Gunshot Wounds

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Gunshot Wounds Kinematics and Patient Specific Regional Injuries.

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Gunshot Wounds

Transcript of Gunshot Wounds

  • Gunshot WoundsKinematics and Patient Specific Regional Injuries.

  • 30 December 1997,MexicoA security guard intending to impress female friends took a deadly gamble, losing his life in a game of Russian roulette at La Paz fast-food restaurant. Police say Victor, twenty-one, died instantly on Saturday when he put his .38-caliber revolver to his head and pulled the trigger at a suburban hamburger outlet. Reports state that Alba was trying to impress some female friends.Hoy de La Paz, daily newspaper

  • Gunshot Wound StatisticsThe past decade, 1500 Americans have died annually from unintentional gunshot wounds.Unintentional gunshot wounds accounted for 20% of all nonfatal firearm related injuries.It is estimated that for every person who dies from an unintentional gunshot wound each year, almost 13 others are treated in emergency departments for unintentional, nonfatal gunshot wounds. (in Sinauer)

  • KinematicsKinematics is the science of motion. In human movement, it is the study of the positions, angles, velocities, and accelerations of body segments. In gunshot wounds (GSW) we can use this to determine the extent of injury from the forces and motion involved.

  • Injuries Resulting From GSWThere are 3 primary factors that determine the extent of injury in GSW.1. Frontal Area.2. Velocity.3. Distance.

  • Frontal AreaFrontal area is the surface area of the bullet that strikes an object. Factors that increase frontal area are:Profile.Tumble.Fragmentation.

  • ProfileA pointed bullet if crushed & deformed as the result of striking the human body, will have a much larger frontal area than before its shape was changed. A hollow point bullet is a good example of this. It flattens & spreads on impact, striking more tissue, creating a larger cavity & greater injury.

    ProfileProfile

    FrontFrontBullet beforeimpact.Bullet afterimpact.

  • TumbleA bullets center of gravity is located nearer to the base than to the nose of the bullet. When the nose of the bullet strikes an object it slows rapidly. Momentum continues to carry the base of the bullet forward causing an end-over-end motion or tumble.

  • Tumble

    Bullets Center of GravityThere is a greater frontal surface exposed as the missile tumbles & is 90 degreesto the path. More tissue is impacted & therefore, more energy exchange occurs resulting in greater tissue damage.

  • FragmentationBullets with soft noses or vertical cuts increase damage by breaking apart on impact. The mass of fragments produced creates a larger frontal area than a solid bullet and energy is dispersed rapidly into the tissues. A shot gun injury is the ultimate example of fragmentation.

  • VelocityVelocity is a key factor to the overall extent of GSW injuries.According to the kinetic energy equation: (kinetic energy = mass/ 2 x velocity2) Doubling the mass doubles the energy, however doubling the velocity quadruples the energy.Therefore a small-caliber bullet traveling at high speed can produce a more extensive injury than larger caliber bullet traveling at a lower speed.

  • VelocityFirearms are classified according to energy level as either: Medium velocity weapons orHigh velocity weapons.

  • Medium Velocity These weapons are guns that have short barrels,cartridges that contain small amounts of gun powder and muzzle velocities of less than 1500 feet / second. Example: All Hand guns & some rifles.A temporary cavity is always associated with medium velocity weapons. This cavity is usually 3 to 6 times the size of the missiles frontal surface area.

    Scott Richey 2001

  • Medium Velocity Weapons .

    Scott Richey 2001Scott Richey 200122 Caliber Pistol

  • Medium Velocity Weapons .

    Scott Richey 2001Scott Richey 20019 mm Pistol

  • Medium Velocity Weapons .

    Scott Richey 2001Scott Richey 200144 Caliber Pistol

  • High Velocity High velocity weapons include assault and hunting rifles with a muzzle velocity of more than 1500 feet / second. These weapons use larger cartridges. As the amount of gunpowder in the cartridge increases the speed of the bullet increases. These missiles create a permanent track and produce a much larger temporary cavity with the cavity expanding well beyond of the actual bullet track.

  • High Velocity Cartridges

    Scott Richey 200130/30AK-47AR-15

  • High Velocity Weapons

    Scott Richey 200130/30 Hunting Rifle

  • High Velocity

    Scott Richey 2001AK-47 Assault Rifle

  • High Velocity

    Scott Richey 2001AR-15 Assault Rifle

  • DistanceDistance is also important in severity of injury. Air resistance slows the bullet. Therefore increasing the distance decreases the velocity resulting in less kinetic energy. Unfortunately most victims of GSW injuries are from close range.

  • Patient Specific InjuriesThe patient in the case study was shot in the chest (bullet entered right side) and left lower leg, distal to the proximal fibula.

  • Patient Specific Injuries ConsiderationsThorax- Gunshot wounds to the thorax may result in severe injury to the pulmonary & vascular systems.Pulmonary- If the lungs are penetrated by a bullet, the pleura & pulmonary parenchyma are disrupted producing a pneumothorax. On occasion, the pulmonary defect allows air to continue to flow into the thorax that cannot be expelled. The subsequent increase in pressure may eventually cause collapse of the lung creating a tension pneumothorax.

  • Thoracic InjuriesVascular- GSW injuries may result in massive internal & external hemorrhage. For example, if the pulmonary artery or vein, vena cava, or aorta is destroyed, exsanguination may occur rapidly. Other injuries include hemothorax, myocardial rupture, or pericardial tamponade.

  • Extremity TraumaGSWs to the extremities are occasionally life threatening & may result in disability.Any GSW to the extremity should be evaluated for bone injury, motor sensory integrity, & presence of adequate blood flow.Special considerations include vascular injury with bleeding into soft tissues & damage to muscle, bones, & nerves.

  • Extremity TraumaOur patient had extensive trauma to the left lower leg which required immediate amputation. However, there are several scoring systems in place to differentiate patients who would benefit from primary amputation versus those patients for whom salvage of the limb should be attempted.

  • Scoring SystemsMangled Extremity Syndrome Index- Involves point scales for degree of skin, nerve, vascular & bone injury,injury severity, age, concurrent medical conditions & time to vascular repair. (Requires surgical intervention for accurate determination)Predictive Salvage Index- Use with lower extremities, this system assigns points for the level of an injury, degree of bone & muscle injury & interval before arrival in the operating room.Limb Salvage Index- Based on duration of ischemia & severity of injury to artery, bone, muscle, skin, nerve & deep veins.

  • Scoring SystemsMangled Extremity Severity Score (MESS)- System is based on degree of skeletal, soft tissue injury, ischemia, shock & age.Simple to apply.Most of the information is available at the initial evaluation.

  • Mangled Extremity Severity Score (MESS)

    Skeletal/ Soft-tissue Injury

    Low energy (stab, simple fracture, pistol gunshot wound) 1

    Medium energy (open or multiple fractures, dislocation) 2

    High energy (high speed MVA or rifle GSW) 3

    Very high energy (high speed trauma + gross contamination) 4

  • Mangled Extremity Severity Score (MESS)

    Limb Ischemia

    Pulse reduced or absent but perfusion normal 1*

    Pulseless, paresthesias, diminished capillary refill 2

    Cool, paralyzed, insensate, numb 3*

    * Score doubled for ischemia > 6 hours *

  • Mangled Extremity Severity Score (MESS)

    Shock

    Systolic blood pressure > 90 mmHg 0

    Hypotensive transiently 1

    Persistent Hypotension 2

  • Mangled Extremity Severity Score (MESS)

    Age (years)

    < 30 0

    30-50 1

    > 50 2

  • Scoring SystemsAll of the scoring systems are able to identify the majority of patients who require amputation.None of the scoring systems are able to predict functional outcome.None of the predictive scales have been adequately validated. They should only be used as guides in conjunction with the surgeons judgement & experience.

  • ReferenceAmerican College of Surgeons Committee on Trauma: Advance Trauma Life Support Program. Chicago. 1999America Trauma Society. Trauma Facts.Bonanni, F. The Futility of Predictive Scoring of Mangled Lower Extremities. Journal of Trauma. Jan 1993, v 36 p 99-103.Durham, R. Outcome and Utility of Scoring Systems in the Management of the Mangled Extremity. The American Journal of Surgery,Nov 1996 v 172 p 569.Moylan, J. Pulmonary Chest Trauma: Principles of Trauma Surgery, New York 1997.Pons, P. Pre-hospital Advanced Trauma Life Support for Critical Penetrating Wounds to the Thorax and Abdomen. Journal of Trauma, 1985 v 25.Sinauer, N. Unintentional, Nonfatal Firearm-Related Injuries: A Preventable Public Health Burden. JAMA, Jun 12, 1996, v 275, p 1740.

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