Gunshot wounds By Dr Mohamed Rahil Ali History

Gunshot wounds By ; Dr. Mohamed Rahil Ali

History The gunpowder was first discovered by Chinese and transmitted to Europe around the thirteenth century It quickly followed by the development of projectile weapons based on its explosive Properties The first recorded use of a cannon was by Edward III against the Scots in 1327 small arms carried by one or two soldiers began appearing in the fourteenth century

Demographics Ø GSWs are the second most source of injury and death , after motor vehicle accidents. Ø The majority of civilian firearm injuries are sustained from handguns (86%), followed by shotguns (8%) and rifles (5%). Ø 40% involved the frontal bone and cranium, 9% involved the orbits, 14% involved the maxilla , 13% involved the mandible, and 24% involved multiple sites. Ø Shotgun injuries most commonly involved the mandible followed by the maxilla and zygoma Then orbits and nasal bones. Ø 36% 0 f patients die following admission. All of the deaths were secondary to injuries to the chest, abdomen, or brain. There is small percentage of deaths associated with isolated facial injuries

Ballistics Ø Ballistics is the science of projectile motion. Ø The potential problems of a wound caused by a projectile can be better anticipated if one has some knowledge of the weapon and projectile type that cause the wound. Ø Ballistic science typically divided into three stages : o o o Internal ballistics External ballistics Terminal ballistics

Internal (or interior) ballistics Ø describes the forces that apply to a projectile from the time the propellant is ignited to the time the projectile leaves the barrel. Ø An important consideration is barrel length , longer barrels (rifles) allow the force of the propellant to act on the projectile longer and generate higher velocities than do shorterbarreled weapons. In addition, a longer barrel serves to stabilize the bullet over longer distances.

Ø Most handguns and rifles have barrels with internal grooves referred to as rifling , This keeps the projectile stable in flight over longer distances

External ballistics Ø refers to forces that act on the bullet in flight. Ø The primary factors that govern external ballistics are the weight and shape of the bullet.

Terminal ballistics Ø is the study of bullet behavior once it impacts the target. Ø The science of termal ballistics is most important to the surgeon and is the most common source of controversy when discussing ballistic wounding.

Velocity of the bullet Extent of deviation (yaw) of the bullet Extent of the cavitation Mass of the bullet Factors which affect the degree of injury Composition and shape of the bullet Drag and retardation Size of the bullet

Velocity and Mass of the bullet Ø kinetic energy has been used as the basis to explain wounds caused by the gunshot KE = mv 2 where KE is kinetic energy , ( m ) is the mass of the projectile, and ( v ) is the velocity of the projectile. Ø Wounding power is typically related to the amount of kinetic energy transferred to the target: P = m(V impact – V exit)2 where P is power, m is mass of the projectile, and V is velocity Ø Based on these formulas, the velocity of a projectile considered more important than its mass in wounding power. q Considering a typically sized projectile velocity of approximately 50 m/s is required to penetrate the skin, and a velocity of around 65 m/s will fracture the bone.

Composition and shape of the bullet Ø earliest projectile was a stone or lead ball. Ø Over time the projectile evolved to the conical-shape. Ø full-metal jacket with exposed lead tips to expand on impact for maximum tissue destruction Ø hollow points handgun bullets evolved to compensate for their low velocity which is difficult to expand in tissue. Ø some bullets are designed to explode when impact.

Extent of deviation of the bullet Ø all projectiles become unstable in flight because of the center of gravity lies behind the center of resistance of the bullet (bullet tip ) Ø yaw ; Oscillation of the bullet around there long axis Ø tumble ; rotation of the bullet around there center. Ø when the projectile encounter a denser substance such as tissue, it will starts tumbling lead to Increase in their profiles causes more tissue wounding because it presents a larger surface area , Increase in the rate of kinetic energy dissipation and Increased probability of fragmentation.

Drag and retardation

Classification of gunshot according to velocity low velocity • ( < 350 m/s ) Intermediate velocity • (350– 600 m/s) high velocity • (> 600 m/s)

Components of projectile wounding: Ø Penetration : a bullet must penetrate to a sufficient depth to cause damage. Ø Permanent cavity : the space that results from direct tissue disruption and destruction. Ø Temporary cavity : results in stretching Of elastic tissues. Ø Fragmentation : missile fragment or secondary fragments such as clothing or bone.

Types of the Missiles Fragments • Primary • Secondary Bullets • Handguns • Rifles • Shotguns

Handguns Ø Also called pistols and revolvers Ø Low or intermediate velocity Ø Characterised by short barrel

Rifles Ø intermediate to high velocity Ø Charectarised by long barrel so the bullet has more time to accelerate

Features of high velocity missile: 1) Temporary cavity : Ø results from stretching Of elastic tissues Ø most tissues has an elastic nature and ability to recover from stretching except some tissues such as brain , liver, spleen Ø damage from temporary cavitation is not so important In the face : air cavities mitigate the effect of cavitation

2) Stress wave : Ø Precedes the cavitation phenomena Ø Not like the shock wave it does not have the characteristic or velocity of the shock wave produced by an explosion Ø Transmitted through fluid filled structures like blood vessels causing endothelial damage and thrombosis Ø Fracture of bone away from the wound tract is due to stress wave rather than cavitation Ø For maxillofacial region : the stress wave is more important than cavitation.

Shotguns Ø low to intermediate velocity Ø The charge from shotgun consist of several hundred lead pellets Ø Because of their unique ballistic profile, shotgun injuries are often classified based on the distance to the target …. .

Type I < 5 m ; the pellets strike the target as a single mass, resulting in massive kinetic energy transfer and tissue avulsion • high mortality rate (85– 90%) • • Type II injuries (5– 12 m) ; • usually result in much less tissue destruction. • there is significant dispersal of the pellets and loss of energy. • Penetration may occur through deep fascia, but fractures are rare. Ocular injuries can occur as well as embolization of lead pellets, • mortality rate (15– 20%) • Type III injuries > 12 m ; • usually only the skin is penetrated • mortality is rare (0– 5%)

Fragments shell , grenade , bomb

Bomb blast injuries : • Burns from the flash of explosion. • Blast wave ( shock wave ) of the explosion • Direct injury • Indirect violence Blast wave of the explosion : 1)positive phase: very high pressure travelling faster than the speed of air last for few milliseconds 2)negative phase : low pressure of longer duration Also the blast wave ( shock wave ) has “ spalling “ effect when pass from one medium to another of less density which cause the medium to spall “fragments “ So the shock wave damage in three ways : • Hydrostatic pressure of the shock ( positive phase ) • Dynamic pressure of the shock which follow the hydrostatic pressure behind it ( negative phase ). • Spalling effect

Type of missile wounds : • Nonpenetrating : grazing or blast wound • Penetrating : low impact velocity , bullet does not exit • Perforating : high velocity , bullet in and out • Avulsive : massive wounds with avulsion and loss of tissues.

Management of gunshot wounds : Immediate management primary survey (A, B, C, D, E ) Secondary survey primary surgery Intermediate phase Diet and feeding Oral hygiene Control of infection Late phase soft tissue and bone reconstruction

airway • Loss of the airway is the most likely cause of death in an isolated GSW to the face • Immediately clear the lumen of the airway • Maintain airway patency by three methods : 1. Gravity 2. Endotaracheal intubation 3. Upper airway bypass

Gravity • Patient placed prone with his forehead suspended so that the tongue and mandible may forwords and any debris , blood, vomit will fall out and thus preventing inhalation • If there is reduction in the level of neurological response , placing the patient in recovery position may be adequate but with repeated suction of the lumen • In nonconscious patient oral airway can be used

Endotaracheal intubation • cuff tube inserted either by oral or nasal route • It is difficult to be placed in patient with missile head and neck injury because patient usually conscious , highly distressed and hypoxic and so not tolerated it

Upper airway bypass Ø Used when other techniques failed Ø Include two procedures ; 1. Cricothyroidotomy 2. tracheostomy

Hemorrhage Control Ø Initial control of hemorrhage in the emergency department center is by direct pressure and packing. Ø Blind clamping should be avoided because of the attendant risk of damage to other structures. Ø Standard methods for epistaxis control such as Foley catheters or specially designed balloon catheters will control most midface bleeding Ø In cases of mandible fractures, temporary reduction of the fracture may be required. Ø Indications for angiography include expanding hematoma and bleeding that persists despite local measures. Ø Lacerations of the internal jugular artery are best controlled with ligation or repair

Primary surgery A)Debridment of the wound : Ø wound should heavily irrigated with normal saline and all foreign bodies removed as it is visible. antiseptic solution such as 1% cetrimide can be used for cleaning the wound. Ø Small completely detached pieces of bone better to be removed Ø all pieces with any viable soft tissue attachment should be conserved B)Management of involved teeth : o Teeth remote to fracture tend to fracture transversely below the gingiva ( in contrast to maxilla ) o all invovled and broken teeth should be removed unless used for fixation and then should be removed after fixation completed because it will be source of infection

C)Reduction and Fixation : Ø Closed reduction Ø Open reduction D)Closure of mucosa and skin Ø Primary suture within 24 hr. give best aesthetic result Ø Delayed wounds or contaminated, managed by packing and delayed suturing Ø In high velocity injury Serial surgical debridement” second-look procedures”, at 24 -to 48 hours intervals which reopen the soft tissue to define additional areas of soft tissue necrosis, drain hematoma or developing fluid collections, and ensure bone integrity. Ø Closure Should be watertightl except in area selected for through –and through drainage Ø Closure of palatal defect may be extremely difficult and in this situation better to be packed.

E)Drainage : Ø All shotgun wounds of the mandible should be drained and it is better to be placed in several places Ø Where ever possible , placed away from suture lines Ø In contaminated comminuted fracture the drain better be (through –and through ) to facilitate irrigation Ø Removal of the drain depend on the amount of discharge on the dressing which should be changed at least once daily Ø In general drain should be removed after progressive shortening within the first 10 postoperative days.

management of Skin loss o if skin loss (< 2 cm) it should be reconstructed by undermining o If more ( > 2 cm ) it managed by : • Dressing to promot epithelialisation • Covered by split skin graft • Transposed flap • Free flap

Contamination Ø The projectiles from firearms are not sterile , The heat generated by the discharge of the propellant as well as the friction between the bullet and barrel is not sufficient to sterilize the bullet. Ø Contamination can occur from the bullet and also from skin flora and foreign bodies (clothing) carried into the wound , and wounds in which the bullet traverses the aerodigestive tract or paranasal sinuses are at particular risk. Ø Prophylactic coverage with broad-spectrum antibiotics, typically a second-generation cephalosporin, and tetanus prophylaxis, should be initiated in all gunshot wounds. Ø Lead toxicity may occure but it is a rare complication

Management of foreign bodies within the tissues Ø Evaluation of the risk of removal Ø Small fragments may not be possible to removed all Ø Larger fragments should be removed if : a. b. c. d. Pain Tendernes Deformity Infection e. brass- or copper-jacketed bullets that are in close proximity to central or major peripheral nerves because of potential neurotoxicity

Penetrating injury of the neck Management strategies for penetrating neck injuries are typically based on the zone(s) Involved Zone I ; from the clavicles to the cricoid cartilage Zone II ; from the cricoid cartilage to the angle of the mandible. Zone III ; from the skull base to the angle of the mandible

Penetrating injury to the neck that need urgent management Signs of tracheal injury signs of vascular injury hoarsenes expanding hematoma stridors neurologic deficit subcutaneous emphysema dysphonia, or hemoptysis

Intermediate care : • Diet and feeding • • Liquid diet Nasogastric tube can be used in extensive injury When there is loss of oral sphenicter saliva shield made of acrylic or silicon can be used gastrostomy if longterm bypass of the oral cavity is necessary • Oral hygiene • • Mouth wash with antiseptic solution (chlorhexidine ) Active irrigation with 4% sodium bicarbonate at least once daily Brashing by soft tooth brush 1% hydrocortisone ointment applied regularly to the lip • Control of infection • • • Prophylactic antibiotic to prevent infection especially meningitis and pulmonary infection Infection of fracture site : controled by intermediate surgery to remove teeth or sequestra with drainage of pus if present and do culture and sensetivety test to advocate the appropreiat antibiotic Early mobilisation and physiotherapy to prevent thrombophlebitis

Secondary or late reconstruction treatment : Ø It is difficult to restore function and appearance in the secondary phase so every effort is made to minimise the residual defect during the initial surgical management Ø delayed reconstruction in gunshot wounds that resulted from suicide attempts

References ; Ø Rowe and williams maxillofacial injurries Ø PETERSON'S PRINCIPLES OF ORAL AND MAXILLOFACIAL SURGERY Second Edition Ø Articles from internet

Stop the bullet , kill the gun

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