War Injury. Saman W.Boskani HDD, FIBMS Maxillofacial Surgeon

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1 War Injury Saman W.Boskani HDD, FIBMS Maxillofacial Surgeon

2 War is the only proper school for a surgeon Hippocrates

3 Pathophysiology and Ballistics The management of missile injuries must not be undertaken without clear understanding of the mechanisms of wounding caused both by bullet and fragments However surgeon should treat the wound, not the weapon

4 Projectiles Any material that travels & has the ability to injure, like glass, a falling object, or a bullet. The energy within that projectile is dependent on the velocity, the weight, and distance. Air resistance slows an object, as do barriers Material makes up and design of a projectile can determine how energy is transferred to the target.

5 Ballistics is the science of projectile motion. ; Ballistic science seeks to explain the behavior of the projectile and is typically divided into three stages: 1. Internal (or interior) ballistics describes the forces that apply to a projectile from the time the propellant is ignited to the time the projectile leaves the barrel.

6 2. External ballistics refers to forces that act on the bullet in flight. The primary factors that govern external ballistics are the weight and shape of the bullet. 3. Terminal ballistics is the study of bullet behavior once it impacts the target and is primarily concerned with how much energy is transferred to the target material and the resultant damage. The science of terminal ballistics is most important to the surgeon

7 Ballistics of missile injury relies on several factors, including -kinetic energy -mass -velocity -shape of the projectile and -fragmentation potential Traditionally, kinetic energy has been used as the basis to explain wounds caused by a gunshot. Simple physics can be applied to the projectile using the following formula: KE = ½ mv 2

8 where KE is kinetic energy, m is the mass of the projectile, and V is the velocity of the projectile. Wounding power is typically related to the amount of kinetic energy transferred to the target: P = ½ m (V impact V exit) 2 where P is power, m is mass of the projectile, and V is velocity. Based on these formulas, the velocity of a projectile has traditionally been considered far more important than its mass in wounding power.

9 Missile wounds are classified into : 1- Low energy transfer ( LET ) 2- High energy transfer ( HET ) regarding to velocity gunshots are classified as low velocity (< 350 m/s), medium velocity ( m/s), and high velocity (> 600 m/s). a velocity of approximately. 50 m/s is required to penetrate the skin, and a velocity of around 65 m/s will fracture bone.

10 Low energy transfer wounds For most practical purposes bullets & fragments Striking the body at velocities below that of sound in air (340 m sec -1 ) cause LET wounds like handgun bullet Characteristically : Bruising of tissue around the wound track Temporary cavitations Wounds described as a cutting or laceration

11 High energy transfer wounds Military Rifle bullets have a much higher available energy by virtue of their velocity may have up to 3000 joules of available energy. a HET wounds can be said to have occurred if tow important phenomena are observed ;are 1- propagation of stress wave 2- cavitation

12 The Stress Waves Some times incorrectly described as a shock wave, but it does not have the characteristics or velocity of shock wave produced by an explosion This precede the cavitation phenomena since it moves faster than the speed of sound even in tissue, it is transmitted, particularly well down fluid filled structures such as blood vessels, causing endothelial damage and thrombosis some distant from wound track

13 Because Maximum damage occurs at interfaces of differing acoustic impedance,hence the damage occurs to endothelial cells lining blood vessels. Fracture of bone away from the wound track ; a definite feature of HET wounds is more likely to be due to the stress wave than the cavitation effect Bone fragments with attached periosteum will pulsate in the temporary cavity but those detached may act as a secondary missile

14 cavitation It is a feature of those missile that their velocity is greater than the speed of sound in air, the so called HET wounds. It is described by growth, collapse and damped regrowth of a temporary cavity as an elastic tissue respond to passage of high velocity missile The extent of which damage occurs depends on the amount of the energy transferred and the resilience of the tissue involved.

15 The permanent cavity describes the space that results from direct tissue disruption and destruction. It is a function of the penetration and size of the projectile. It is generally considered to be the most important factor in the wounding and stopping power of a particular cartridge and bullet. The temporary cavity is produced as the projectile travels through the target tissue. Transfer of kinetic energy results in a stretching of elastic tissues. Although they may remain intact, some of these tissues may be irrecoverably damaged.

16 Stress wave

17 The damage extending up to 20 times the diameter of the missile, the effect of such a missile with the confine of skull is devastating

18 firearms and fragments

19 Firearms classified as : Handguns : pistols and revolvers most are low or medium velocity, typically < 600 m/s, and usually cause tissue damage along the bullet tract only. rifles : range from low to high velocities shotguns. Shotguns typically are smooth bore weapons that fire shells filled with lead shot of various sizes.

20 Bullets : A typical Bullet injury is wound with small entrance and large exit wound Rifles and handguns are classified by caliber. The caliber of a weapon is the diameter of the muzzle bore, which is the same as the diameter of the projectile Which is by american syatem is inch and in British system is metric

21 earliest and simplest classification Of GSWs non-penetrating (grazing or blast wound), penetrating (bullet does not exit), Perforating (in and out), and Avulsive ( in & out + tissue loss )

22 Rubber and plastic bullets Use for riot control Administer a painful slap from range of 45 m Severe enough to deter rioter But not severe enough to cause major injury Bullet long, measures 15 cm in length by 3.8 cm in diameter and weights 50 g It is velocity is 73 m/sec

23 Shotgun Wounds Because of their unique ballistic profile, shotgun injuries are often classified based on the distance to the target : type I shotgun injuries (< 5 m), the pellets strike the target as a single mass, resulting in massive kinetic energy transfer, tissue avulsion, and a high mortality rate (85 90%).

24 Type II injuries (5 12 m) usually result in much less tissue destruction. At these distances there is significant dispersal of the pellet sand loss of energy. Penetration may occur through deep fascia, but fractures are rare. Ocular injuries can occur as well as embolization of lead pellets, but mortality is less (15 20%). Type III injury At distances > 12 m, usually only the skin is penetrated and mortality is rare (0 5%).

25 suicidal attempt A characteristic wound profile head position (the patient places the barrel of the weapon in the mouth or under the chin ) Neck hyperextend to reach the trigger Characteristic powder burns are seen at the entrance wound The face frequently takes the full effect of the blast, lethal intracranial involvement is avoided. If a high energy weapon such as a shotgun or rifle is used, the injury can be devastating with significant tissue loss.

26 fragments : Fragment injury may be caused by explosive devices, such as bombs, mortars,shells, rockets, and grenade Mines : are exploding devices which by their design cause traumatic amputation of foot or leg often combined with multiple severe wounds ; which are severely contaminated by mud, grass, piece of shoes, and clothes driven deep into the wound at the time of explosion

27 Blast Injuries: Blast Physics Rapid chemical conversion of a solid or liquid into highly pressurized gases Gases expand rapidly and compress the surrounding air Pressure wave and blast wind are generated and spread in all directions Is affected by the medium through which it travels, i.e., air vs. water

28 Pathophysiology Proposed mechanisms* Spalling Caused by shock wave moving through tissues of different densities molecular disruption Implosion Caused by entrapped gases in hollow organs compressing then expanding visceral disruption

29 Shearing Caused by tissues of different densities moving at different speeds visceral tearing Irreversible Work Caused by forces exceeding the tensile strength of the tissue *Spalling, implosion and shearing are thought to be three mechanisms that cause blast injuries. Irreversible work is currently being researched as a more likely mechanism of injury.

30 Blast Injuries: Categories Primary injury Caused by blast wave over pressure Secondary injury Caused by flying debris shrapnel wounds Tertiary injury Caused by blast wind forceful impact Quaternary injury Caused by other vectors heat, radiation

32 Blast Injuries: Secondary The most common cause of death in a blast event is secondary blast injuries. These injuries are caused by flying debris generated by the explosion. Terrorists often add screws, nails, and other sharp objects to bombs to increase injuries.

33 Mustard gas injury There is no Antidote Supportive therapy & avoidance of secondary infection of both damaged skin ( blistering, pigmentation some times black discoloration) & lung injury Has considerable power of penetration of ordinary clothing and producing severe effects in warm and moist parts of body.

34 Management

35 Aims of war surgery : 1- save life 2- avoid infction complication 3- save limbs 4- minimize residual disability

36 Basic principles of management of war wounds Complete wound excision Delay primary closure (except in face ) Antibiotic Anti-tetanus Vaccine No internal bone fixation

37 Incidence of maxillofacial injury Injuries in warfare and terrorist attack has remained remarkably constant in Head &Neck region About 16% of all injuries in warfare About 21% in terrorist attacks

38 A practical note : Some time the wounds of the face presenting with frightful amount of deformity, but are not generally of so serious nature as their first appearance might lead to un-initiated to expect ; this is due to the face not contain the vital organ and has a high blood supply, this point lead the surgeon an important practical interference that not try to extract all fragments unless comminution be great or completely detached from soft tissue

39 Casualty Sorting Triage which is a French term ;means to sort into groups according to quality It is the process of categorizing patients according to the degree of severity of injury so that priorities can be established in order to use the available facilities most efficiently for the evacuation and care of the wounded. The aim of mass casualty situation is to do the best for the most

40 War wounded should be treated according to ATLS protocol

Greater the mass the greater the energy Double mass = KE Greater the speed the greater the energy Double speed = x increase KE

Greater the mass the greater the energy Double mass = KE Greater the speed the greater the energy Double speed = x increase KE 1 Chapter 18: Penetrating Trauma 2 Introduction to Penetrating Trauma 28,000 Deaths in US annually due to. Mechanisms of penetrating trauma Knives, Arrows, Nails, etc Understanding principles of energy