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Paramedic Care:Principles & Practice
Volume 5Trauma Emergencies
Chapter 3 Penetrating Trauma
TopicsIntroduction to Penetrating TraumaKinetics of Penetrating TraumaSpecific Tissue/Organ InjuriesSpecial Concerns with Penetrating Trauma
Introduction to Penetrating Trauma
Introduction to Penetrating Trauma
There are 30,000 deaths in the U.S. annually due to shootings.Other mechanisms of penetrating trauma include:
Knives, arrows, nails, etc.
Understanding the principles of energy exchange increases the index of suspicion associated with the MOI.
Kinetics of Penetrating Trauma
Kinetics of Penetrating TraumaWhen a projectile strikes a target, it exchanges its kinetic energy with the object struck. An object’s kinetic energy is equal to its mass times the square of its velocity, all divided by 2.
Kinetics of Penetrating TraumaThe greater the mass of an object, the greater its energy.
If you double the mass of an object, it will have twice the kinetic energy.
The speed (or velocity) of an object has a squared relationship to its kinetic energy.
If you double the speed of an object, its kinetic energy increases by fourfold.
BallisticsStudy of the characteristics of projectiles in motion and effects upon objects impactedFactors affecting energy exchange between a projectile and body tissue:
VelocityProfileStabilityExpansion and fragmentationSecondary ImpactsShape
BallisticsVelocity
Causes trajectoryFaster = straighter trajectorySlower = more curved due to gravity
BallisticsProfile
Portion of bullet you see as it travels toward you
Larger profile = greater energy exchange
CaliberDiameter of a bullet (ID of gun)
0.22 caliber = 0.22 inches
Bullets become unstable as they pass from one medium to another.
Collection of Robert Porter
BallisticsStability
Bullet length increases bullet tumblingCan reduce the accuracy of the shotReduced by rifling in barrel (spinning)
YawGyroscopic effect on the center axis of the bullet that reduces tumbling
Tumbling of bullet once it strikes objectIncreases rate of energy exchangeGreater tissue damage
BallisticsExpansion and Fragmentation
Results in increased profileMushroomingInitial impact forces may result in fragmentingGreater tissue damage
Both: Collection of Robert Porter
BallisticsSecondary Impacts
Bullet striking other objects can cause yaw and tumbleBody armor (Kevlar)
Transmits energy throughout entire vest resulting in blunt trauma
Myocardial contusionPulmonary contusionRib fractures
BallisticsShape
Handgun ammunition is rather blunt More resistant to travel through human tissueReleases kinetic energy more quickly
Rifle bullets are more pointed and cut through the tissue more efficiently
May tumble or fragment
Specific Weapon CharacteristicsHandguns
Often a small-caliber, short-barreled, medium-velocity weapon Severity of injury is related to the organs directly damaged by the bullet’s passage
Collection of Robert Porter
Rifles
Specific Weapon Characteristics
RifleHeavier projectile Longer barrel Greater muzzle velocityBullet travels much farther, with greater accuracy, and retains much more of its kinetic energy Collection of Robert Porter
Specific Weapon Characteristics
Assault RifleGenerally has a larger magazine capacity
Multiple wounds and casualties can be expected Will fire in both the semiautomatic and automatic mode
Specific Weapon Characteristics
ShotgunMay fire a single projectile (a slug) or numerous spheres (pellets or shot) at medium velocity
The larger the shot, the smaller the number of projectiles
http://www.youtube.com/watch?v=vQvqESdCk7U
Specific Weapon Characteristics
Knives and ArrowsSlow-moving, penetrating objects cause low-velocity, low-energy wounds
Usually limited to physical injury caused by direct contact between the blade or object and the victim’s tissue
Hunting tips designed for arrows can be especially damaging
Biomechanics of Penetrating Trauma Direct Injury
Occurs as the projectile strikes tissue, contuses and tears that tissue, and displaces the tissue Limited to the profile of the bullet as it moves through the body Handgun bullet damage is usually limited to direct injury
Biomechanics of Penetrating Trauma
Pressure Shock WaveWhen a high-velocity high-energy projectile strikes human tissue, it creates a pressure shock wave. The faster and more blunt the bullet, the greater the effect.
Biomechanics of Penetrating TraumaTemporary Cavity
Space created behind the high-energy bullet as tissue moves rapidly away from the bullet’s path
After the bullet’s passage, tissue elasticity causes the temporary cavity to close
Cavitation
Biomechanics of Penetrating TraumaPermanent Cavity
Tissue may not return to its normal orientation, resulting in a permanent cavity
Cavity fills with debris
Zone of InjuryZone of injury extends beyond the permanent cavity May be slow to heal
Low Velocity Wounds
Low-Velocity WoundsObjects
Knives, ice-picks, arrowsFlying objects or debris
Injury limited to tissue impactedObject pathwayObject twisting or movedOblique angle
Attacker CharacteristicsMales: outward and crosswiseFemales: overhand and downward
Specific Tissue/Organ Injuries
Specific Tissue/Organ Injuries
Connective TissueAbsorbs energy and limits tissue damage
OrgansSolid organs
Dense and low resilienceHemorrhage associated with solid organ projectile damage is often severe
Hollow organsFluid filled: transmit energy = increased damageAir filled: absorb energy = less damage
Connective TissueIncluding muscles and skinDense, elastic, hold together well‘Absorb energy while limiting tissue damage’Damage is limited to projectile’s pathway
Solid OrgansLiver, spleen, kidneys, pancreas, brainHave density but not resiliency Hemorrhage is often severeDamage outside of the profile
Hollow OrgansBowel, stomach, heart, bladderMuscular and hold fluidIf filled with fluid, organ may tear explosivelyIf filled with air (not distended), injury toleratedPericardial tamponade
Specific Tissue/Organ Injuries
LungsAir in lung absorbs energyParenchyma is compressed and reboundsPneumothorax or hemothorax can result
BoneResists displacement until it shattersAlters projectile path
General Body RegionsExtremities
Injury limited to resiliency of tissue60–80% of injuries with <10% mortality
Do not immediately threaten lifeInjuries above the elbow or knee are more likely to cause significant vascular injury
Abdomen (includes pelvis)Highly susceptible to injury and hemorrhageBowel perforation: 12–24 hrs. peritoneal irritation
General Body RegionsThorax
Rib impact results in explosive energy.Heart and great vessels have extensive damage due to lack of fluid compression.Any large chest wound compromises breathing.
General Body RegionsNeck
Damages trachea and blood vesselsNeurological problemsSucking neck wound
HeadCavitational energy trapped inside skullSerious bleeding, lethal
Wound CharacteristicsEntrance Wounds
Size of bullet profile for non-deforming bulletsDeforming projectiles may cause large woundsClose range
Powder burns (tattooing of powder)
Exit WoundsAppear to be “blown” outward
Pressure wave
© Edward T. Dickinson, MD
Special Concerns WithPenetrating Trauma
Special Concerns WithPenetrating Trauma
Scene Size-upLaw enforcement
DO NOT ENTER UNTIL SCENE IS SAFE!
Weapons: victim or assailantPreserve crime scene when possible
© Mikael Karlsson/On Scene Photography
Special Concerns WithPenetrating Trauma
Penetrating Wound AssessmentTry to determine the pathway of the penetrating object
Internal organ injury potentialEntrance and exit wounds
Special Concerns WithPenetrating Trauma
Penetrating Wound Care
Facial woundsFacial gunshot wounds destroy many airway landmarks
Cricothyrotomy may provide temporary airway care
Collection of Robert Porter
Special Concerns WithPenetrating Trauma
Penetrating Wound CareChest wounds
Requires a large wound to be present for air to move into the chest cavity
Open pnuemothoraxTension pnuemothorax
Consider the possibility of heart and great vessel damage
Pericardial tamponade
Special Concerns WithPenetrating Trauma
Impaled ObjectsLow energyDangerous to removeDo not remove unless:
In cheek, neck, or tracheaInterferes with CPR
SummaryIntroduction to Penetrating TraumaKinetics of Penetrating TraumaSpecific Tissue/Organ InjuriesSpecial Concerns with Penetrating Trauma