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1、Penetrating Trauma,Sections,Introduction to Penetrating Trauma Physics of Penetrating Trauma Specific Tissue/Organ Injuries Special Concerns with Penetrating Trauma,38,000 Deaths in US annually due to shootings. Mechanisms of penetrating trauma Knives, Arrows, Nails, etc Understanding principles of
2、energy exchange increase the Index of Suspicion associated with the MOI,Introduction to Penetrating Trauma,Recall Kinetic Energy EquationGreater the mass the greater the energy Double mass = double KE Greater the speed the greater the energy Double speed = 4x increase KE,Physics of Penetrating Traum
3、a,(continued),Physics of Penetrating Trauma,Small & Fast bullet can cause greater damage than large and slow. Different bullets of different weights traveling at different speeds cause Low Energy/Low Velocity Knives and arrows Medium Energy/Medium Velocity Weapons Handguns, shotguns, low-powered rif
4、les 250-400 mps High Energy/High Velocity Assault Rifles 600-1,000 mps,(continued),Physics of Penetrating Trauma,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 backwar
5、d and absorbs energy Recoil,(continued),Physics of Penetrating Trauma,Remainder of energy propels bullet forward at a high rate of speed. Trajectory is curved due to gravity As bullet strikes object, it slows and energy is transferred to object. Law of Conservation of Energy,Ballistics,Study of the
6、characteristics of projectiles in motion and effects upon objects impacted Factors affecting energy exchange between a projectile and body tissue Velocity Profile Stability Expansion & Fragmentation Secondary Impacts Shape,Energy Dissipation,Drag: wind resistance Cavitation: formation of a partial v
7、acuum and cavity within a semi-fluid medium Profile: Size and shape of a projectile as it contacts a target Larger the profile=greater energy exchange Expansion and fragmentation results in damage Stability Allows for straighter trajectory Decreases after striking object results in tumbling,Aspects
8、of Ballistics,Velocity Causes Trajectory Faster = straighter trajectory Slower = more curved due to gravity,Aspects of Ballistics,Profile Portion of bullet you see as it travels towards you Larger profile = greater energy exchange Caliber Diameter of a bullet (ID of gun) 0.22 caliber = 0.22 inches B
9、ullets become unstable as they pass from one medium to another.,Aspects of Ballistics,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
10、 bullet once it strikes object Reduces kinetic energy Greater tissue damage,Bullet Gyroscopic Effect,Aspects of Ballistics,Expansion & Fragmentation Results in increased profile Mushrooming Initial impact forces may result in fragmenting Greater tissue damage,Aspects of Ballistics,Secondary Impacts
11、Bullet striking other objects can cause yaw and tumble Body Armor (Kevlar) Transmits energy throughout entire vest resulting in blunt trauma Myocardial Contusion Pulmonary Contusion Rib Fractures Shape Handgun Ammunition = Blunt = Tumble Rifle Ammunition = Pointed = Piercing,Handguns Small caliber,
12、short barrel, medium-velocity Effective at close range Severity of injury based upon organs damaged Rifle High-velocity, longer barrel, large caliber Increased accuracy at far distances Assault Rifles Large magazine, semi- or full-automatic Similar injury to hunting rifles Multiple wounds,Specific W
13、eapon Characteristics,Shotgun 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 Low-energy & low-velocity Damage related to depth and angle of attack Movement of the victim can increase dam
14、age,Specific Weapon Characteristics,Damage Pathway,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
15、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 Temporary Cavity Due to cavitation Permanent Cavity Due to seriously damaged tissue
16、Zone of Injury Area that extends beyond the area of permanent injury,Ballistics Cavitation,Low-Velocity Wounds,Objects Knives, Ice-picks, Arrows Flying objects or debris Injury limited to tissue impacted Object pathway Object twisting or moved Oblique angle Attacker Characteristics Males: outward an
17、d crosswise Females: overhand and downward,Density of tissue affects the efficiency of energy transmission Resiliency Strength and elasticity of an object Connective Tissue Absorbs energy and limits tissue damage Organs Solid Organs Dense and low resilience Hollow Organs Fluid filled: transmit energy = increased damage Air filled: absorbs energy = less damage,
