HIGH VELOCITY GUNSHOT WOUNDS OF THE CHESTf B. T . L E R O U X C h .M . F .R .C .S .* iUNlE 1978 F I S I O T E R A P I E Die e ffe k te van m isie le varieer m e t s p o e d en tipe, massa en v lu g e ie n sk a p p e . N ie slegs die g ro o tte nie, maar die g e p a ardgaande s k o k g o lw e en ty d e lik e k avitasie veroorsaak le tte r lik o n tp lo ffe n d e v ern ie tig in g van long- weefsel. T h o ra c ic tr a u m a is c o n v e n tio n a lly c lassified as “ c l o s e d ” a n d “ o p e n ” . M o s t c lo sed in ju rie s a r e th e re su lt 0f r a p id d e c e le ra tio n — fa llin g f r o m a h e ig h t (the c o m m o n b u ild in g i n d u s try a c c id e n t), c ru s h in g (th e c o m ­ mon m in in g a c c id e n t) a n d h ig h sp e e d traffic a c c id e n ts (the “ste e rin g w h e e l” in ju ry ). T h e c o m p re ss iv e effects 0f b la s t c a n p r o d u c e in ju rie s in d is tin g u is h a b le f r o m those o f ra p id d e c e le ra tio n . I n c iv ilia n life m o s t “o p e n ” injuries, in w h ic h th e r e is a b re a c h in th e c h est w a ll, are less w id e ly d e s tru c tiv e ; th e c o m m o n in ju rie s a re *rom low v e lo c ity m is sile s a n d knives. I m p a le m e n t, say 0n a p ie c e o f p ic k e t fe n c in g , m a y b e a n a c c o m p a n im e n t of h ig h sp e e d a c c id e n ts, a n d re te n tio n o f a tra n s fix in g foreign b o d y is th e n a n a d d e d th e r a p e u tic p ro b le m . T h e d e s tru c tiv e effect o f m is sile s v a rie s w ith th e ir velocity a n d th e ty p e , w e ig h t a n d flig h t c h a ra c te ris tic s of th e m issile . V e lo c ity — n o w classified as low , m edium a n d h ig h — w as little c o n s id e re d u n til th e in tro d u c tio n o f h ig h v e lo c ity m issile s, a n d th e re a d y a v a ila b ility to so ld ie rs a n d u r b a n g u e rilla s o f th e w eapons a b le to fire su c h m issile s. T h e d a m a g e in ­ flicted by a low v e lo c ity (less th a n 1 2 0 0 ft. p e r sec.) bullet, e v en a t c lo se ra n g e , d e p e n d s m o re o n th e ty p e a nd flight c h a ra c te ris tic s o f th e m is sile th a n o n v e lo c ity . Spin, yaw , p re c e ssio n , n u ta t io n , tu m b le — th e s e a re all term s u se d to d e s c rib e flig h t c h a ra c te ris tic s a n d a ll m o d ify th e e x te n t o f tis su e d a m a g e c o n s e q u e n t u p o n the p a ssa g e o f a m issile . B u lle ts w h ic h e x p a n d o r frag m e n t o n im p a c t w ill c le a rly a lso in flic t g re a te r da m a g e th a n th o se th a t d o n o t. N o tw ith s ta n d in g , low velocity m issile s in g e n e ra l d a m a g e th e lu n g s s u r ­ p risin g ly little — so m u c h so th a t it w as a n a p h o ris m d u rin g th e 1 9 3 9 - 4 5 w a r th a t, if to b e s h o t w as u n ­ a v o id a b le , it w a s p re fe r a b le to be s h o t in th e chest, e sp e cially in th e r ig h t h a lf o f th e chest. D iffe re n t a re h ig h v e lo c ity in ju rie s . H ig h v e lo c ity "m issiles (th o se th a t tra v e l a t a sp e e d g r e a te r th a n I 500 ft. p e r sec.) e v en if o f sm a ll c a lib re , p r o d u c e an -'e n tire ly d iffe re n t ra n g e o f in ju rie s re la te d d ire c tly to th e s p e e d o f th e m is sile th r o u g h tissu e . T o th e la c e r a t­ ing a n d c ru s h in g effect o f im p a c t a n d th e ph y sic al tra n s it o f th e m is sile th ro u g h tissu e s a r e a d d e d th e d e stru c tiv e effects o f b o th sh o c k w a v es a n d te m p o r a r y c a v ita tio n , a n d m is sile s o f a v e lo c ity o f 4 - 5 000 ft. p e r second p ro d u c e te m p o r a r y c a v ita tio n o f lite r a lly ex­ p lo siv e d e stru c tiv e n e ss. O n im p a c t, a m is sile c o m p re ss e s th e m e d iu m s tru c k and th is re g io n o f c o m p re s s io n d isp e rse s as a s h o c k w ave o f s p h e ric a l fo rm , w ith a v e lo c ity slig h tly g re a te r th a n th a t o f so u n d in w a te r (4 800 ft/sec ) — th a t is, its * P r o f . o f T h o r a c ic S u rg e ry /U n iv e rs ity o f N a ta l, f A p a p e r d e liv e re d a t a T r a u m a C o n g re ss f o r P h y s io ­ th e ra p is ts h e ld in D u r b a n , M a y 1977. a d v a n c e th ro u g h tissu e s is th a t o f th e h ig h e r v e lo c ity m issile s. S h o c k w a v e s a r e b o th tr a n s m itte d th ro u g h a n d re fle cte d f r o m in te rfa c e s in th e ir p a th , so t h a t p re s s u re c h an g e s a t a n y o n e p o i n t m ay , b y a u g m e n ta tio n o r c a n ­ c e lla tio n , b e v e ry co m p le x . P re s s u re c h a n g e s p ro d u c e d b y sh o c k w av es a r e o f s h o rt d u r a tio n ( 1 5 - 2 5 m il li­ se c o n d s) b u t m a y re a c h 1 000 lb /sq . in. W ith th e p a ssa g e o f h ig h v e lo c ity m is sile s th r o u g h tissu e s in w h ic h v ita l o rg a n s a re n o t d ire c tly s tru c k , sh o c k w av es a re lik e ly to b o u n c e off b o n e b u t c a n be v e ry d a m a g in g to th e g as c o n ta in in g v isc e ra — g u t a n d lu n g . A s a m is sile p e n e tra te s it a c c e le ra te s th e m e d iu m stru c k , f o rw a rd s a n d la te ra lly , w ith su c h f o r c e — a n d th e g r e a te r th e v e lo c ity o f th e m is s ile th e g r e a te r th e f o rc e — t h a t th e c o m p o s ite p a rtic le s o f th e m e d iu m o r tissu e , c o n se q u e n t u p o n th e i r in e rtia , c o n tin u e to b e d is p la c e d a w a y f r o m th e p a th o f th e m issile f o r se v e ra l m illis e c o n d s a f te r th e m is sile h a s tra v e rs e d th e b o d y , so th a t th e m issile tra c t (d e fin e d as th e p e rm a n e n t tissue d e fe c t in th e p a th o f th e m issile), is e x p a n d e d in to a cavity, c alled th e te m p o ra ry c a v ity (d e fin e d as th e tis su e d e fe c t a t th e in s ta n t o f m is sile flig h t th ro u g h th e tissu e ), w h ic h c o lla p ses q u ic k ly . P re s s u re in th e te m ­ p o r a ry c a v ity is s u b a tm o s p h e ric a n d c o n te n ts in c lu d e v a p o u r f r o m th e tissu e s tra v e rs e d a n d e n tr a in e d a ir. T h e siz e o f th e p e r m a n e n t tis su e d e fe c t d e p e n d s o n th e v o lu m e o f tis su e lo st th ro u g h e n tra n c e a n d e x it w o u n d s a n d th e v o lu m e o f a ir tr a p p e d w h e n th e te m p o r a r y c a v ity fin a lly co lla p ses, w h ic h it d o e s in a se rie s o f e x p a n s io n s a n d c o n tra c tio n s o f d im in is h in g a m p litu d e . T h e siz e o f th e te m p o r a r y c a v ity a n d th e n u m b e r o f p u ls a tio n s o r v o lu m e c h an g e s in d u c e d d e p e n d o n th e v e lo c ity o f th e m is sile , b u t p u ls a tio n s m a y e x te n d o v e r m o re th a n 2 0 m illis e c o n d s a n d th e te m p o r a r y c a v ity m a y b e m o re th a n 30 to 40 tim e s th e v o lu m e o f th e p e rm a n e n t cav ity . A t v e lo c itie s b e lo w a 1 000 feet/sec . te m p o r a r y c a v ita tio n is o f little m o m e n t. A t h ig h v e lo c itie s te m p o r a r y c a v ita tio n is v e ry m u c h m o re d a m a g in g th a n a re sh o c k w aves. N e g a tiv e p re s s u re in th e te m p o r a r y c a v ity m ay su c k in c lo th in g a n d o th e r d e b ris . P u ls a tio n m ay e x tru d e tis su e f r o m th e e n tra n c e w o u n d — a n e v e rsio n p h e n o m e n o n c a lle d ta il sp la sh . A t th e h ig h e r v e lo c itie s o f m is sile tra v e rs e th r o u g h tissu e s, th e r a p id it y a n d th e e x te n t o f e x p a n s io n o f th e te m p o r a r y c a v ity m a y b e so v io le n t t h a t th e e la s tic ity of a d ja c e n t s tru c tu re s m ay n o t b e a b le to c o n ta in it a n d th e effect is e x p lo siv e a n d im p lo siv e , m im ic k in g th e u se o f e x p lo s iv e b u lle ts. T h u s , th e p a ssa g e o f a h ig h v e lo c ity b u lle t th ro u g h th e h e a d w ill e x p lo d e th e sk u ll; th r o u g h th e a b d o m e n , w ill e x p lo d e g u t; a n d th ro u g h th e chest, w ill e x p lo d e lu n g . A n d w h ile th e e a rly ra d io g r a p h ic f e a tu re s of lu n g d a m a g e — p n e u m o th o ra x , h a e m o th o ra x , a n d p u l­ m o n a ry h a e m a to m a — m a y be little d iffe re n t fro m th o se p ro d u c e d b y lo w v e lo c ity m is sile , th e p a ssa g e th ro u g h th e lu n g o f a h ig h v e lo c ity m is sile so d is r u p ts th e lung o v e r so w id e a n a r e a th a t ra d io g r a p h ic e v id e n c e o f d a m a g e is in g ra v e sc e n t a n d th e n e e d r e g u la rly a ris e s fo r p u lm o n a r y re se c tio n , e s s e n tia lly f o r re m o v a l o f ir r e p a r a b ly d a m a g e d p u lm o n a ry its su e w re n c h e d f r o m its b lo o d su p p ly . R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )