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PENETRATING TRAUMA

PENETRATING TRAUMA. OBJECTIVES. Upon completion, the student will be able to: Explain the energy exchange process between a penetrating object or projectile and the object it strikes.

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PENETRATING TRAUMA

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  1. PENETRATING TRAUMA Paramedic Lecture – Penetrating Trauma

  2. OBJECTIVES • Upon completion, the student will be able to: • Explain the energy exchange process between a penetrating object or projectile and the object it strikes. • Determine the effects that profile, yaw, tumble, expansion, and fragmentation have on projectile energy transfer. • Describe elements of the ballistic injury process including direct injury, cavitation, temporary cavity, permanent cavity, and zone of injury. Paramedic Lecture – Penetrating Trauma

  3. OBJECTIVES • Identify the relative effects a penetrating object or projectile has when striking various body regions and tissues. • Anticipate the injury types and the extent of damage associated with high-velocity/high-energy projectiles, such as rifle bullets; with medium-energy/medium-velocity projectiles such as handgun and shotgun bullets, slugs, or pellets; and with low-energy/low-velocity penetrating objects, such as knives and arrows. Paramedic Lecture – Penetrating Trauma

  4. OBJECTIVES • Identify important elements of the scene size-up associated with shootings or stabbings. • Identify and explain any special assessment and care considerations for patients with penetrating trauma. • Given several scenarios for penetrating trauma patients, provide the appropriate scene size-up, initial assessment, rapid trauma or focused physical exam, and history, detailed exam, and ongoing assessment and provide appropriate patient care and transportation. Paramedic Lecture – Penetrating Trauma

  5. INTRODUCTION • 38,000 deaths occur each year as a result of shootings. • Additional mechanisms include: • Knives • Arrows • Nails • Pieces of glass or wire Paramedic Lecture – Penetrating Trauma

  6. INTRODUCTION • Physical laws govern the energy exchange process associated with penetrating trauma. • Types of weapons and projectiles involved and the characteristics of the tissue they impact all affect the severity of injury with penetrating trauma. Paramedic Lecture – Penetrating Trauma

  7. PHYSICS • When a projectile strikes a target, it exchanges its energy of motion, more properly called kinetic energy, with the object struck. Kinetic Energy = Mass (weight) x Velocity (speed)2 2 • Velocity of the projectile accounts for more kinetic energy than mass. Paramedic Lecture – Penetrating Trauma

  8. PHYSICS • Relationship between mass and velocity explains why very small and relatively light bullets traveling very fast have the potential to do great harm. • In other words, speed kills. Paramedic Lecture – Penetrating Trauma

  9. PHYSICSLaw of Conservation of Energy • Explains why the projectile kinetic energy is transformed into damage as it slows. • If a projectile like a bullet remains within the object struck, then all its energy is transferred to the object. Paramedic Lecture – Penetrating Trauma

  10. PHYSICSLaw of Conservation of Energy • If the projectile passes completely through the object, then the energy transferred to the object is equal to the kinetic energy just prior to entry minus the energy remaining in the projectile as it exists. Paramedic Lecture – Penetrating Trauma

  11. Ballistics • Study of the characteristics of projectiles in motion and their effects upon objects they impact is called ballistics. • One aspect of ballistics is trajectory, or the curved path that a bullet follows once fired from a gun. • The faster the bullet, the flatter its curve of travel and the straighter its trajectory. Paramedic Lecture – Penetrating Trauma

  12. Ballistics • More significant aspect of projectile travel is energy dissipation. • Factors that affect energy dissipation include: • Drag • Cavitations • Profile • Stability • Expansion • Shape Paramedic Lecture – Penetrating Trauma

  13. BallisticsDrag • As a bullet travels through the air, it experiences wind resistance, or drag. • The faster it travels, the more drag it experiences and the greater the slowing effects. Paramedic Lecture – Penetrating Trauma

  14. BallisticsDrag • This represents a reduction in bullet speed, it also means, if all else is equal, that the damage caused by a bullet fired at close range will be more severe than from one fired at a distance. Paramedic Lecture – Penetrating Trauma

  15. BallisticsCavitations • Objects traveling relatively slowly, and without much kinetic energy, like knives or arrows, will affect only the tissue they contact. • High- or medium-velocity projectiles, like rifle or handgun bullets, however, set a portion of the semi-fluid body tissue in motion, creating a shock wave and a temporary cavity in the tissue. Paramedic Lecture – Penetrating Trauma

  16. BallisticsCavitations • This stage of the destruction process is known as cavitations and is related to the bullet’s velocity and how quickly it gives up its energy. • Energy exchange rate is related to the size of the projectile’s contacting surface and to its shape. Paramedic Lecture – Penetrating Trauma

  17. BallisticsProfile • The portion of the bullet you would see if you looked at it as it traveled toward you. • Larger this surface profile, the greater the energy exchange rate, the more quickly the bullet slows, and the more extensive the damage to surrounding tissue. Paramedic Lecture – Penetrating Trauma

  18. BallisticsCavitations • Profile is the bullet’s diameter, or caliber. • To increase the energy exchange rate, bullets are designed to become unstable as they pass from one medium to another or to deform through expansion or fragmentation. Paramedic Lecture – Penetrating Trauma

  19. BallisticsStability • The location of a bullet’s center of mass affects its stability both during its flight and when it impacts a solid or semi-solid object. • Longer the bullet, the farther the center of mass is from its lead edge. • If the bullet is deflected from straight flight (barrel exhaust/gust of wind), the lift created by the projectile’s tip passing through air an an angle will cause the bullet to tumble. Paramedic Lecture – Penetrating Trauma

  20. BallisticsStability • Tumbling will slow the bullet and decrease the accuracy of the shot. • Tumbling is prevented by the gun barrel’s rifling, which causes it so spin. • If the spinning bullet is slightly deflected, it will wobble, or yaw, then slowly return to straight flight. Paramedic Lecture – Penetrating Trauma

  21. BallisticsStability • When a bullet impacts a dense substance, several things happen. • If there is already a yaw, the yaw greatly increases as the bullet begins its penetration. • With tumbling, there is a larger presenting profile, the rifle bullet’s kinetic energy exchange rate increases, as does it potential for causing damage. Paramedic Lecture – Penetrating Trauma

  22. Projectiles also may increase their profile and their energy exchange rate by deforming when the strike a medium denser than air. BallisticsExpansion & Fragmentation Paramedic Lecture – Penetrating Trauma

  23. As the bullet’s nose contacts the target, it is compressed by the weight of the rest of the bullet behind it. Nose of the bullet mushrooms outward as the rear of the bullet pushes into it, increasing it’s diameter. BallisticsExpansion & Fragmentation Paramedic Lecture – Penetrating Trauma

  24. In some cases, the initial impact forces are so great that the bullet separates into several pieces or fragments. BallisticsExpansion & Fragmentation Paramedic Lecture – Penetrating Trauma

  25. Increases the energy exchange rate of impact because the total surface area of the fragments is much greater than that of the original bullet profile. BallisticsExpansion & Fragmentation Paramedic Lecture – Penetrating Trauma

  26. BallisticsShape • Some bullets (hollow tips) are specifically designed to mushroom and/or fragment upon impact and thereby increase the damage they cause. • Handgun ammunition is rather blunt, is more resistant to travel through human tissue, and releases kinetic energy more quickly. • Rifle bullets are more pointed and cut through the tissue more efficiently. Paramedic Lecture – Penetrating Trauma

  27. Secondary Impacts • Energy exchange between a projectile and body tissue can also be affected by any object the projectile strikes during its travel. • Deflections could induce a yaw and tumble. • They may also cause bullet deformity, and thereby increase the energy exchange rate. • So called ‘assault’ rifle bullets intentionally have a slight yaw as they travel through the air to cause more damage when they enter the body. Paramedic Lecture – Penetrating Trauma

  28. Secondary Impacts • Special type of secondary impact occurs when the bullet collides with body armor (Kevlar). • Energy is absorbed by the armor and distributed to the victim in much the same way that the recoil of a gun is distributed to the shooter. • May produce blunt trauma in the person hit, not penetrating. Paramedic Lecture – Penetrating Trauma

  29. Secondary Impacts • High-energy projectiles may pass through body armor, but in doing so they dissipate some of their energy as blunt trauma, thereby reducing the penetrating kinetic energy as the bullet strikes body tissue. Paramedic Lecture – Penetrating Trauma

  30. WEAPON CHARACTERISTICS • Include: • Handguns • Domestic rifles • Assault rifles • Shotguns • Knives • Arrows Paramedic Lecture – Penetrating Trauma

  31. Handgun • Often small-caliber, short-barreled, medium-velocity. • Limited accuracy, most effective at close range. • Blunter shape of the bullet. • Associated with mushrooming and fragmentation. • Severity of injury is usually related to the organs directly damaged by the bullet’s passage. Paramedic Lecture – Penetrating Trauma

  32. Rifle • Compared to a handgun bullet, a rifle bullet generally travels much faster. • With longer barrel of the rifle, bullet travels straighter for longer distances. • High-energy rifle bullet travels much farther, with greater accuracy, and retains much more of its kinetic energy than does the handgun projectile. Paramedic Lecture – Penetrating Trauma

  33. Rifle • Due to the rifle bullet’s high speed and energy, it transfers great damaging energy to the target. • Results in extensive wounds with injuries that extend beyond the projectile’s immediate track. Paramedic Lecture – Penetrating Trauma

  34. Shotgun • Can expel a single projectile, or multiple projectiles, at medium velocity. • Limited in range and accuracy. • Injuries sustained at close range can be very severe or lethal. • Generally used as a close quarters weapon. Paramedic Lecture – Penetrating Trauma

  35. Knives & Arrows • Slow-moving, penetrating objects causing low-velocity, low-energy wounds. • Low-velocity objects do not produce either a pressure shock wave or cavitations. • Damage is usually limited to physical injury caused by direct contact between the blade or object and the victim’s tissue. Paramedic Lecture – Penetrating Trauma

  36. Knives & Arrows • Severity of a low-velocity penetrating wound, however, can often be difficult to assess because the depth and angle of the object’s insertion cannot be determined from the victims wound. • In addition, an attacker may move the penetrating object about inside the victim, then leave it in place or withdraw it. Paramedic Lecture – Penetrating Trauma

  37. Damage pathway that a high-velocity projectile inflicts results from three specific factors: Direct Injury Pressure Shock Wave Cavitations DAMAGE PATHWAY Paramedic Lecture – Penetrating Trauma

  38. Damage PathwayDirect Injury • Damage done as the projectile strikes tissue, contuses and tears that tissue, and pushes the tissue out of its way. • Limited to the profile of the bullet as it moves through the body or the profiles or resulting fragments as the bullet breaks apart. • Handgun bullet damage is usually limited to direct injury. Paramedic Lecture – Penetrating Trauma

  39. Damage PathwayPressure Shockwave • A high-velocity, high-energy projectile strikes human flesh, it creates a pressure shock wave. • Impact of the projectile transmits energy outward very quickly. • Tissue cells in front of the bullet are pushed forward and to the side at great speed. Paramedic Lecture – Penetrating Trauma

  40. Damage PathwayPressure Shockwave • They push adjacent cells forward and outward, creating a moving wave of pressure and tissue. • The faster and blunter the bullet, the greater the effect. • Pressure wave travels very well through fluid, such as blood, and may injure blood vessels distant from the wound pathway. Paramedic Lecture – Penetrating Trauma

  41. Damage PathwayPressure Shockwave • Air-filled cavities, such as the alveoli of the lung, compress very easily and absorb the pressure, quickly limiting the shock wave and the resulting temporary cavity. • Solid and dense organs, like the live and spleen, suffer greatly as the pressure wave moves through them, causing internal hemorrhage. Paramedic Lecture – Penetrating Trauma

  42. Damage PathwayTemporary Cavity • A space created behind the high-energy bullet as tissue moves rapidly away from the bullet’s path. • Size of the cavity depends upon the amount of energy transferred during the bullet’s passage. Paramedic Lecture – Penetrating Trauma

  43. Damage PathwayTemporary Cavity • With rifle bullets, the temporary cavity may be as much as 12 times larger than the projectile’s profile. • After the bullet’s passage, tissue elasticity causes the temporary cavity to close. Paramedic Lecture – Penetrating Trauma

  44. Damage PathwayPermanent Cavity • Movement that creates the temporary cavity crushes, stretches, and tears the affected tissues. • Processes seriously damage the area in and adjacent to the bullet’s path and may also damage the tissue’s elasticity. • Tissue thus may not return to its normal orientation. Paramedic Lecture – Penetrating Trauma

  45. Damage PathwayPermanent Cavity • This results in a permanent cavity that in some cases may be larger than the bullet’s diameter. • Not a void but is filled with disrupted tissues, some air, fluid, and debris. Paramedic Lecture – Penetrating Trauma

  46. Damage PathwayZone of Injury • Zone of injury extends beyond the permanent cavity. • Contains contused tissue that does not function normally and may be slow to heal because of cell and tissue damage, disrupted blood flow, and infection. Paramedic Lecture – Penetrating Trauma

  47. Entrance wounds are usually the size of the bullet’s profile. The situation is different, however, with bullets that deform or tumble during flight. Entrance Wound Paramedic Lecture – Penetrating Trauma

  48. Entrance Wound • With these the initial impact can be especially violent, producing a much larger and more disrupted entry wound than the caliber of the bullet alone would suggest. Paramedic Lecture – Penetrating Trauma

  49. Entrance WoundClose Range • Characteristics include: • Elements of the barrel exhaust and bullet passage. • Tattooing from the propellant residue may form a darkened circle or an oval around the entry wound and contaminate the wound itself. • Small ridge of discoloration around the entrance caused by the spinning bullet. Paramedic Lecture – Penetrating Trauma

  50. Entrance WoundClose Range • If barrel is very close or against the skin as the weapon is fired, it may push the barrel exhaust into the wound producing subcutaneous emphysema and crepitus to the touch. • Barrel is held a few inches from the skin, you may notice some burns caused by the hot gases of the barrel exhaust. Paramedic Lecture – Penetrating Trauma

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