Penetrating Trauma Flashcards
Ballistics
• Study of the characteristics of projectiles in motion and effects upon objects impacted
• Aspects of projectile motion
– Trajectory
– Energy dissipation
Path of a Bullet
• Bullet spins as it travels down barrel
– Rifling in barrel
– Allows bullet to travel straight with slight yaw
– Bullet departs barrel, spinning with a slight wobble or yaw
• Weapon forced backward and absorbs energy
– Recoil
Path of a Bullet
• Remainder of energy propels bullet forward at a high rate of speed.
• As bullet strikes object, it slows and energy is transferred to object.
– Law of Conservation of Energy
Trajectory
• The path a projectile follows
• Bullets are pulled down by gravity as the travel through the air
– Causes a curved path
– The faster the bullet the straighter the path
Factors in Energy Dissipation
- Drag
- Cavitation
- Profile
- Stability
- Expansion
- Shape
Energy Dissipation Drag
– Wind resistance
– The faster the bullet travels, the more drag it experiences
Energy Dissipation Cavitation
– The outward motion of tissue due to a projectile’s passage
– Results in temporary cavity and vacuum
– Related to velocity and how quickly it gives up energy
Stability
Location of bullet’s centre of mass affects it stability
Bullet length increases bullet tumbling
– Can reduce the accuracy of the shot
– Reduced by rifling in barrel (spinning)
Yaw
Gyroscopic effect on the center axis of the bullet that reduces tumbling
Tumbling of bullet once it strikes object
– Reduces kinetic energy
– Greater tissue damage
Expansion and Fragmentation
- Results in increased profile
- Mushrooming
- Initial impact forces may result in fragmenting
- Greater tissue damage
Secondary Impacts
Energy exchange also affected by secondary impacts
– Bullet striking other objects can cause yaw and
tumble
Body Armor (Kevlar)
– Transmits energy throughout entire vest resulting in blunt trauma – Increased risk for • Myocardial Contusion • Pulmonary Contusion • Rib Fractures
Handgun ammunition
– Blunt, more resistant to travel through human tissue
– Releases kinetic energy more quickly
Rifle Bullets
– More pointed, cut through tissue more easily
– If the bullet tumbles, may exchange energy more rapidly
Fragmented bullet
– Will give up energy more quickly through erratic pathways
Handgun characteristics
– Small caliber, short barrel, medium‐velocity
– Effective at close range
– Severity of injury based upon organs damaged
Rifle characteristics
– High-velocity, longer barrel, large caliber
– Increased accuracy at far distances
Assault Rifle Characteristics
– Large magazine, semi‐ or full‐automatic
– Similar injury to hunting rifles
– Multiple wounds
Shotgun Characteristics
– Slug or pellets at medium velocity
– 00 (1/3”) to #9 (pin head sized)
– Larger the load, the smaller the number of projectiles
– Deadly at close range
Knives & Arrows Characteristics
– Low-energy & low-velocity
– Damage related to depth and angle of attack
– Movement of the victim can increase damage
– The extent of the damage is ojen difficult to assess
Projectile Injury Process
• Tip impacts tissue
• Tissue pushed forward and to the side
– Tissue collides with adjacent tissue
• Shock wave of pressure forward and lateral
– Moves perpendicular to bullet path
– Rapid compression, crushes and tears tissue
• Cavity forms behind bullet pulling in debris with suction.
Damage Pathway
• Direct Injury
– Damage done as the projectile strikes tissue
• Pressure Shock Wave
– Human tissue is semi‐fluid
– Solid and dense organs are damaged greatly
Damage Pathway
• Temporary Cavity – Due to cavitation • Permanent Cavity – Due to seriously damaged tissue • Zone of Injury – Area that extends beyond the area of permanent injury
Low-Velocity Wounds (Objects)
– Knives, Ice-picks, Arrows
– Flying objects or debris
– Slow speed limits kinetic energy exchange as the object enters the body
Low velocity wounds (Injury limited to tissue impacted)
– Object pathway
– Object may be twisted or moved
– May be inserted at an oblique angle
Human Characteristics (Male Attacker)
– Most ojen strike with forward, outward or crosswise stroke
Human characteristics (Female Attacker)
Strike with an overhand, downward stroke
Human Characteristics (Victim)
– Initially aiempt to sheild themselves with their arms
– Often receive upper extremity lacerations (defensive wounds)
Injuries to Tissue and Organs
• Extent of damage varies by the particular type of tissue that a projectile encounters
• Density of tissue affects the efficiency of energy transmission
• Resiliency:
– Strength and elasticity of an object
Connective tissue
• Dense, elastic and held together very well
• Limited tissue damage
– Characteristically absorbs energy
– Wound track closes quickly due to resilience, limiting prijectile’s pathway
Solid Organs
– Have density but not resiliency
– Tissues compress and stretch in relation to cavittional wave
– Hemorrhage tends to be severe
Hollow Organs
– Filled with noncompressable fluid that rapidly transmits energy
– Energy can tear organ apart explosively
– Slower, smaller projectiles may produce small holes and create slow leaks
Lungs
- Air in lung absorbs energy
- Parenchyma is compressed and rebounds
- Injury less extensive than with other tissue
- Significant disruption of chest wall integrity may result in pneumothorax or hemothorax
Bone
- Densest, most rigid and nonelastic body tissue
- Resists displacement until it fractures often into numerous pieces
- Significantly alter projectile’s path through the body
General Body Regions (Extremities)
– Injury limited to resiliency of tissue
– 60-80% of injuries with
General Body Regions Abdomen (Includes Pelvis)
– Highly susceptible to injury and life-threatening hemorrhage
– May perforate bowel resulting in irritation and infection
General Body Region Thorax
– Rib impact results in explosive energy
– Heart & great vessels have extensive damage due to lack of fluid compression
– Any large chest wound compromises breathing
General Body Region Neck
– Traversed by several critical structures
– Penetrating trauma likely to damage vital
structures:
• Airway compromise
• Heomrrhage
• Neurological deficits
– Associated swelling and hematoma may lead to similar complications
General Body Region Head
– Skull is a hollow strong and rigid container
– Brain is a delicate semisolid organ very susceptible to injury
– If bullet penetrates the skull, cavitational energy trapped, damage extensive
– Suicide attempt often result in facial trauma as a result of weapon recoil
Entrance wound
• Size of bullet profile for non-deforming bullets
• Deforming projectiles may cause large wounds
• Close Range
– Powder Burns (tattoing of powder)
– 1-2 mm circle of discoloration
– Localized subcutaneous emphysema
Exit Wounds
• Caused by the physical damage – Passage of bullet – Cavitational wave • Blown outward appearance • May more accurately reflect damage caused by bullet
Scene Assessment
• Ensure that police have secured the scene before you enter it
– Potential for violence
• Consider the possibility
– Additional assailants
– Victim may be armed
• Preserve crime scenes as much as possible
– Cut around bullet or knife holes and preserve clothing as evidence
Penetrating Wound Assessment
• Determine pathway of object
– Projectiles do not always travel in straight lines
– Look for entrance and exit wounds
• Anticipate potential organ injury
• Bullet wounds to head, chest or abdomen
– Rapid transport
– Treat aggressively for shock
Facial Wounds
• Gunshot wounds may destroy airway landmarks
• May have to consider more invasive procedures
– Cricothyrotomy
– Cricothyrostomy
Chest Wounds
• Chest wall is thick and resilient
• Requires a large wound to create opening for air movement
– Smaller wounds usually result in no air movement
• May have to utilize:
– Three sided dressing or chest seal
– Needle decompression
• Consider the possibility of trauma to the heart and great vessels
Impaled Objects
• Mainly a low velocity wound, dangerous to remove
– May cause more damage on exit
– May be restricting blood loss
• Immobilize as the object is found
• Objects to be removed
– Lodged in cheek or trachea that interfere with airway
– Interfering with CPR
Different projectiles of different weights traveling at different speeds cause:
– Low Energy/Low Velocity • Knives and arrows – Medium Energy/Medium Velocity Weapons • Handguns, shotguns, low-powered rifles • 250-400 mps – High Energy/High Velocity • Assault Rifles • 600-1,000 mps
