled pure primary blast parameters over a wide range and field-relevant conditions. We studied the biomechanical loading with a set of pressure gauges mounted on the surface of the nose, in the cranial space, and in the thoracic cavity of cadaver rats. Anesthetized rats were exposed to a single blast at precisely controlled five peak overpressures over a wide range (130, 190, 230, 250, and 290 kPa). We observed 0% mortality rates in 130 and 230 kPa groups, and 30%, 24%, and 100% mortality rates in 190, 250, and 290 kPa groups, respectively. The body weight loss was statistically significant in 190 and 250 kPa groups 24 h after exposure. The data analysis showed the magnitude of peak-to-peak amplitude of intracranial pressure (ICP) fluctuations correlates well with mortality rates. The ICP oscillations recorded for 190, 250, and 290 kPa are characterized by higher frequency (10-20 kHz) than in other two groups (7-8 kHz). We noted acute bradycardia and lung hemorrhage in all groups of rats subjected to the blast. We established the onset of both corresponds to 110 kPa peak overpressure. The immunostaining against immunoglobulin G (IgG) of brain sections of rats sacrificed 24-h post-exposure indicated the diffuse blood-brain barrier breakdown in the brain parenchyma. At high blast intensities (peak overpressure of 190 kPa or more), the IgG uptake by neurons was evident, but there was no evidence of neurodegeneration after 24 h post-exposure, as indicated by cupric silver staining. We observed that the acute response as well as mortality is a non-linear function over the peak overpressure and impulse ranges explored in this work.

Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves

“…Moreover, an accurate quantitative characterization of the acceleration mechanism may be necessary for development of protective strategies against bTBI [15]. However, even though numerous blast-related experimental and computational animal studies have been performed [9,10,14,[16][17][18][19][20], the specific contribution of the acceleration mechanism to bTBI remains elusive.…”

Numerical investigation of the effects of shock tube geometry on the propagation of an ideal blast wave profile

“…In Table 1, all the fixed parameters are listed for reference, including the different lengths of structural compo- 8 , and L 9 ), the corresponding radii (R 2 , R 4 , R 6 , and R 7 ), the initial low pressure P 1 in the test section, and the initial high pressure P 4 in the driver section. The fixed total length (L 9 ) and test section radius (R 4 ) of the shock tube may leave limited flexibility for alternate designs, but the present study of BSTs is focused on determining if the production of ideal blast waveforms is feasible with the possible geometrical configurations or not, and the following results will be applicable for other total lengths of shock tubes, because the sizes of the structural components of the shock tube are the major factors.…”

“…Exposure to incident BOP waves is known to damage the hollow gas-filled organs such as ears, lungs, and intestines [1][2][3][4]. Traumatic brain injury and blast-induced neurotrauma upon exposure to blast waves have also been confirmed in animal studies [5][6][7][8][9]. In order to reproduce the ideal blast wave profiles, the proper designs of these studies are appropriate to replicate field conditions in the laboratory.…”

“…In particular, those tubes used to reproduce BOP waves for the study of biological damage are usually designated as biological shock tubes (BSTs) [12], which include compression-driven and blast-driven designs. Compressiondriven shock tubes [2,8,[10][11][12][13]16] avoid the safety concerns related to the storage and handling of high explosives and reduce the cost of test facilities to maintain, but they often fail to accurately represent the Friedlander waveform of freefield blast waves [5,6]. Blast-driven shock tubes [14,15,17] Fig.…”

Blast Loading of Cells

“…Stretchinduced damage, in particular, has been an attractive area of study for TBI, leading to the development of a number of experimental platforms for studying how cells respond to uniaxial, biaxial and equibiaxial strains [6,40]. Figure 4.9 shows a workflow chart for a relatively recent model used to study neuronal cell stretching as a TBI model over a wide range of strain and strain rates [40].…”