《GeneralG13GunshotWoundsSirkin》由会员分享，可在线阅读，更多相关《GeneralG13GunshotWoundsSirkin（52页珍藏版）》请在金锄头文库上搜索。
1、Gunshot Wounds,Michael Sirkin, MD Chief, Orthopaedic Trauma Service Assistant Professor, New Jersey Medical School North Jersey Orthopaedic Institute Created March 2004; Reviewed March 2006, August 2010,Ballistics,Most bullets made of lead alloy High specific gravity Maximal mass Less effect of air
2、resistance Bullet tips Pointed Round Flat Hollow,Low velocity bullets Made of low melting point lead alloys If fired from high velocity they melt, 2 to friction Deform Change missile ballistics High velocity bullets Coated or jacketed with a harder metal High temperature coating Less deformity when
3、fired,Ballistics,Velocity,Energy = mv2 Energy increases by the square of the velocity and linearly with the mass Velocity of missile is the most important factor determining amount of energy and subsequent tissue damage,Kinetic Energy of High and Low Velocity Firearms,Kinetic Energy of Shotgun Shell
4、s,Wounding power,Low velocity, less severe Less than 1000 ft/sec Less than 230 grams High velocity, very destructive Greater than 2000 ft/sec Weight less than 150 grams Shotguns, very destructive at close range About 1200 ft/sec Weight up to 870 grams,Factors that cause tissue damage,Crush and lacer
5、ation Secondary missiles Cavitation Shock wave,Crush and Laceration,Principle mechanism in low velocity gunshot wounds Material in path is crushed or lacerated The kinetic energy is dissipated Increased tissue damage with yaw or tumble Increased profile Increased rate of kinetic energy dissipation I
6、ncreased probability of fragmentation,Secondary Missiles,Bone fragments or metal fragments from helmet that move through tissue and cause damage Highly destructive Erratic, unpredictable, and unexpected courses,Cavitation,Primarily with high velocity missiles Low velocity missiles tend to push tissu
7、e aside Path of destruction only slightly larger than bullet,Cavitation,High energy Energy is dissipated forward and laterally away from the bullet and tract At high velocity the cavity continues to enlarge even after bullet has passed,Cavitation,Cavity is sub atmospheric (negative pressure) Sucks a
8、ir and debris from both ends Initial cavity is temporary Collapse and reforms repeatedly with diminished amplitude Results in greater tissue damage to inelastic tisse (liver, spleen) than elastic tissue (e.g. lung) Missile path that remains is permanent cavity,Cavitation,Vessels, nerves, and other s
9、tructures that were never in contact with bullet may be damaged In tissues with low-tensile strength (organs), cavitation develops more rapidly and extensively Muscle is intermediate in tensile strength Bone and tendon have high-tensile strength,Cavitation,At higher velocity Entrance wound may be la
10、rger than bullet If bullets yaws, deforms, fragments, tumbles, cavitation may be extensive and asymmetric Entrance wound may be modest Maybe no exit wound if entire energy of bullet is dissipated in / absorbed by the tissue.,Cavitation,If the path of the bullet is short Bullet may exit as degradatio
11、n of the energy is beginning to increase secondary to yaw and deformation of the bullet Large exit wounds,Cavitation,Long path of bullet Energy degradation occurs deep in tissues Large amount of damage through cavitation Entrance and exit wounds may be small,Shock Wave,With higher velocities damage
12、to tissue away from are of impact can occur Tissue in front of projectile is compressed Moves away in form of shock wave At about speed of sound in water 4800 ft/sec Faster than bullet (except very high velocity) Thus, nerve impairment with bullet wound does not indicate nerve transection,Shotguns,O
13、ther factors in injury Wadding Plastic Paper Cork Embeds into wound Contaminates wound, infection Must be identified and removed,Shotguns,Missile A few to hundreds Spherical Relatively high muzzle velocity 1000-1500 ft/sec Massive wounding capacity at 4 to 5 feet Projectiles slow down quickly,Conclu
14、sions,High velocity gunshots may cause massive amounts tissue damage requiring debridement Close range shotgun wounds also cause massive tissue destruction Both may have large amounts of contamination Secondary to negative pressure of cavitation Shell casing, wading etc. Thorough surgical debridemen
15、t is imperative,Evaluation,Careful inspection Locate all entrance and exit wounds Check circulation Look for expanding hematoma X-rays of injured extremities and areas Angiography when necessary Discrepancy of pulses,Management,Low velocity gunshot wounds rarely need debridement High velocity and cl
16、ose range shotgun wounds always need debridement Most civilian gunshot wounds are low velocity and low energy,Bullets are not Sterile,Old myth that bullet was sterile from heat Wolf et al: Coated bullet with S. aureus and shot into sterile gelatin block Positive cultures grew from gelatin,Wolf, J Trauma, 1978,Infection,Low velocity gunshot wounds in stable fractures do not need surgical debridement Oral antibiotics for 72 hours as effective as IV IV antibiotics not indicated unless for pro
