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Shock tubes and blast injury modeling
Chinese Journal of Traumatology 18 (2015) 187e193
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H O S T E D BY
Chinese Journal of Traumatology journal homepage: http://www.elsevier.com/locate/CJTEE
Invited review
Shock tubes and blast injury modeling Ya-Lei Ning, Yuan-Guo Zhou* Molecular Biology Center, State Key Laboratory of Trauma, Burns and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing 400042, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 22 December 2014 Received in revised form 3 March 2015 Accepted 2 April 2015 Available online 12 November 2015
Explosive blast injury has become the most prevalent injury in recent military conflicts and terrorist attacks. The magnitude of this kind of polytrauma is complex due to the basic physics of blast and the surrounding environments. Therefore, development of stable, reproducible and controllable animal model using an ideal blast simulation device is the key of blast injury research. The present review addresses the modeling of blast injury and applications of shock tubes. © 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: Blast injury Shock tube Animal model Explosive blast
With the use of improvised explosive devices (IEDs) as tactical weapons in recent military conflicts and terrorist attacks, blast injury has become the most prevalent military injury.1,2 There are also a large number of civilian blast injuries and casualties suffering from explosion in mine, oil and gas field and other industrial accidents. Therefore the blast injuries are an increasing problem in both military and civilian practice. The blast injury is a kind of polytrauma resulting from direct or indirect exposure to an explosion. Explosions are physical, chemical or nuclear reactions that involve the rapid release of considerable amounts of energy. An explosion generates an instantaneous increase in pressure and temperature in the immediate vicinity of the explosion which travels outwards from the source of the explosion promptly through the surrounding medium (i.e. air, water, soil, stone, and steel). The high pressure usually lasts a few milliseconds and is followed by a fall in pressure (negative pressure) or suction of the blast wave. This is the formation of a shock wave.3,4 There are four patterns of blast injury. Primary injuries, also called pure blast injuries, are caused by blast waves such as overpressure waves or negative pressure waves directly, primarily affecting air-containing organs and cavities such as the lung, ear and abdomen. Secondary, quaternary and tertiary injuries are indirect ones caused by the fragments of debris propelled by the explosion, by the acceleration * Corresponding author. Tel.: þ86 23 68757471; fax: þ86 23 68817159. E-mail address: [email protected] (Y.-G. Zhou). Peer review under responsibility of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University.
of the body or part of the body by the blast wind, and by miscellaneous factors including dust, flash burns, hot gases and fires, respectively. The basic physics including peak overpressure and negative pressure, the overpressure duration time, spreading speed and the number of pulse depend on the type and the equivalent of the explosion, the medium in which it explodes, and the degree of focusing due to a confined area or walls. This makes the magnitude of the damage hypervariable.3,5 Thus development of stable, reproducible and controllable animal model is the key of blast injury research. And the key of a successful model is an ideal blastdriven device that simulates shock waves with realistic pressureetime profiles and relevant durations. The present review addresses the modeling of blast injury and applications of shock tubes. 1. Blast injury models Blast injuries to experimental animals were first studied systematically in 1914.6 Blast research has attracted much attention during World War Ⅱ. Since then, blast injury research has been driven by the increasing mortality of conventional weapons and the tremendous blast effects caused by nuclear detonations. The most remarkable work has been done in the United States and Sweden, especially by White and Richmind in Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico and by Clemedson and Jonsson in Swedish Defense Research Agency. Blast injury research in China has been on since the 1950s and been conducted uninterruptedly
http://dx.doi.org/10.1016/j.cjtee.2015.04.005 1008-1275/© 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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since China's the first atomic explosion in 1964. Wang investigated to determine the blast levels required for threshold injuries, severe injuries and mortality from nuclear and highexplosive blast, as well as repeated low-level blasts, and published the world's first monograph on blast injury.7 Various species of animals, from large animals such as dogs, sheep, goats, swine, and monkeys to small animals such as rabbits, rats, mice and guinea pigs, as well as insects such as drosophila were subjected to blast injury research. Besides those living animals, in vitro organs, tissues and cells were also used in blast injury modeling. The charge explosion was the main way to inflict injury in the early studies of blast injury. The biological effects of the blast wave depend on the peak overpressure and the positive phase duration. The simplest form of a blast wave is described as the Friedlander waveform (Fig. 1) when detonation occurs in a free field. At the arrival of the shock-front, the pressure increases effectively instantaneously to a maximum (peak overpressure), from which it falls exponentially to sub-atmospheric levels and returns to the ambient pressure (Fig. 2A). This model has been performed using various types and equivalents of explosive sources and large sets of animals of different species and sizes. However, in practice, a large proportion of explosion occurred in confined spaces such as buildings, vehicles and cabins. Unlike the free-field waveform, waveform in confined spaces does not represent an ideal Friedlander wave, but complex ones because of reflection, diffraction, focus, or interaction with the initial shock wave (Fig. 2B). The blast peak pressure is up to 8 times higher and positive duration time is longer in free field compared with the same charge in a confined space. So explosion in confined space is associated with greater morbidity and mortality.8 Many reports have demonstrated the blast injury modeling performed in those conditions. Animals were lying, standing or hanging up in the structures. The charge was placed in or out of the structure. The biophysics, damage effects and mechanisms were investigated in those researches.9 Underwater explosions generate a huge volume of energetic underwater gaseous bubble and a shockwave which is propagated towards the surrounding water. This is reflected as a negative pressure wave on the water surface, which is disrupted, forming a dome of spall. The initial compression pulse from the explosion transmits through the water. Upon reaching the surface, given the change in mechanical impedance at this interface, it is reflected as a release wave. Given the broadly triangular shape of the pressure history from an explosive, the combination of this release with the later parts of the explosive pulse, can result in a region of tensile
stress in the water, opening a region of low pressure, where cavitation may be seen in the water. The overall effect is that high positive pressures are only seen fleetingly at the surface, away from the surface and the duration of the pressure pulse will be longer, therefore floating on the surface will result in lower injury compared to in vertical treading water. The reflected tension wave interacts with the compressive shock wave and accelerates its decay (Fig. 2C). Therefore underwater blast wave was characterized by high propagation speed, high peak overpressure value, great impulse, however, short duration. Under the same explosion condition, the propagation speed of underwater blast wave is about 4 times higher than that of air blast wave, the peak overpressure value may reach about 200 times higher, and the impulse is 8.48e11.80 times greater than that of air blast wave.10 Animal treading water will therefore experience the integral of pressure over time lower portion of the body. Regions of the body which are deeper in the water are more severely affected by the blast wave. Individuals at risk of immersion blast are therefore safer floating on the surface of the water rather than treading water in an upright position.3 The above experiments have determined thresholds for mortality and injuries, provided fundamental data for effects of blast with waveforms (Friedlander waveform) and dose response curves (the Bowen curves).12e15 These experiments also allowed for realistic models with large animals that are more similar in size to humans. Although these models are closely similar to a real accident from an explosion, it is very difficult to collect accurate experimental parameters and to perform on animals early functional examination on the test field. Outdoor conditions in combination with a mass of animals in a single experiment also leads to decreased controllability, less stability, poorer reproducibility and higher cost and hazard. To overcome the above shortcomings, a device that can stimulate real explosive blast waveforms in a controlled laboratory environment is demanded. The bio-shock tube is the one best developed and most widely used. 2. Blast injury modeling using shock tubes 2.1. Bio-shock tubes Shock tubes have been proven to be a most versatile and resilient tool for the investigation of shock-wave-related problems under a laboratory condition covering a wide variety of fields both in fundamental science and in applied technology. They have been used to study high speed aerodynamics, shock wave characteristics
Fig. 1. (A) A drawing of an ideal Friedlander wave showing the peak pressure, the positive impulse and phase duration, and the negative impulse and phase duration. (B) An actual pressureetime history for an explosive blast in the tube. The up-and-down oscillations are caused by the vibration of the needle gauge. The overlaid smooth curve is a replot of the ideal Friedlander waveform shown in (A).9
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Fig. 2. Pressureetime histories of waves under various simulation conditions. (A) Free-field explosion.10 (B) Confined space explosion.9 (C) Underwater explosion.10,11 (D) Shock tube simulation.
as well as the response of material to blast loading for over a century. They are also used to investigate compressible flow phenomena and gas phase combustion reactions. More recently, shock tubes have been used in biomedical researches to study how biological specimens are affected by blast waves.16 Shock tubes can be divided into large-, medium-, small- and micro-scale ones based on length and inner diameter of the tube; divided into long-, medium- and short-duration time ones based on positive duration time; divided into high-, moderate- and lowpressure ones based on peak overpressure, and divided into compressed air- and explosive-driven ones based on how the simulated blast wave is produced. A compressed air-driven shock tube basically consists of two sections of substantially different pressures, namely driving (high pressure) section and driven (test) section, which are separated by a diaphragm. When the diaphragm ruptured by increasing the pressure difference between the two sections or by puncturing with a mechanical device, the overpressure propagates along the test section, causing a shock wave at the leading edge, followed by a decay in the pressure profile that somewhat approximates a blast wave (Fig. 2D). Because biological tissues are different from common nonbiological materials in their viscoelastic properties, heterogeneity, strength and plasticity, there are some special requirements for bioshock tubes, compared with engineering ones. These tubes are specially or mainly used for bio-studies. They produce a shock wave similar to the explosive wave produced by nuclear or charge explosion, although the rise time and the duration time is longer than that produced by free-field explosion. Animals can be subjected to various degrees of blast injury when they are put in or at the open of the tubes. So the tubes can be used to reproduce ideal animal models for studies on pathogenesis of blast injury and its prevention and treatment.17e21 2.2. Parameters and features of classical bio-shock tubes in the world From the 1950s, shock tubes used in laboratory were developed in Sweden and the United States.19,22,23 The shock tube constructed
by Clemedson at the Swedish Defence Research Establishment in the 1950s may be one of the oldest systems that are still in use. It was composed of a 400 mm-wide cylindrical cast iron tube, with a cone shaped tip where a charge of plastic explosives (pentaerythritol tetranitrate) was placed (Fig. 3). Clemedson et al published a number of studies on the effects of blasts on different tissues including vascular and respiratory systems,22,23 central nervous system24 and the cerebral vasculature.25 This is equipment that is used in laboratory environments with the benefit of both a fairly high level of control of the physics in the blast wave and the animal physiology. One limitation is the short duration and very simple form of the blast wave. Compressed-air systems have already used in the 1950s.27 The US aeroamphibious forces have built various types of shock tube. Among those tubes, the large conical shock tube created in the US Naval Weapons Laboratory is the biggest one, with a diameter of 0.4 m in cone tip and 7.2 m in conical bottom and a full length of 736.4 m. From the late 1950s, Richmond et al20,21 spent 11 years and successfully developed 5 types of large- and medium-scale shock tubes with a diameter of 0.31e1.83 m, and systemically studied the wounding or lethal effects of blast wave on different animals under conditions of various peak values and durations. They further applied their results to human beings. The most prominent feature of these devices is that almost all tube sections are available of combinations by various tubes with appropriate diameters, thus producing various waveforms of different shapes and duration times. In 1987, Jaffin et al28 designed a microgenerator of shock wave. The volume of the driving section was 150 mL with maximum pressure of 10e25 MPa. One or several thick aluminum discs (0.36 mm) were used as diaphragm, which was ruptured by natural inflation. A small animal experiment could be done using this equipment. The pulse duration of this type of tube is usually longer and the peak pressure is much lower than that in the Clemedson tube. One advantage is the absence of quaternary blast effects as well as other disadvantages of explosives. So this type of shock tube is especially good for the study of primary blast injury. However, the shock waves generated by the shock tube are quite different from real
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Fig. 3. Diagram and photograph of the blast tube that was constructed by Clemedson in Sweden in the 1950s. This system may be one of the oldest systems that still are in use.26
shock wave. One major drawback is the lack of a typical negative pressure wave, or short duration time of negative pressure, which is no more than two times the duration time of positive pressure. In practice, a free-field explosion generates a shock wave with a long duration time of negative pressure (3e10 times longer than overpressure duration time). During the 1980s, a set of more applicable bio-shock tubes (BST, large-, medium- and small-scale tubes, Fig. 4) were successfully developed in the Institute of Surgery, Third Military Medical University under guidance of Academician Wang and in cooperation with Institute of Mechanics, Chinese Academy of Sciences.29e31 The system is compressed gas-driven that can simulate overpressure waves of fireworks to 6 tons of TNT explosion and positive duration time of artillery launch to 10 kiloton nuclear explosion. More importantly, negative pressure could be simulated by this system. The BST-I (large-scale) bio-shock tube is 39.34 m long, consisting of 1) a driving section which is 1.59 m long and 0.348 m wide; 2) a double-clamping diaphragm section which is 1.41 m long; 3) a conical section that is 1 m long with inner diameter of 3.348 to 1 m; 4) a transitional section that is 10 m long with inner diameter of 1 m; 5) a test section that is 14 m long; 6) a wave-elimination section with 11 m long; and 7) auxiliary equipment such as air compressor, high-pressure air tank, etc. The maximum overpressure in the driving section can reach 10.3 MPa. In the openended condition, its maximum overpressure was 219 kPa with a duration of 32.7 ms, and maximum negative pressure was 8.4 kPa with a duration of 90 ms. In the close-ended condition, its maximum overpressure went up to 630.3 kPa with a duration of 24.5 ms, and maximum negative pressure wave reached 76 kPa with a duration of 60 ms. This large-scale shock tube could simulate the explosive wave produced by air explosion of tens to 6 tons of TNT. The advantages of this tube are as follows: 1) It adopts a new working principle, that is, as the diaphragm ruptured, the reflected rarefactive wave induced by the cover of driving section catch up with the shock wave, the pressure of shock wave is then
decreased rapidly, forming an exponential wave that is similar to a real explosive blast wave. When the pressure behind rarefactive wave is lower than atmospheric pressure, a negative pressure occurs. Therefore, the tube could simulate an explosive wave characterized with positive, dynamic and negative pressures. 2) The length and the intra-pressure of the driving section could be well regulated by means of a movable diaphragm, thus changes the peak pressures and their duration time, making the experimental parameters highly controllable. 3) Use of the diaphragms made of pure aluminum and double membrane gradient pressurization can accurately regulate the pressure value required to rupture the diaphragm and ensure the stability of driving pressure and reproducibility of the flow field parameters, and also prevent animals from fragment wound in the rupture of the diaphragm. 4) The conical section of the tube is far away from test section, making it possible to get exponential waves of various temperature and duration time in the transitional section under the same driving pressure, thus reducing the requirement of the diaphragm's thickness. 5) A movable baffle plate located at the end of the test section, making it suitable for mimicking the explosion wounding conditions in both open air or in the confined space. Among the above advantages, the most highlighted one is that the pressure decay starts from the peak and that the decay is long enough to get a negative pressure wave of considerable long duration time. Till now such blast wave cannot be simulated elsewhere. The BST-II (medium-scale) bio-shock tube is a polyfunctional modular tube with the length of 34.5 m. The length of the driving section is changeable by means of series connection, forming 12 types in length, which enhances the capacity and range of the tube to simulate explosive wave. The length of the driving section is adjustable (from 0.5 to 0.8 m long) with the inner diameter of 77 mm and maximum overpressure of 22 MPa. There are 5 types of assemblies of the test section, of which the inner diameters are 77, 100, 200, 350 and 600 mm respectively. Therefore the tube can be used to simulate the explosive wave produced at the plateau,
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Fig. 4. Schematic drawing of BST shock tubes. (A) BST-I model: (1) Driving section; (2) Double-clamping diaphragm section; (3) Conical section; (4) Transition section; (5) Test section; (6) Wave elimination section. (B) BST-II model: (1) Driving section; (2) Double-clamping diaphragm section; (3) Test section. (C) BST-III model: (1) Driving section; (2) Clamping diaphragm; (3) Test section; (4) Testing rabbit; (5) Universal-tube support.29 (D) The diagram of the BST-Ⅰshock tube.
underwater, explosive decompression, and impact effects of highvelocity airflow, and so on. The overpressure values and duration time are 2.52e650 kPa and 0.2e2000 ms, respectively. The BST-Ⅲ (small-scale) bio-shock tube is 0.5 m long with a maximum endured overpressure of 68.6 MPa. The test section is designed to have 9 types with inner diameter of 2e10 mm. The peak overpressure and duration time are 26.8e477 kPa and 0.062e16.8 ms, respectively. The volume or pressure in the driving section can be regulated by steel filters, thus enhancing the capability of the tube to produce different intensities of explosive wave. It is used to produce punctuate explosive wave and allows exposure to explosive wave at a fixed distance, region and direction. The advantages of this type of tube are simulation of a typical exponential waveform, long duration time of negative pressure, a negative pressure/overpressure duration time ratio similar to the actual blast wave and a wide range of peak overpressure, peak negative pressure and duration times. Since the development of the set of bio-shock tubes, over 2000 animals, including rats, mice, rabbits, guinea pigs, dogs and sheep, have been subjected to blast injury researches systemically or locally (such as ears, eyes, head, chest and abdomen). This set of tubes could inflict blast injury of various degrees from mild injury of the acoustic organs to immediate death.29,32
2.3. Modern shock tubes Well-documented modern shock tubes can be found at the Walter Reed institute9 and the US Naval Medical Research Center.33,34 The former one is a large-scale blast tube which is 70 feet long and divided into three sections. The proximal end consists of the heavy-walled driver chamber in which explosives are placed. Its dimensions are 8 feet in length and 34 inches in diameter. The middle segment is a 10-foot expansion section that is connected to the test section (Fig. 5). One sophisticated shock tube system has been installed at the Applied Physics Laboratory at Johns Hopkins University.15 This is a modular, multi-chamber shock tube capable of reproducing complex shock wave signatures. The instrumentation allows direct measurement and calculation of the various shock loading characteristics, including static pressure, total pressure, and overpressure impulse.5 2.4. Advantages and disadvantages of shock tubes in blast injury research The biological effects of shock waves produced by shock tubes are similar to that produced by charge or nuclear explosion. Performing blast injury model using the shock tubes has following
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Fig. 5. (A) The diagram of the blast tube in the Walter Reed institute, including the driver, expansion cone, and conduction segments of the blast tube. (B) Photograph of the blast tube.9
advantages: 1) may simulate shock waves with long duration time economically and reproducibly, which is the basic requirement of large-sample statistics of biological experiments. 2) The testing and recording apparatus, such as electrophysiolograph, sensors and radiographic equipment, etc, may approach the shock tube, making instant or early dynamic and functional measurement possible, which is difficult to perform in the explosive test spot. 3) The shock waveform parameters are changeable by means of changing the shock tube assembling and the shape of wave forms is modifiable through some appropriate means. 4) The levels of injury in animals are consistent and the intra-assay and inter-assay of the results are tiny. 5) The experiments may be performed indoors or near the laboratory, avoiding long-distance run around, saving manpower and the cost. Moreover, the experimental procedures and results are not influenced by climatic conditions. However there are some disadvantages. Firstly, shock waves produced by shock tubes lack harmonics existing in explosive blast waves, which may affect the severity of the injuries. Secondly, under the same explosive condition, many factors, such as terrain, climate, personnel protection and posture, may affect the waveform parameters and the level of injuries. A limited number of shock tubes are difficult to simulate all of these conditions. There are also limitations to simulate shock wave under special circumstances such as trenches, cabin, underwater, etc. Furthermore, the shock tube is a permanent equipment. The ability of a single shock tube to simulate shock waves is limited. In order to meet the basic experimental requirement, a series of shock tubes, along with highpressure gas supply and other supporting systems, are demanded, making it difficult for common laboratories to perform the experiment. It often takes several years from design, manufacture, installation, commissioning to put into use.
3. Summary and prospect Although waveform, pressure value and effect of a shock wave simulated by a shock tube is not perfectly consistent with an ideal free-field blast wave, the shock tube has been improved to be a convenient equipment used in laboratory environments with the benefit of both a fairly high controllability and reproducibility of the physics in the blast wave and the animal physiology. Recently, with the development of personal protective equipment, explosive blast-induced torso damage and mortality is greatly reduced, while blast-induced traumatic brain injury has become the most prevalent military injury and described as the “signature injury” of the current military operations.35e37 It has been demonstrated that even mild to moderate blast injury that does not cause serious immediate visible neurological deficits leads to long-term neuropsychiatric abnormalities such as cognitive deficits, posttraumatic stress disorder, etc, which has attracted increased concerns.11,38,39 Therefore there is a need to develop additional appropriate simulating systems according to the needs and characteristics of different experiments. The investigation of molecular and cellular mechanisms may help understanding the blast injury detailedly.
Acknowledgments We gratefully appreciate Academician Wang ZG for critically reading and editing the manuscript. This work was supported by the grants from National Natural Science Foundation of China (No. 81201461), Key Project of Medicine and Health of PLA (No. 08G098) and the Natural Science Foundation of Chongqing, China (No. CSTC2012jjA10107).
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References 1. Tümer N, Svetlov S, Whidden M, et al. Overpressure blast-wave induced brain injury elevates oxidative stress in the hypothalamus and catecholamine biosynthesis in the rat adrenal medulla. Neurosci Lett. 2013;544: 62e67. 2. Walcott BP, Kahle KT. Blast-related traumatic brain injury in U.S. military personnel. N Engl J Med. 2011;365:859e861. 3. Horrocks CL. Blast injuries: biophysics, pathophysiology and management principles. J R Army Med Corps. 2001;147:28e40. 4. Wightman JM, Gladish SL. Explosions and blast injuries. Ann Emerg Med. 2001;37:664e678. 5. Risling M, Davidsson J. Experimental animal models for studies on the mechanisms of blast-induced neurotrauma. Front Neurol. 2012;3:30. 6. Bellamy RF, Zajtchuk R. The Textbook of Military Medicine-conventional Warfare, Ballistic, Blast and Burn Injuries. Washington, DC: Office of the Surgeon General, Department of the Army; 1991. 7. Wang ZG. Blast Injury. Beijing: People's Military Medical Press; 1983. 8. Chaloner E. Blast injury in enclosed spaces. BMJ. 2005;331:119e120. 9. Bauman RA, Ling G, Tong L, et al. An introductory characterization of a combatcasualty-care relevant swine model of closed head injury resulting from exposure to explosive blast. J Neurotrauma. 2009;26:841e860. 10. Ning X, Li XY, Yang ZH, et al. A comparative study on the propagation speed and physical parameters of underwater blast wave and air blast wave. Med J Chin PLA. 2004;29:97e99. 11. Ning YL, Yang N, Chen X, et al. Adenosine A2A receptor deficiency alleviates blast-induced cognitive dysfunction. J Cereb Blood Flow Metab. 2013;33: 1789e1798. 12. White CS, Bowen IG, Richmond DR. Biological tolerance to air blast and related biomedical criteria. CEX-65.4 CEX Rep Civ Eff Exerc. 1965:1e239. 13. Richmond DR, Damon EG, Bowen IG, et al. Air-blast studies with eight species of mammals. Techn Progr Rep DASA 1854. Fission Prod Inhal Proj. 1967: 1e44. 14. Axelsson H, Yelverton JT. Chest wall velocity as a predictor of nonauditory blast injury in a complex wave environment. J Trauma. 1996;40:S31eS37. 15. Cernak I, Merkle AC, Koliatsos VE, et al. The pathobiology of blast injuries and blast-induced neurotrauma as identified using a new experimental model of injury in mice. Neurobiol Dis. 2011;41:538e551. 16. Cernak I. The importance of systemic response in the pathobiology of blastinduced neurotrauma. Front Neurol. 2010;1:151. 17. Merritt AH. Present status of periodontia as a specialty. J Periodontol. 1950;21: 38e40. 18. Klosa J. Synthetic spasmolytics. V Arch Pharm Ber Dtsch Pharm Ges. 1953;23: 104e108. 19. Celander H, Clemedson CJ, Ericsson UA, et al. A study on the relation between the duration of a shock wave and the severity of the blast injury produced by it. Acta Physiol Scand. 1955;33:14e18.
193
20. Richmond DR, Clare VR, Goldizen VC, et al. Biological effects of overpressures of 400 milliseconds duration and its employment in biomedical experiments. Aerosp Med. 1961;32:997e1008. 21. Richmond DR, Goldizen VC, Clare VR, et al. The biologic response to overpressure. III. Mortality in small animals exposed in a shock tube to sharprising overpressures of 3 to 4 msec duration. Aerosp Med. 1962;33:1e27. 22. Clemedson CJ, Hultman H, Gronberg B. Respiration and pulmonary gas exchange in blast injury. J Appl Physiol. 1953;6:213e220. 23. Clemedson CJ, Hultman HI. Air embolism and the cause of death in blast injury. Mil Surg. 1954;114:424e437. 24. Clemedson CJ. Shock wave transmission to the central nervous system. Acta Physiol Scand. 1956;37:204e214. 25. Clemedson CJ, Hartelius H, Holmberg G. The effect of high explosive blast on the cerebral vascular permeability. Acta Pathol Microbiol Scand. 1957;40:89e95. 26. Clemedson CJ, Criborn CO. A detonation chamber for physiological blast research. J Aviat Med. 1955;26:373e381. 27. Celander H, Clemedson CJ, Ericsson UA, et al. The use of a compressed air operated shock tube for physiological blast research. Acta Physiol Scand. 1955;33:6e13. 28. Jaffin JH, McKinney L, Kinney RC, et al. A laboratory model for studying blast overpressure injury. J Trauma. 1987;27:349e356. 29. Wang Z, Sun L, Yang Z, et al. Development of serial bio-shock tubes and their application. Chin Med J Engl. 1998;111:109e113. 30. Wang Z, Sun L, Yang Z, et al. The design production and application of a series of bio-shock tubes. Explos Shock Waves. 1993;13:77e83. 31. Wang Z, Leng H, Yang Z, et al. Introduction of the first bio-tube for experment in China. Acta Acad Med Mil Tertiae. 1989;11:289e290. 32. Tang C, Yang Z, Wang Z, et al. An experimental study on the effects of a biological shock tube. Acta Acad Med Mil Tertiae. 1989;11:172e174. 33. Chavko M, Koller WA, Prusaczyk WK, et al. Measurement of blast wave by a miniature fiber optic pressure transducer in the rat brain. J Neurosci Methods. 2007;159:277e281. 34. Chavko M, Watanabe T, Adeeb S, et al. Relationship between orientation to a blast and pressure wave propagation inside the rat brain. J Neurosci Methods. 2011;195:61e66. 35. Sayer NA. Traumatic brain injury and its neuropsychiatric sequelae in war veterans. Annu Rev Med. 2012;63:405e419. 36. Arun P, Abu-Taleb R, Oguntayo S, et al. Acute mitochondrial dysfunction after blast exposure: potential role of mitochondrial glutamate oxaloacetate transaminase. J Neurotrauma. 2013;30:1645e1651. 37. Cernak I, Noble-Haeusslein LJ. Traumatic brain injury: an overview of pathobiology with emphasis on military populations. J Cereb Blood Flow Metab. 2010;30:255e266. 38. Miller G. Neuropathology. Blast injuries linked to neurodegeneration in veterans. Science. 2012;336:790e791. 39. Goldstein LE, Fisher AM, Tagge CA, et al. Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model. Sci Transl Med. 2012;4:134e160.
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H O S T E D BY
Chinese Journal of Traumatology journal homepage: http://www.elsevier.com/locate/CJTEE
Invited review
Shock tubes and blast injury modeling Ya-Lei Ning, Yuan-Guo Zhou* Molecular Biology Center, State Key Laboratory of Trauma, Burns and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing 400042, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 22 December 2014 Received in revised form 3 March 2015 Accepted 2 April 2015 Available online 12 November 2015
Explosive blast injury has become the most prevalent injury in recent military conflicts and terrorist attacks. The magnitude of this kind of polytrauma is complex due to the basic physics of blast and the surrounding environments. Therefore, development of stable, reproducible and controllable animal model using an ideal blast simulation device is the key of blast injury research. The present review addresses the modeling of blast injury and applications of shock tubes. © 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords: Blast injury Shock tube Animal model Explosive blast
With the use of improvised explosive devices (IEDs) as tactical weapons in recent military conflicts and terrorist attacks, blast injury has become the most prevalent military injury.1,2 There are also a large number of civilian blast injuries and casualties suffering from explosion in mine, oil and gas field and other industrial accidents. Therefore the blast injuries are an increasing problem in both military and civilian practice. The blast injury is a kind of polytrauma resulting from direct or indirect exposure to an explosion. Explosions are physical, chemical or nuclear reactions that involve the rapid release of considerable amounts of energy. An explosion generates an instantaneous increase in pressure and temperature in the immediate vicinity of the explosion which travels outwards from the source of the explosion promptly through the surrounding medium (i.e. air, water, soil, stone, and steel). The high pressure usually lasts a few milliseconds and is followed by a fall in pressure (negative pressure) or suction of the blast wave. This is the formation of a shock wave.3,4 There are four patterns of blast injury. Primary injuries, also called pure blast injuries, are caused by blast waves such as overpressure waves or negative pressure waves directly, primarily affecting air-containing organs and cavities such as the lung, ear and abdomen. Secondary, quaternary and tertiary injuries are indirect ones caused by the fragments of debris propelled by the explosion, by the acceleration * Corresponding author. Tel.: þ86 23 68757471; fax: þ86 23 68817159. E-mail address: [email protected] (Y.-G. Zhou). Peer review under responsibility of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University.
of the body or part of the body by the blast wind, and by miscellaneous factors including dust, flash burns, hot gases and fires, respectively. The basic physics including peak overpressure and negative pressure, the overpressure duration time, spreading speed and the number of pulse depend on the type and the equivalent of the explosion, the medium in which it explodes, and the degree of focusing due to a confined area or walls. This makes the magnitude of the damage hypervariable.3,5 Thus development of stable, reproducible and controllable animal model is the key of blast injury research. And the key of a successful model is an ideal blastdriven device that simulates shock waves with realistic pressureetime profiles and relevant durations. The present review addresses the modeling of blast injury and applications of shock tubes. 1. Blast injury models Blast injuries to experimental animals were first studied systematically in 1914.6 Blast research has attracted much attention during World War Ⅱ. Since then, blast injury research has been driven by the increasing mortality of conventional weapons and the tremendous blast effects caused by nuclear detonations. The most remarkable work has been done in the United States and Sweden, especially by White and Richmind in Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico and by Clemedson and Jonsson in Swedish Defense Research Agency. Blast injury research in China has been on since the 1950s and been conducted uninterruptedly
http://dx.doi.org/10.1016/j.cjtee.2015.04.005 1008-1275/© 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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since China's the first atomic explosion in 1964. Wang investigated to determine the blast levels required for threshold injuries, severe injuries and mortality from nuclear and highexplosive blast, as well as repeated low-level blasts, and published the world's first monograph on blast injury.7 Various species of animals, from large animals such as dogs, sheep, goats, swine, and monkeys to small animals such as rabbits, rats, mice and guinea pigs, as well as insects such as drosophila were subjected to blast injury research. Besides those living animals, in vitro organs, tissues and cells were also used in blast injury modeling. The charge explosion was the main way to inflict injury in the early studies of blast injury. The biological effects of the blast wave depend on the peak overpressure and the positive phase duration. The simplest form of a blast wave is described as the Friedlander waveform (Fig. 1) when detonation occurs in a free field. At the arrival of the shock-front, the pressure increases effectively instantaneously to a maximum (peak overpressure), from which it falls exponentially to sub-atmospheric levels and returns to the ambient pressure (Fig. 2A). This model has been performed using various types and equivalents of explosive sources and large sets of animals of different species and sizes. However, in practice, a large proportion of explosion occurred in confined spaces such as buildings, vehicles and cabins. Unlike the free-field waveform, waveform in confined spaces does not represent an ideal Friedlander wave, but complex ones because of reflection, diffraction, focus, or interaction with the initial shock wave (Fig. 2B). The blast peak pressure is up to 8 times higher and positive duration time is longer in free field compared with the same charge in a confined space. So explosion in confined space is associated with greater morbidity and mortality.8 Many reports have demonstrated the blast injury modeling performed in those conditions. Animals were lying, standing or hanging up in the structures. The charge was placed in or out of the structure. The biophysics, damage effects and mechanisms were investigated in those researches.9 Underwater explosions generate a huge volume of energetic underwater gaseous bubble and a shockwave which is propagated towards the surrounding water. This is reflected as a negative pressure wave on the water surface, which is disrupted, forming a dome of spall. The initial compression pulse from the explosion transmits through the water. Upon reaching the surface, given the change in mechanical impedance at this interface, it is reflected as a release wave. Given the broadly triangular shape of the pressure history from an explosive, the combination of this release with the later parts of the explosive pulse, can result in a region of tensile
stress in the water, opening a region of low pressure, where cavitation may be seen in the water. The overall effect is that high positive pressures are only seen fleetingly at the surface, away from the surface and the duration of the pressure pulse will be longer, therefore floating on the surface will result in lower injury compared to in vertical treading water. The reflected tension wave interacts with the compressive shock wave and accelerates its decay (Fig. 2C). Therefore underwater blast wave was characterized by high propagation speed, high peak overpressure value, great impulse, however, short duration. Under the same explosion condition, the propagation speed of underwater blast wave is about 4 times higher than that of air blast wave, the peak overpressure value may reach about 200 times higher, and the impulse is 8.48e11.80 times greater than that of air blast wave.10 Animal treading water will therefore experience the integral of pressure over time lower portion of the body. Regions of the body which are deeper in the water are more severely affected by the blast wave. Individuals at risk of immersion blast are therefore safer floating on the surface of the water rather than treading water in an upright position.3 The above experiments have determined thresholds for mortality and injuries, provided fundamental data for effects of blast with waveforms (Friedlander waveform) and dose response curves (the Bowen curves).12e15 These experiments also allowed for realistic models with large animals that are more similar in size to humans. Although these models are closely similar to a real accident from an explosion, it is very difficult to collect accurate experimental parameters and to perform on animals early functional examination on the test field. Outdoor conditions in combination with a mass of animals in a single experiment also leads to decreased controllability, less stability, poorer reproducibility and higher cost and hazard. To overcome the above shortcomings, a device that can stimulate real explosive blast waveforms in a controlled laboratory environment is demanded. The bio-shock tube is the one best developed and most widely used. 2. Blast injury modeling using shock tubes 2.1. Bio-shock tubes Shock tubes have been proven to be a most versatile and resilient tool for the investigation of shock-wave-related problems under a laboratory condition covering a wide variety of fields both in fundamental science and in applied technology. They have been used to study high speed aerodynamics, shock wave characteristics
Fig. 1. (A) A drawing of an ideal Friedlander wave showing the peak pressure, the positive impulse and phase duration, and the negative impulse and phase duration. (B) An actual pressureetime history for an explosive blast in the tube. The up-and-down oscillations are caused by the vibration of the needle gauge. The overlaid smooth curve is a replot of the ideal Friedlander waveform shown in (A).9
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Fig. 2. Pressureetime histories of waves under various simulation conditions. (A) Free-field explosion.10 (B) Confined space explosion.9 (C) Underwater explosion.10,11 (D) Shock tube simulation.
as well as the response of material to blast loading for over a century. They are also used to investigate compressible flow phenomena and gas phase combustion reactions. More recently, shock tubes have been used in biomedical researches to study how biological specimens are affected by blast waves.16 Shock tubes can be divided into large-, medium-, small- and micro-scale ones based on length and inner diameter of the tube; divided into long-, medium- and short-duration time ones based on positive duration time; divided into high-, moderate- and lowpressure ones based on peak overpressure, and divided into compressed air- and explosive-driven ones based on how the simulated blast wave is produced. A compressed air-driven shock tube basically consists of two sections of substantially different pressures, namely driving (high pressure) section and driven (test) section, which are separated by a diaphragm. When the diaphragm ruptured by increasing the pressure difference between the two sections or by puncturing with a mechanical device, the overpressure propagates along the test section, causing a shock wave at the leading edge, followed by a decay in the pressure profile that somewhat approximates a blast wave (Fig. 2D). Because biological tissues are different from common nonbiological materials in their viscoelastic properties, heterogeneity, strength and plasticity, there are some special requirements for bioshock tubes, compared with engineering ones. These tubes are specially or mainly used for bio-studies. They produce a shock wave similar to the explosive wave produced by nuclear or charge explosion, although the rise time and the duration time is longer than that produced by free-field explosion. Animals can be subjected to various degrees of blast injury when they are put in or at the open of the tubes. So the tubes can be used to reproduce ideal animal models for studies on pathogenesis of blast injury and its prevention and treatment.17e21 2.2. Parameters and features of classical bio-shock tubes in the world From the 1950s, shock tubes used in laboratory were developed in Sweden and the United States.19,22,23 The shock tube constructed
by Clemedson at the Swedish Defence Research Establishment in the 1950s may be one of the oldest systems that are still in use. It was composed of a 400 mm-wide cylindrical cast iron tube, with a cone shaped tip where a charge of plastic explosives (pentaerythritol tetranitrate) was placed (Fig. 3). Clemedson et al published a number of studies on the effects of blasts on different tissues including vascular and respiratory systems,22,23 central nervous system24 and the cerebral vasculature.25 This is equipment that is used in laboratory environments with the benefit of both a fairly high level of control of the physics in the blast wave and the animal physiology. One limitation is the short duration and very simple form of the blast wave. Compressed-air systems have already used in the 1950s.27 The US aeroamphibious forces have built various types of shock tube. Among those tubes, the large conical shock tube created in the US Naval Weapons Laboratory is the biggest one, with a diameter of 0.4 m in cone tip and 7.2 m in conical bottom and a full length of 736.4 m. From the late 1950s, Richmond et al20,21 spent 11 years and successfully developed 5 types of large- and medium-scale shock tubes with a diameter of 0.31e1.83 m, and systemically studied the wounding or lethal effects of blast wave on different animals under conditions of various peak values and durations. They further applied their results to human beings. The most prominent feature of these devices is that almost all tube sections are available of combinations by various tubes with appropriate diameters, thus producing various waveforms of different shapes and duration times. In 1987, Jaffin et al28 designed a microgenerator of shock wave. The volume of the driving section was 150 mL with maximum pressure of 10e25 MPa. One or several thick aluminum discs (0.36 mm) were used as diaphragm, which was ruptured by natural inflation. A small animal experiment could be done using this equipment. The pulse duration of this type of tube is usually longer and the peak pressure is much lower than that in the Clemedson tube. One advantage is the absence of quaternary blast effects as well as other disadvantages of explosives. So this type of shock tube is especially good for the study of primary blast injury. However, the shock waves generated by the shock tube are quite different from real
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Fig. 3. Diagram and photograph of the blast tube that was constructed by Clemedson in Sweden in the 1950s. This system may be one of the oldest systems that still are in use.26
shock wave. One major drawback is the lack of a typical negative pressure wave, or short duration time of negative pressure, which is no more than two times the duration time of positive pressure. In practice, a free-field explosion generates a shock wave with a long duration time of negative pressure (3e10 times longer than overpressure duration time). During the 1980s, a set of more applicable bio-shock tubes (BST, large-, medium- and small-scale tubes, Fig. 4) were successfully developed in the Institute of Surgery, Third Military Medical University under guidance of Academician Wang and in cooperation with Institute of Mechanics, Chinese Academy of Sciences.29e31 The system is compressed gas-driven that can simulate overpressure waves of fireworks to 6 tons of TNT explosion and positive duration time of artillery launch to 10 kiloton nuclear explosion. More importantly, negative pressure could be simulated by this system. The BST-I (large-scale) bio-shock tube is 39.34 m long, consisting of 1) a driving section which is 1.59 m long and 0.348 m wide; 2) a double-clamping diaphragm section which is 1.41 m long; 3) a conical section that is 1 m long with inner diameter of 3.348 to 1 m; 4) a transitional section that is 10 m long with inner diameter of 1 m; 5) a test section that is 14 m long; 6) a wave-elimination section with 11 m long; and 7) auxiliary equipment such as air compressor, high-pressure air tank, etc. The maximum overpressure in the driving section can reach 10.3 MPa. In the openended condition, its maximum overpressure was 219 kPa with a duration of 32.7 ms, and maximum negative pressure was 8.4 kPa with a duration of 90 ms. In the close-ended condition, its maximum overpressure went up to 630.3 kPa with a duration of 24.5 ms, and maximum negative pressure wave reached 76 kPa with a duration of 60 ms. This large-scale shock tube could simulate the explosive wave produced by air explosion of tens to 6 tons of TNT. The advantages of this tube are as follows: 1) It adopts a new working principle, that is, as the diaphragm ruptured, the reflected rarefactive wave induced by the cover of driving section catch up with the shock wave, the pressure of shock wave is then
decreased rapidly, forming an exponential wave that is similar to a real explosive blast wave. When the pressure behind rarefactive wave is lower than atmospheric pressure, a negative pressure occurs. Therefore, the tube could simulate an explosive wave characterized with positive, dynamic and negative pressures. 2) The length and the intra-pressure of the driving section could be well regulated by means of a movable diaphragm, thus changes the peak pressures and their duration time, making the experimental parameters highly controllable. 3) Use of the diaphragms made of pure aluminum and double membrane gradient pressurization can accurately regulate the pressure value required to rupture the diaphragm and ensure the stability of driving pressure and reproducibility of the flow field parameters, and also prevent animals from fragment wound in the rupture of the diaphragm. 4) The conical section of the tube is far away from test section, making it possible to get exponential waves of various temperature and duration time in the transitional section under the same driving pressure, thus reducing the requirement of the diaphragm's thickness. 5) A movable baffle plate located at the end of the test section, making it suitable for mimicking the explosion wounding conditions in both open air or in the confined space. Among the above advantages, the most highlighted one is that the pressure decay starts from the peak and that the decay is long enough to get a negative pressure wave of considerable long duration time. Till now such blast wave cannot be simulated elsewhere. The BST-II (medium-scale) bio-shock tube is a polyfunctional modular tube with the length of 34.5 m. The length of the driving section is changeable by means of series connection, forming 12 types in length, which enhances the capacity and range of the tube to simulate explosive wave. The length of the driving section is adjustable (from 0.5 to 0.8 m long) with the inner diameter of 77 mm and maximum overpressure of 22 MPa. There are 5 types of assemblies of the test section, of which the inner diameters are 77, 100, 200, 350 and 600 mm respectively. Therefore the tube can be used to simulate the explosive wave produced at the plateau,
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Fig. 4. Schematic drawing of BST shock tubes. (A) BST-I model: (1) Driving section; (2) Double-clamping diaphragm section; (3) Conical section; (4) Transition section; (5) Test section; (6) Wave elimination section. (B) BST-II model: (1) Driving section; (2) Double-clamping diaphragm section; (3) Test section. (C) BST-III model: (1) Driving section; (2) Clamping diaphragm; (3) Test section; (4) Testing rabbit; (5) Universal-tube support.29 (D) The diagram of the BST-Ⅰshock tube.
underwater, explosive decompression, and impact effects of highvelocity airflow, and so on. The overpressure values and duration time are 2.52e650 kPa and 0.2e2000 ms, respectively. The BST-Ⅲ (small-scale) bio-shock tube is 0.5 m long with a maximum endured overpressure of 68.6 MPa. The test section is designed to have 9 types with inner diameter of 2e10 mm. The peak overpressure and duration time are 26.8e477 kPa and 0.062e16.8 ms, respectively. The volume or pressure in the driving section can be regulated by steel filters, thus enhancing the capability of the tube to produce different intensities of explosive wave. It is used to produce punctuate explosive wave and allows exposure to explosive wave at a fixed distance, region and direction. The advantages of this type of tube are simulation of a typical exponential waveform, long duration time of negative pressure, a negative pressure/overpressure duration time ratio similar to the actual blast wave and a wide range of peak overpressure, peak negative pressure and duration times. Since the development of the set of bio-shock tubes, over 2000 animals, including rats, mice, rabbits, guinea pigs, dogs and sheep, have been subjected to blast injury researches systemically or locally (such as ears, eyes, head, chest and abdomen). This set of tubes could inflict blast injury of various degrees from mild injury of the acoustic organs to immediate death.29,32
2.3. Modern shock tubes Well-documented modern shock tubes can be found at the Walter Reed institute9 and the US Naval Medical Research Center.33,34 The former one is a large-scale blast tube which is 70 feet long and divided into three sections. The proximal end consists of the heavy-walled driver chamber in which explosives are placed. Its dimensions are 8 feet in length and 34 inches in diameter. The middle segment is a 10-foot expansion section that is connected to the test section (Fig. 5). One sophisticated shock tube system has been installed at the Applied Physics Laboratory at Johns Hopkins University.15 This is a modular, multi-chamber shock tube capable of reproducing complex shock wave signatures. The instrumentation allows direct measurement and calculation of the various shock loading characteristics, including static pressure, total pressure, and overpressure impulse.5 2.4. Advantages and disadvantages of shock tubes in blast injury research The biological effects of shock waves produced by shock tubes are similar to that produced by charge or nuclear explosion. Performing blast injury model using the shock tubes has following
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Fig. 5. (A) The diagram of the blast tube in the Walter Reed institute, including the driver, expansion cone, and conduction segments of the blast tube. (B) Photograph of the blast tube.9
advantages: 1) may simulate shock waves with long duration time economically and reproducibly, which is the basic requirement of large-sample statistics of biological experiments. 2) The testing and recording apparatus, such as electrophysiolograph, sensors and radiographic equipment, etc, may approach the shock tube, making instant or early dynamic and functional measurement possible, which is difficult to perform in the explosive test spot. 3) The shock waveform parameters are changeable by means of changing the shock tube assembling and the shape of wave forms is modifiable through some appropriate means. 4) The levels of injury in animals are consistent and the intra-assay and inter-assay of the results are tiny. 5) The experiments may be performed indoors or near the laboratory, avoiding long-distance run around, saving manpower and the cost. Moreover, the experimental procedures and results are not influenced by climatic conditions. However there are some disadvantages. Firstly, shock waves produced by shock tubes lack harmonics existing in explosive blast waves, which may affect the severity of the injuries. Secondly, under the same explosive condition, many factors, such as terrain, climate, personnel protection and posture, may affect the waveform parameters and the level of injuries. A limited number of shock tubes are difficult to simulate all of these conditions. There are also limitations to simulate shock wave under special circumstances such as trenches, cabin, underwater, etc. Furthermore, the shock tube is a permanent equipment. The ability of a single shock tube to simulate shock waves is limited. In order to meet the basic experimental requirement, a series of shock tubes, along with highpressure gas supply and other supporting systems, are demanded, making it difficult for common laboratories to perform the experiment. It often takes several years from design, manufacture, installation, commissioning to put into use.
3. Summary and prospect Although waveform, pressure value and effect of a shock wave simulated by a shock tube is not perfectly consistent with an ideal free-field blast wave, the shock tube has been improved to be a convenient equipment used in laboratory environments with the benefit of both a fairly high controllability and reproducibility of the physics in the blast wave and the animal physiology. Recently, with the development of personal protective equipment, explosive blast-induced torso damage and mortality is greatly reduced, while blast-induced traumatic brain injury has become the most prevalent military injury and described as the “signature injury” of the current military operations.35e37 It has been demonstrated that even mild to moderate blast injury that does not cause serious immediate visible neurological deficits leads to long-term neuropsychiatric abnormalities such as cognitive deficits, posttraumatic stress disorder, etc, which has attracted increased concerns.11,38,39 Therefore there is a need to develop additional appropriate simulating systems according to the needs and characteristics of different experiments. The investigation of molecular and cellular mechanisms may help understanding the blast injury detailedly.
Acknowledgments We gratefully appreciate Academician Wang ZG for critically reading and editing the manuscript. This work was supported by the grants from National Natural Science Foundation of China (No. 81201461), Key Project of Medicine and Health of PLA (No. 08G098) and the Natural Science Foundation of Chongqing, China (No. CSTC2012jjA10107).
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References 1. Tümer N, Svetlov S, Whidden M, et al. Overpressure blast-wave induced brain injury elevates oxidative stress in the hypothalamus and catecholamine biosynthesis in the rat adrenal medulla. Neurosci Lett. 2013;544: 62e67. 2. Walcott BP, Kahle KT. Blast-related traumatic brain injury in U.S. military personnel. N Engl J Med. 2011;365:859e861. 3. Horrocks CL. Blast injuries: biophysics, pathophysiology and management principles. J R Army Med Corps. 2001;147:28e40. 4. Wightman JM, Gladish SL. Explosions and blast injuries. Ann Emerg Med. 2001;37:664e678. 5. Risling M, Davidsson J. Experimental animal models for studies on the mechanisms of blast-induced neurotrauma. Front Neurol. 2012;3:30. 6. Bellamy RF, Zajtchuk R. The Textbook of Military Medicine-conventional Warfare, Ballistic, Blast and Burn Injuries. Washington, DC: Office of the Surgeon General, Department of the Army; 1991. 7. Wang ZG. Blast Injury. Beijing: People's Military Medical Press; 1983. 8. Chaloner E. Blast injury in enclosed spaces. BMJ. 2005;331:119e120. 9. Bauman RA, Ling G, Tong L, et al. An introductory characterization of a combatcasualty-care relevant swine model of closed head injury resulting from exposure to explosive blast. J Neurotrauma. 2009;26:841e860. 10. Ning X, Li XY, Yang ZH, et al. A comparative study on the propagation speed and physical parameters of underwater blast wave and air blast wave. Med J Chin PLA. 2004;29:97e99. 11. Ning YL, Yang N, Chen X, et al. Adenosine A2A receptor deficiency alleviates blast-induced cognitive dysfunction. J Cereb Blood Flow Metab. 2013;33: 1789e1798. 12. White CS, Bowen IG, Richmond DR. Biological tolerance to air blast and related biomedical criteria. CEX-65.4 CEX Rep Civ Eff Exerc. 1965:1e239. 13. Richmond DR, Damon EG, Bowen IG, et al. Air-blast studies with eight species of mammals. Techn Progr Rep DASA 1854. Fission Prod Inhal Proj. 1967: 1e44. 14. Axelsson H, Yelverton JT. Chest wall velocity as a predictor of nonauditory blast injury in a complex wave environment. J Trauma. 1996;40:S31eS37. 15. Cernak I, Merkle AC, Koliatsos VE, et al. The pathobiology of blast injuries and blast-induced neurotrauma as identified using a new experimental model of injury in mice. Neurobiol Dis. 2011;41:538e551. 16. Cernak I. The importance of systemic response in the pathobiology of blastinduced neurotrauma. Front Neurol. 2010;1:151. 17. Merritt AH. Present status of periodontia as a specialty. J Periodontol. 1950;21: 38e40. 18. Klosa J. Synthetic spasmolytics. V Arch Pharm Ber Dtsch Pharm Ges. 1953;23: 104e108. 19. Celander H, Clemedson CJ, Ericsson UA, et al. A study on the relation between the duration of a shock wave and the severity of the blast injury produced by it. Acta Physiol Scand. 1955;33:14e18.
193
20. Richmond DR, Clare VR, Goldizen VC, et al. Biological effects of overpressures of 400 milliseconds duration and its employment in biomedical experiments. Aerosp Med. 1961;32:997e1008. 21. Richmond DR, Goldizen VC, Clare VR, et al. The biologic response to overpressure. III. Mortality in small animals exposed in a shock tube to sharprising overpressures of 3 to 4 msec duration. Aerosp Med. 1962;33:1e27. 22. Clemedson CJ, Hultman H, Gronberg B. Respiration and pulmonary gas exchange in blast injury. J Appl Physiol. 1953;6:213e220. 23. Clemedson CJ, Hultman HI. Air embolism and the cause of death in blast injury. Mil Surg. 1954;114:424e437. 24. Clemedson CJ. Shock wave transmission to the central nervous system. Acta Physiol Scand. 1956;37:204e214. 25. Clemedson CJ, Hartelius H, Holmberg G. The effect of high explosive blast on the cerebral vascular permeability. Acta Pathol Microbiol Scand. 1957;40:89e95. 26. Clemedson CJ, Criborn CO. A detonation chamber for physiological blast research. J Aviat Med. 1955;26:373e381. 27. Celander H, Clemedson CJ, Ericsson UA, et al. The use of a compressed air operated shock tube for physiological blast research. Acta Physiol Scand. 1955;33:6e13. 28. Jaffin JH, McKinney L, Kinney RC, et al. A laboratory model for studying blast overpressure injury. J Trauma. 1987;27:349e356. 29. Wang Z, Sun L, Yang Z, et al. Development of serial bio-shock tubes and their application. Chin Med J Engl. 1998;111:109e113. 30. Wang Z, Sun L, Yang Z, et al. The design production and application of a series of bio-shock tubes. Explos Shock Waves. 1993;13:77e83. 31. Wang Z, Leng H, Yang Z, et al. Introduction of the first bio-tube for experment in China. Acta Acad Med Mil Tertiae. 1989;11:289e290. 32. Tang C, Yang Z, Wang Z, et al. An experimental study on the effects of a biological shock tube. Acta Acad Med Mil Tertiae. 1989;11:172e174. 33. Chavko M, Koller WA, Prusaczyk WK, et al. Measurement of blast wave by a miniature fiber optic pressure transducer in the rat brain. J Neurosci Methods. 2007;159:277e281. 34. Chavko M, Watanabe T, Adeeb S, et al. Relationship between orientation to a blast and pressure wave propagation inside the rat brain. J Neurosci Methods. 2011;195:61e66. 35. Sayer NA. Traumatic brain injury and its neuropsychiatric sequelae in war veterans. Annu Rev Med. 2012;63:405e419. 36. Arun P, Abu-Taleb R, Oguntayo S, et al. Acute mitochondrial dysfunction after blast exposure: potential role of mitochondrial glutamate oxaloacetate transaminase. J Neurotrauma. 2013;30:1645e1651. 37. Cernak I, Noble-Haeusslein LJ. Traumatic brain injury: an overview of pathobiology with emphasis on military populations. J Cereb Blood Flow Metab. 2010;30:255e266. 38. Miller G. Neuropathology. Blast injuries linked to neurodegeneration in veterans. Science. 2012;336:790e791. 39. Goldstein LE, Fisher AM, Tagge CA, et al. Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model. Sci Transl Med. 2012;4:134e160.