Go Boom, Fall Down: Ballistics, Gunshot Wounds and the Human Body. Jeff Solheim, MSN RN CEN TCRN CFRN FAEN

Transcription

1 OBJECTIVES: 1. Participants will be able t define ballistics 2. Participants will be able t describe three factrs which influence wunds in gunsht injuries. 3. Participants will be able t anticipate ptential trauma team respnse needs fr gunsht victims based n firearm descriptin. Ballistics (study f the mvement f a bullet) The basics f bullet mvement A cartridge cntains: Casing the utside f the cartridge which cntains the gunpwder and the bullet Primer prtin f the cartridge at the prximal end which causes a spark when struck Gunpwder explsive material cntained within the casing. Bullet the prjectile in the distal prtin f the casing that exits when the gunpwder ignites and expands. When the trigger is pulled, a firing pin within the firearm strikes the primer, causing a spark, which in turn ignites the gunpwder within the casing. As the gunpwder is ignited, it changes frm a slid t a gas. Because gas cnsumes mre rm than a slid, there is an expansin within the casing that prpels the bullet ut f the frnt f the cartridge dwn the barrel f the firearm. The barrel is grved, causing the bullet t spin. This spinning gives the bullet mre stability as it mves thrugh the air after leaving the barrel. Wunding ptential a number f different factrs will affect the wunds that are inflicted n smene wh is struck by a firearm: Bullet size the larger the bullet, the mre severe tissue damage is likely t be. The size f a bullet is reprted as the diameter f the missile at its widest pint. This is als knwn as the caliber. The caliber is reprted in 1/100 th f an inch r in millimeters. The firearm used t prpel the bullet must have a barrel that matches the size f the bullet. If the barrel is larger, the bullet will wbble within the barrel and will be ejected at an awkward angle, less likely t hit its target. A bullet that is larger than the barrel may get stuck, leading t an explsin within the firearm. A 22 caliber bullet is 22/100 th f an inch in diameter at its widest pint. A 9 millimeter rund is 9 millimeters at its widest pint. 22 and 25 caliber prjectiles are cnsidered small caliber. 32 thrugh 38 caliber prjectiles are cnsidered medium caliber Calibers abve 40 are cnsidered large caliber.

2 Bullet mass the heavier a bullet, the mre damage it is likely t inflict. Bullets f equal caliber may be a different weight, therefre causing different wunding ptentials. Bullet velcity the faster a bullet is mving when it strikes an bject r persn, the mre damage it is likely t cause. Velcity is dependent n: Amunt f gunpwder within the casing Type f firearm used Handguns small, easily cncealed shrt-barreled guns designed t be held and fired in ne hand. Rifles lng-barreled guns, less easy t cnceal and designed fr lng range accuracy. Rifles tend t have greater velcity and ptential fr damage because f: Lnger barrel lnger time fr expanding gases frm the cartridge t prpel the bullet frm the end f the barrel. Rifle ammunitin tends t cntain mre gunpwder giving it a higher velcity leaving the barrel. Distance f target frm the firearm prjectiles will slw dwn as they mve thrugh the air after leaving the barrel, therefre, the farther frm the firearm the victim is, the less energy the bullet will tend t have and the less the wunding ptential will tend t be. The appearance f the wund caused by the bullet may give hints as t the distance the individual was frm the firearm. A gun will tend t prpel mre than the bullet frm its barrel, ther substances prpelled include: Carbn mnxide and ther flaming gases (will travel apprximately 2 inches befre falling away) St (will travel 6 7 inches befre falling away) Unburned pwder Tight cntact cutaneus wunds caused by a gun being held against the skin when fired carbn mnxide will give the wund edges a red disclratin, and charring frm flaming gases will be nted n the wund edges. Clse cntact cutaneus wunds st as well as stippling frm gunpwder will be nted n the skin. St can be wiped away, but stippling cannt. Mid-range cutaneus wunds There will be n burns r st, but stippling may be nted arund the bullet wund. Lng-range cutaneus wunds absence f st, stippling r burns, rather a simple hle with an abrasin arund it. If the abrasin is circumferential, the bullet likely struck the surface at a 90 degree angle. If the abrasin Stellate r star-shaped wunds ccur when a gun is fired directly ver a bny surface. Irregular wunds are caused by bullets tumbling befre striking the victim, ften frm being fired thrugh a windw r ther slid bjet prir t striking the persn.

3 is uneven, then the bullet likely struck the skin at the pint where the abrasin is the mst nticeable. Type f bullet Bullets are ften made f sft lead that will defrm when they meet resistance, such as tissue. Sme bullets are cmpletely cvered with a harder metal such as cpper that is unlikely t defrm. If the entire bullet is cvered with a mre stable metal, it is referred t as a full-metal jacket and is less likely t defrm when it strikes an bject. Sme bullets are partially cvered with a mre stable metal such as cpper, but the tip is left uncvered. When the uncvered surface meets resistance, such as striking an bject r tissue, it flattens and becmes wider. It may even break apart int smaller fragments. This wider surface r multiple fragments will increase the energy dissipated int the tissues and increase the wunding ptential. These are called semi-jacketed bullets. Sme bullets actually have a hllw pint inside the sft metal s that when they strike a firm surface, they actually peel backwards like a mushrm. This dissipates the energy laterally and decreases frward mvement f the prjectile, causing extensive damage in the area where the prjectile cmes t rest. These are called hllw-pint bullets. Effects f bullets n tissues Lw velcity bullets (travelling less than 1000 feet per secnd) tend t pass directly thrugh tissue, crushing everything in their path. This is referred t as crushing r permanent cavity ) Full metal jackets are required by internatinal law t be used in warfare. A full metal jacket will tend t pass right thrugh a persn, causing damage between the entrance pint and the exit pint, but minimizing the damage between. This neutralizes the target, but is less likely t kill the target. Hllw pint bullets are used by law enfrcement, because they will expand within the persn wh is struck, causing maximal damage, mre likely stpping them and the expanding bullet is less likely t exit the persn, striking inncent bystanders. High velcity bullets tend t create a pressure wave within tissue that frces the tissue away frm the permanent cavity fr a shrt perid f time. This is referred t as cavitatin r temprary cavity and can cause injuries that extend far beynd the actual permanent cavity. In very high velcity gunsht wunds, shck waves may precede the bullet, causing injuries t rgans and tissues a great distance away frm the permanent cavity.

4 Bullets may als break apart, causing widespread damage as the varius pieces f the bullet travel thrugh tissue. Bullets may als tumble r wbble (yaw) s that the narrwest prtin f the prjectile des nt lead the way. In these cases, the wund that is created will be significantly larger. Different tissues react differently t prjectiles. Higher density tissues (liver, spleen, brain) have little elasticity and are mre likely t be significantly injured. Tissue with higher elasticity (lung and muscle) will tend t suffer less damage as they can stretch and fall back int their riginal psitins with less permanent damage. Bne the effects n bne will depend n the velcity f the prjectile when it strikes the bne: High velcity may shatter the bne Mid-velcity may break the bne but spare it frm shattering Lw velcity may cause the bullet t break int pieces withut damaging the bne, but causing extensive damage arund the site where the bullet struck the bne. Lw velcity bullets may als ricchet ff f bne and take a different path thrugh the bdy than the riginal trajectry, resulting in tissue damage in places ther than thse expected by the entrance wund. Exit wunds Nt all gunsht victims will have an exit wund. If the bullet disintegrated, mushrmed, defrmed, r riccheted, it may remain within the bdy. Nt all exit wunds are larger than entrance wunds. Full metal jackets f lw velcity may create nthing mre than a permanent cavity whse exit size will clsely apprximate the entrance wund. The exit will lack the abrasin that is seen n the entrance wund. High velcity bullets r bullets that defrm and exit will likely carry large vlumes f tissue ut with them, resulting in exit wunds that are a different size than entrance wunds. Shtgun wunds Unlike a single prjectile frm a handgun r rifle, shtgun shells cntain multiple metal pellets knwn as sht. Large pellets are knwn as bucksht, small pellets as birdsht. A cartridge generally nly carries ne size pellet. As the pellets leave the barrel, their velcity rapidly decreases. The farther they are frm the barrel the greater the distance between the pellets.

5 Therefre, shtgun blasts at clse range can result in devastating tissue damage as a large number f pellets enter int a small area at a great velcity. As the distance between the barrel and the victim increases, velcity decreases and the distance between the pellets increase, decreasing ptential tissue damage. There is mre likely t be small wunds spread ver a large surface area in lngrange shtgun wunds. Shtgun shells are measured in gauge rather than caliber. The higher the gauge, the smaller the diameter. Bibligraphy Barry, R. M. (2004). Penetrating chest wunds. RN, 67 (5), Christffel, K. K. (2007). Firearm injuries: epidemic then, endemic nw. American jurnal f public health, 97 (4), Dentn, J. S., Segvia, A., & Filkins, J. A. (2006). Practical pathlgy f gunsht wunds. Arch Pathl Lab Med, Eckert, K. L. (2005). Penetrating and blunt abdminal trauma. Crit Care Nurs Q, 28 (1), Freidlander, E. (2008). Vilence, accidents, pisning. Retrieved July 8, 2008, frm The pathlgy guy: Peitzman, A. B., Rhdes, M., Schwab, C. W., Yealy, D. M., & Fabian, T. C. (2007). The trauma manual: trauma and acute care surgery. Philadelphia : Lippinctt Williams and Wilkins. Phillips, B. (2002). Gunsht wund t the chest: the effect and impact f high-velcity gun shts. Jurnal f rescue and disaster medicine, 3 (2). Pdgrny, G., & Stanley, L. (2002). Gunsht victims. RN, 45, Russell, M. A., & Nguchi, T. (1999). Gunsht wunds and ballistics: Frensic cncerns. Tp Emerg Med, 21 (3), Silvia, A. J. (1999). Mechanism f injury in gunsht wudns: myths and reality. Crit Care Nurse Q, 22 (1),