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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


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


Assault RifleGenerally has a larger magazine capacity

Multiple wounds and casualties can be expected Will fire in both the semiautomatic and automatic mode


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





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


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


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


Scene Size-upLaw enforcement

DO NOT ENTER UNTIL SCENE IS SAFE!

Weapons: victim or assailantPreserve crime scene when possible

© Mikael Karlsson/On Scene Photography


Penetrating Wound AssessmentTry to determine the pathway of the penetrating object

Internal organ injury potentialEntrance and exit wounds


Penetrating Wound Care

Facial woundsFacial gunshot wounds destroy many airway landmarks

Cricothyrotomy may provide temporary airway care



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


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