jUNE, 1973 P H Y S I O T H E R A P Y ULTRA SOUND AS I SEE IT E. J. W O O D , L e c tu rer in P hysiotherapy, U .C .T . iA A A A A A A A A A A A A ^ W V W V W ' W Page 3 . a rtjcie is fo r p h y sio th era p ists w hose tra in in g did n o t i He ( j |tra S ound. It will a tte m p t to answ er, in very '• nip terms, such q u e stio n s a s :— siniPW hat is U ltra S o u n d ? How can U ltra S o u n d be p ro d u c e d ? How d o U ltra S o u n d waves b e h a v e ? Effects o f U ltra S o u n d on h u m a n tissue. For w hat c o n d itio n s sh o u ld U ltr a S o u n d be used ? W hat dangers a re th ere in tre a tm e n t? Technique o f a p p lic atio n . Latest developm ents. WHAT IS U L T R A S O U N D ? S o u n d waves a re lo n g titu d in a l waves in c o n tra s t to the ♦ sverse waves o f light. T h is m eans th e re is a to a n d fro c em en t o f particles in a vertical p lan e a n d th is m ovem ent ' ■ t r a n s m i t t e d from p a rticle to p a rticle in a m ed iu m . T he disturbance is tran sm itte d th e p articles d o n o t m o v e from one end o f the m edium to the o th e r. A t o ne m o m e n t the particles are pushed to g eth e r — k n o w n as com pression a nd at another they a re p u lle d a p a r t — ra re fa ctio n . WHY DO WE CALL T H E M W AVES? “Waves” is a term given to a pe rio d ic d istu rb a n c e of particles in a m edium a n d this d istu rb a n c e c a n be c o n v en ien t- , |y represented g raphically as a w ave form . d ir e c t io n o f w ave The compression is rep re se n ted by dipeak o f energy. The rarefaction is re p re se n ted by th e troughs. ' distance betw een a n y tw o p eaks is the wavelength. .e rate a t which successive p eak s pass a given p o in t is the frequency. The speed a t w hich waves m ove is th e velocity. The distance each pa rticle m oves is th e amplitude. There is a rela tio n sh ip betw een velocity, w avelength and frequency in th a t: Velocity = F re q u e n cy x W avelength If the velocity is c o n sta n t, i.e. if so u n d w aves a re travelling in the same m edium , the waves w ith th e h ighest frequency will have the sm allest w avelength. T h is fa c to r a c c o u n ts fo r *"e differences betw een a u d ib le so u n d , w ith a freq u e n c y up I®1" 0 0 0 cycles/sec. a n d a w avelength m ea su re d in cm s; a n d the Ultra Sound we use, w ith a freq u e n c y o f 1 m egac./sec. an2 ,a wavelength o f o nly 1 J m m . lh ,velocity o r ra te a t w hich th e d istu rb a n c e will pass n iS a med*um varies a n d d e p en d s o n th e size and umber of the a to m s in the m edium . In gases th e velocity is i n n 3S t*le a to m s a re fa r a p a r t a n d th e p ush is n o t easily . A u dible so u n d , w ith its lo n g er w avelength is emitted in a ir b u t U ltra S o u n d as we use it is n o t. well^h s p e c ia lly w a ter tra n s m it U ltra S o u n d re aso n a b ly locked i so*‘ds tra n s m it best o f all as th e m olecules are closely to g eth e r a n d th e p u sh is easily tra n s m itte d . H ow ever tran sm issio n also d e pends o n the elasticity o f the m edium a s well as the density. In o th e r w ords, its a b ility to re tu rn to its o riginal sh a p e a fte r d e fo rm a tio n , a n d som e solids d o th is b e tte r th a n o th ers. T o u rm a lin e has th e highest velocity o f U ltra S o u n d tran sm issio n . P R O D U C T IO N O F ULTR A S O U N D P iezoelectric effect It w as fo u n d th a t a v ib ra tin g c ry stal had a difference o f p o ten tial o n its o p p o site faces. C onversely it w as also fo u n d ■ th a t if a n a lte rn a tin g p o te n tia l difference was ap p lie d to the crystal it w o u ld v ib rate. T h is a lte rn a tin g p o ten tial difference m ust be a t th e sam e freq u en cy as the n a tu ra l freq u e n c y o f the crystal. Q u a rtz is used fo r the c rystal because it is c h e a p ; d oes n o t re q u ire a high degree o f en erg y to keep it vib ratin g , o nly a b o u t 100 V., a n d its coefficient o f ex p an sio n is low. CIRCU IT B asically a high freq u en cy a lte rn a tin g c u rre n t is p ro d u c ed by disc h arg in g a c o n d e n s o r th ro u g h a n in d u cta n ce , w ith a valve to give the k ick a t th e right m o m e n t, like p u shing a swing. T h is c u rre n t is a p p lie d to th e specially c u t q u a rtz on o p p o site faces a n d the q u a rtz is b o nded to a m etal d ia p h ra g m . T his p a rt is k n o w n as th e tra n s d u c e r. T he b o n d in g is difficult a n d expensive. All t h a t is no w necessary is a v a ria b le resistance to increase the a m p litu d e , i.e. th e a m o u n t o f p u sh to e ach p article. Pulsed so u n d is also p ro d u c ed w ith 1:10 o r 1:5. S o u n d : silence ra tio . A s th e c rystal dilates — co m p re ssio n , as it re tra cts, ra re fa ctio n . H O W D O ULTR A S O U N D W AV ES BEHAVE? F ro m a p o in t source, s o u n d waves a re c o n ce n tric a n d spherical. U ltra S o u n d is u su ally p ro d u c e d by a disc therefore it is n o t a p o in t so u rc e a n d waves a re p lan e waves. D iv e r­ gence is m inim al d u e to th e sm all w avelength so sonic e nergy c a n be ro u g h ly ta k e n to beam o u t in a lm o st parallel b eam s fro m th e h ead. T h ere is a co m p lica te d in te r­ ference p a tte rn n e a r to th e h ead a n d in som e m ach in es th e c la m p in g o f th e c rystal re su lts in m o re m ovem ent in th e c entre. T o d istrib u te th e in tensity evenly it is necessary to keep th e h e a d m o ving w hen tre a tin g w ith c o n tin u o u s so u n d to e n su re even p o w e r d istrib u tio n in th e tissues, a n d to p re v en t to o m uch energy in o n e area. W h en sonic energy strik es a m ed iu m , th e energy m ay b e :— Reflected R e frac te d A b so rb e d a n d T ra n sm itte d . R E FLEC TIO N Y o u m u st all have w a tched waves h ittin g a cliff a n d being reflected off. T h e cliff fo rm s a n ob sta cle to the waves. T he rocks reflect all the w a ter b u t th e soil will b o th reflect a n d a b s o rb som e. W e a re talk in g here o f w aves trav e llin g in one m edium (w ater) re ac tin g in a c ertain w ay w hen th e re is a c hange o f m edium (th e cliff). U ltra S o u n d behaves in th e sam e way. W e have a lre a d y seen th a t tran sm issio n o f U ltra S o u n d d e p en d s o n the e lasticity o f th e m ed iu m . I f tw o m edia have th e sa m e a b ility to tra n s m it U ltr a S ou n d — this is k n o w n as th e c h ara cte ristic aco u stic im pedance — there will be n o reflection a t th e b o u n d a ry betw een th e tw o. W here one su b sta n c e tra n s m its well a n d the o th e r bad ly , there will be a high degree o f reflection. In o th e r w ords, reflection occu rs a t the inte rfac e betw een tw o m edia w hich tra n s m it U ltra S o u n d differently. T h is p ro p e rty affects o u r tec hniques o f trea tm e n t. 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. ) Page 4 ] . A ir does n ot transm it Ultra Sound. T h e re fo re U ltra S o u n d energy leaving th e tre a tm e n t h e a d w ill be im m ediately reflected b a ck in to th e h e a d w ith a b u ild up o f energy. I t h a s b een said th a t th is c a n s h a tte r th e q u a rtz , b u t I th in k in fact it is m o re likely to d isru p t th e b o n d in g o f th e q u a rtz to th e m e ta l d ia p h ra g m . T h e re ­ fo re : D o n o t tu r n o n so n ic o u tp u t w ith th e h e a d in air. 2. I n o rd e r to tra n s m it energy in to th e tissues we m u st h a v e som e m ed iu m to rep lace th e a ir betw een th e so u n d h e a d a n d th e skin. T his is the coupling m edium . T o re d u c e reflection th e m ed iu m u sed sh o u ld h ave a co u stic p ro p e rties betw een th e m etal o f th e h e a d a n d th e tissues. W a te r fulfills this p u rp o se b u t it is n o t alw ays co n v en ien t to a p p ly a s it r u n s off a n d m ust a lso be free o f a ir b u b b les. T h e p a rt c a n be im m ersed in w a ter o r a sm all ru b b e r b a g c a n be filled w ith w a ter a n d a p p lie d betw een h e a d a n d skin. I t is still necessary in th is case to in tro d u c e a n o th e r c o u p la n t to re d u c e th e a ir betw een h e a d a n d b a g a n d skin. T he m o st c o m m o n ly used c o u p la n t is a n oil o f som e so rt u se d betw een th e so u n d h e a d a n d skin w hich is sufficiently viscous n o t to r u n off th e a re a b e ing tre a te d . G ly c ero l is o n e o f th e b e st as it tra n s m its U ltra S o u n d well b u t it is expensive. L iq u id P araffin is o fte n used, a t som e h o sp itals w ith 0 .0 5 % th y m o l to re d u ce c ross-infection. T he w ater based tra d e b ra n d s a re g o o d b u t expensive. 3. B o n e reflects U ltra S o u n d hig h ly therefore avoid superficial bone. U ltra s o u n d w ith its sm all w av elen g th is reflected m o re easily th a n a u d ib le so u n d . A n a n alo g y t h a t m a y h e lp in u n d e rsta n d in g th is fact is a b rick in a sm all p u d d le will reflect sm all waves we m a y m a k e w ith o u r h a n d s b u t in a la rg e r p o n d w ith la rg e r w aves th ey w ill b e n d ro u n d th e b rick o r sim ply pass o ver it. I t d e p en d s o n th e size o f th e ob sta cle in re la tio n to th e w avelength. O n e last p o in t o n reflection is th e n eed to k eep th e so u n d h e a d in c o n ta c t w ith th e skin all th e tim e, o therw ise if som e p a r t lifts o ff U ltra S o u n d is tra n s m itte d b a c k in to th e h e ad w h ich m ay h e a t a n d th e n be u n c o m fo rta b le to th e p a tie n t w h en it a g a in to uches th e skin. O f c o u rse on ly th e p a r t in c o n ta c t will be tra n s m ittin g a n d th e efficiency o f th e tre a t­ m e n t will b e reduced. A n o th e r fa c to r governing th e n eed to m a in ta in c o n s ta n t c o n ta c t w ith th e sk in w hen usin g oil, is R efrac tio n 11 Y o u all k n o w h o w light waves b e n d w hen p a ssin g th ro u g h different m ed ia — lo o k a t y o u r fo o t in a b a th . U ltra S o u n d d oes th e sam e a n d ten d s to b e n d u p w a rd s, re d u cin g th e d e p th o f p e n e tra tio n . A t a n incid e n t a n g le o f m o re th a n 15 degrees th e re fra c te d b e a m is 90 degrees th e re fo re th e re is n o tr a n s ­ m issio n o f U ltra S o u n d in to th e tissues. W h e n u sed u n d e r w a te r th e re is o nly m in im al re fra c tio n a n d th is does n o t a p p ly . R e fra c tio n d e pends o n th e velocity o f th e w ave w hich d e p en d s o n th e d e nsity a n d elasticity o f th e m ed iu m . I f th e m ed ia differ m a rk e d ly th e re w ill b e m o re re fra c tio n th a n if th e m ed ia a re very alike. A bsorption a nd T ransm ission T h ese tw o fa c to rs a re ob v io u sly in te rd ep e n d e n t as th e m o re a b s o rp tio n in th e tissu e th e less will be tra n s m itte d . As th e so n ic en erg y e n te rs a tissue a c e rta in a m o u n t o f th a t e n erg y is u sed u p c ausing th e m olecules o f th a t tissue to m ove. T h is is k n o w n as hysteresis a n d th e h ig h er th e hysteresis o r e nergy necessary to cause th e m o v em e n t th e m o re th a t tissue will a b s o rb U ltra S o u n d c o n v e rtin g sonic e n erg y in to m o v e ­ m e n t a n d th e less it will tra n s m it U ltra S o u n d . B one absorbs Ultra S o u n d a lm o st c o m pletely a n d w ith in th e first 5 m m o f p e n e tra tio n . U ltim a te ly a ll sonic e nergy a b so rb e d in th e tissues is c o n v e rte d to h e at. W hat in f a c t do we m ean by heat ? T o d iscuss th is we m first c o n sid e r energy. Y o u all k n o w th a t energy is n™Usl lost, it is sim ply c o n v erted fro m o n e fo rm t o a n o th e r. T h ^ a re tw o ty p es o f energy, p o te n tia l a nd k inetic. K in e tic ene is th e e nergy o f m ov em e n t, a n d th e re a re tw o type/ 8 1 k in etic energy, directional a n d random . W h en c u rre n t pas a lo n g a w ire this is d irec tio n a l k in etic e nergy b u t in Ses p a ssa g e m olecules o n th e fringe a re k n o c k ed a n d thI*S n o rm a l degree o f m o v em e n t is increased. T his is rando k in etic energy. In a ra d ia to r b a r th is increase in rando1" k in etic en erg y is sufficient to p ro d u c e h e a t. W hich brings m b a c k to th e p o in t w h a t do w e m ea n by h e a t ? A table maS feel c ool to y o u , b u t th e ta b le w o u ld feel h o t to a n ice block- th e re fo re h e a t is rela tiv e , a n d o ne b o d y is h o tte r tha a n o th e r if w hen in c o n ta c t h e a t flows fro m th e o ne to th o th e r. T h e c h a ir y o u a re sittin g o n w ill b e w a rm when yof s ta n d u p . I n fa ct w h a t is b e ing tra n s m itte d w hen heat i tra n s m itte d is th e m o v em e n t o f m olecules. T he h otter bodv h a s a h ig h e r degree o f ra n d o m kin etic e nergy a n d when in c o n ta c t w ith a c o o le r b o d y w hose m olecules a re m oving more slow ly th e energy fro m th e o n e passes to th e o th e r until the average kin etic energy o f th e tw o a re th e sam e a n d they are th en a t th e sam e te m p e ra tu re . S o if we increase th e aver?' k in etic e nergy o f th e m olecules o f a su b sta n c e we ' p ro d u c in g h e a t a n d th is is w h a t u ltra s o u n d does. Increase o f th e m o v em e n t o f m olecules in th e tissues. I n h u m a n tissue th o se su b sta n c es w ith a hig h w ater content will h a v e a low hysteresis, i.e. low e nergy consum ption to c au se m o v em e n t, a n d will n o t a b s o rb as m u c h U ltra Sound a n d th e re fo re n o t b e h e a te d as m u c h as tissues w ith a high hysteresis w hich will a b s o rb a h ig h d egree o f U ltra Sound and th ere fo re p ro d u c e m o re h e a t, a n d tra n s m it little o r n o Ultra S o u n d . S k in , f a t a n d m uscle have a low hysteresis, fibrous tissue, bone a n d cartilage high. W h e n co n sid erin g tra n s m iss io n in th e tissues w e m ust also re m e m b e r reflection a n d re fra c tio n a t th e interfaces between th e different tissues a n d we find th a t sonic e nergy is reduced to h a lf its su rfa c e in te n sity a t 5 cm d e p th u sin g a Imegacyclc o u tp u t d u e to b o th a b s o rp tio n a n d re fra c tio n a n d reflection. T h is is k n o w n as th e h a lf v a lu e th ic k n e ss a n d one must th ere fo re c o n sid e r th e d e p th o f th e tissue w e wish to heat w hen se ttin g o u t o u tp u t. L et us c o n sid er n o w th e e nergy p a ssin g th ro u g h the usual a rra n g e m e n t o f tissue w e in so n a te . T h e re is n o t a g re at deal o f re flection betw een skin, su b c u ta n e o u s tissue a n d fa t, b u t th e re is obviously some a b so rp tio n . T he fib ro u s sh e a th o f th e m uscle will reflect to so m e ex te n t, th e n th e e nergy p asses th ro u g h th e individual m uscle fibres b e ing a b so rb e d o n its w ay a n d again more energy is reflected fro m th e sh e a th o n th e fa r side. When f w aves re a c h th e p e rio ste u m som e is reflected b u t the m effect o n th is tissu e is d u e to it’s close p ro x im ity to bone, as we h a v e a lre ad y seen, b o n e reflects U ltra S o u n d highly and a b so rb s th e re m a in in g e nergy very ra p id ly . T h is m eans there is a b u ild up o f e nergy in th e p e rio ste u m b o th due to the reflection fro m th e b o n e , A N D , as th e h ig h degree ol a b s o rp tio n in th e b o n e m ea n s a ra p id h e a tin g o f bone and b o n e c o n d u c ts h e a t b a d ly , d issip a tio n o f th is h e at is no! m o re deeply in to th e b o n e b u t im m ediately o u t to the p e rio ste u m . T h is tissue c o n ta in s m a n y sensory nerve endings a n d w e all k n o w th a t sensory re c e p to rs o f a ll kinds re g iste r p a in w h e n stim u la te d b e y o n d th e ir tolerance. The aching, burning p a in is the danger signal in Ultra Sound tha' y o u r in te n sity is to o high. W h en th e in te n sity is b elow this d a n g e r level, h e at will be co n d u c te d from , these deeper stru c tu re s a n d will on':; register as w a rm th if it is sufficient to filter th ro u g h to tw ( te m p e ra tu re re ce p to rs in th e derm is. O ften a patient fw*> w a rm th o nly som e tim e a fte r tre a tm e n t. T h e thing re m e m b e r th o u g h , is t h a t h e a t is b e ing p ro d u c e d a t a deep’ level, in fact th is is th e a d v a n ta g e o f U ltra Sound ove d ia th e rm y in th a t fa t is n o t h e a te d w ith U ltra Sound an one c a n c au se d eeper tissue h e atin g . JUNE, i 973P H Y S I O T H E R A P Y 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. ) JUNE- 1973 P H Y S I O T H E R A P Y Page 5 0f u ltra Sound on Human Tissue a e one en ters th e c o n tro v e rsy o f th e rm a l versus n o n - Here nm m ints n a rtlv to a Q uestion o f d e cid in e a t w h a tal It a m o u n ts p a rtly to a q u e stio n o f d e ciding a t w h a t therm? m ovem ent m ech an ic al energy a n d a t w h a t p o in t is it P0lt V o u r physics d e p a rtm e n t suggest it d e p en d s w hich heat - - QU a re sittin g o n ! T h ere is n o d o u b t th a t th e OlCC __. n f T T ltr a S m i n H a r p t h r w f i n f h f t a tolosical effects o f U ltra S o u n d a re th o s e o f h e at. p*?uSthf>r there a re a n y g ro u n d s fo r saying t h a t som e o f^ViTther there a re a n y g ro u n d s to r saying t n a t som e 0 1 w n et g reater th a n c o u ld be p ro d u c e d by h e a t a n d a re ' ^ ^ f o r e due to th e p re ssu re o f th e m o v em e n t o f th e m ole- __t hey h ave a very h ig h a cc ele ratio n — is a m a tte r fo r cuies « x ex Slir«e’ ^ b a t e a n d n o t yet successfully p ro v e n . T h e effects on human tissue a p p e a r to be Increase in b lo o d flow. Increase in cell m e m b ra n e perm eability. Increase in m eta b o lism — d e n a tu rin g o f p ro te in if too hot. Pain th resh o ld raised. Inflam m atory cellu la r response. Fibrous tissue m o re extensible. Muscle spasm re d u ce d . Of these increase in cell m em brane p e rm e a b ility is o ften •^rmed a m echanical effect due to w a te r m olecules being n o c k e d off th e m e m b ra n e w hich th e n dries, sh rin k s a n d th e nores enlarge. I f y o u w ere o n th e m e m b ra n e y o u w o u ld class the m ovem ent o f th e w a te r as m ech an ic al b u t if y ou were on the w a ter m olecule y o u w o u ld get h o t m o ving o u t of the way. I t com es b a c k to w hich m o lecule y o u a re sitting on. Improving th e e x ten sib ility o f fib ro u s tissue m ay b e d u e to the pressure involved w hich d isru p ts th e co lla g en fibers in the matrix o r m erely d u e to so fte n in g o f th e m a trix itself. Muscle Spasm is said to be relieved by h e a tin g re d u cin g the susceptibility o f th e m uscle spindles a n d th e g a m m a efferents, but there a p p e a r to be n o g ro u n d s fo r th e belief t h a t it acts in this way. The re lie f o f p a in by h e a t is a n o th e r th o rn y problem , lscheamic p ain is easily relieved by th e increase in b lo o d supply. P a in fro m m uscle spasm w o u ld be relieved if th e spasm were relieved. T h e effects o n n e rv e itself a p p e a r to cause destruction a t low energies o f U ltra S o u n d o r only very transient in te rru p tio n o f fu n c tio n . One m ust alw ays re m e m b e r th a t e xpression o f p a in is governed by e m o tio n a n d th a t th e h a n d lin g o f a p a tie n t will go a long w ay to relieving p ain regardless o f w h a t m o d ality is used. 5. For what conditions should ultra sound be used? Here there a re so m an y conflicting o p in io n s th a t it is .impossible to sta te a n y th in g definitely. O n e c a n re a d o f enefits to one c o n d itio n u sing several different dosages in •ne same pub lic a tio n t h a t states U ltra S o u n d w as o f n o value at all. T oo o ften th e re a re several m o d alitie s u sed a n d it is not possible to sta te w ith a n y degree o f co n fid en ce th a t U ltra Sound was th e m a in fa c to r involved. In one article o n sh o u ld e r h a n d sy n d ro m e , h o t p ack s a n d whirl-pool a n d U ltra S o u n d a n d active a n d passive m ove­ ments were used. O n e m u st a lso n ever o v e rlo o k “ th e te n d e r loving care” p a rt o f tre a tm e n t a n d th e p ow er o f suggestion. For myself I w o u ld suggest use U ltra S o u n d as a c o n venient method of a p p lying h e a t to stru c tu re s such as te n d o n a n d capsules a n d m uscle a tta c h m e n ts to b o n e w here th e a re a is small and localised a n d alw ays follow u p w ith th e m ain p a rt °* treatment w hich is m ovem ent. 1 see no p o in t in giving a p a tie n t b o th U ltra S o u n d a n d short Wave. I t is difficult to feel th a t h e a t c o u ld be used to relieve pain a t spinal n erve ro o ts as th e b o n e o f th e lam in ae would prevent en erg y p e n e tra tin g th a t fa r. C onversely it would be unwise to in so n a te a lam in ec to m y sc a r fo r fear of amaging the c o rd w h ich is n o t th e n so p ro tec te d . f e l e d scars w o u ld be b e nefitted a n d th e re a p p e a rs to be ' i" ce o f benefit to D u p y tr o n ’s c o n tra c tu re . N e w w ou n d s ould I feel be a c o n tra in d ic a tio n , as th e very effects o f U ltra S o u n d a re destru ctiv e in th e in itia l h e aling process o f fibrous tissu e a n d h ave b e en sh o w n to p ro d u c e a c u te in fla m m a tio n a n d w orse scarring. I w o u ld suggest th ree w eeks as th e very e arliest to use U ltra S o u n d in th is field. R e g e n e ra tio n o f tissue has b een accele rated in a r a b b it’s e ar, if u sin g only 0,5 w /c m 2 fo r 5 m ins. M o re th a n th is cau sed d e stru c tio n a n d less, n o effect. T o tra n s la te th is to a h u m a n g ra v ita tio n a l u lcer is difficult as th e c o n d itio n s a re very different. So fa r evidence o f benefit is n o t e n co u ra g in g w ith th e sk in o fte n b re a k in g dow n , th o u g h o th ers feel u ltra so u n d is o f som e use. I n m ild in fla m m a to ry c o n d itio n s a low in te n sity m ay ju s t a ccelerate b lo o d flow sufficiently to h elp re so lu tio n w ith o u t increasing c o ngestion. H ow ever m em b ra n e pe rm e ab ility is a lso in cre ased a n d h y p e rae m ia in a n y fo rm will increase o edem a. T h e best m e th o d o f re d u cin g oedem a rem ain s m ovem ent. In recent traum a th e effects o f U ltra S o u n d a re a g ain w idely d e b a te d . A g re at d eal d e pends o n w h a t o n e m eans by re c e n t? I f im m e d ia te, i.e. th e n e x t day, U ltra S o u n d is o b v iously c o n tra in d ic a te d to th e in itial h e alin g process. T h is h a s b e en sh o w n clinically. O ne m u st a sk o neself if in fact a n y effects a re possible a t th e low doses som e p e ople use w hich a re said to be beneficial. I n re ce n t lite ra tu re , fo o t­ ballers w ith injuries h a v e b e en tre a te d by hig h intensities fo r lo n g perio d s several tim es a day. T h e effect o f this a p p e a rs to h a v e b een th e d e stru c tio n o f th e n erve cells w hich re m o v e d p a in , th e re fo re a ctive m o v em e n t w as possible. A s these n erv es a re superficial a n d n o t d a m a g ed fo r a n y great len g th th e y a p p e a r t o re g en e rate q u ite q u ickly b u t it seems ra th e r a d ra stic m e th o d o f p a in relief. D A N G E R S I n c o n sid erin g d a n g ers, th e c o n tra in d ic a tio n s m u st first b e listed. A g a in c o n tro v e rsy . H o w ev e r it w o u ld a p p e a r w iser n o t to t r e a t : B ra in tissue. E yes — da m a g e to th e lens. T u m o u rs — d ispersal o f m a lig n a n t em boli. P re g n a n t u te ru s — h a e m o rrh a g e due to te a rin g o f p lacenta. R e p ro d u c tiv e organs. T u b erc u lo sis, sepsis o f b o n e o r so ft tissue. R e c e n t h a e m o rrh a g e a n d h a em o p h ilia. A fte r deep X -ra y th e ra p y — devitalises th e skin. P e rip h era l V a sc u lar D isease as th e re is a d a n g er o f tissue necrosis d u e to h e at n o t b e ing dissipated. B U R N S a re th e o b v io u s d a n g e r w ith th e p e riosteal p a in being th e d a n g e r signal. O V E R D O S E th e c o n d itio n e x ac erb a ted u su a lly by in ­ c rea sin g congestion. C A V IT A T IO N does n o t o c cu r a t th era p eu tica lly u sed levels. E L E C T R IC S H O C K as a p plies to th e use o f a n y faulty a p p a ra tu s . T E C H N IQ U E O F A P P L IC A T IO N A N D D O S A G E S 1. T est m ac h in e — in sm all bow l o f w ater, n o t w ith w a ter o n so u n d h ead. 2. T est sk in fo r h o t a n d c o ld se n sa tio n — a lth o u g h perio ste al p a in is th e first t o be stim u la te d , th e sam e n e rv e supplies th e skin so a defect th e re m ig h t p re su p p o se a defect in th e perio ste al nerves as well. 3. U se a su itab le c o u p lin g m edium . I t is n o t necessary to increase dose in w a te r as a tte n u a tio n is slight over th e distan c e we use w hich is a b o u t 2 cm s. W ipe off b u b b le s o r use degassed w a te r to p revent reflection. 4. C o v e r a n a rea a b o u t th re e tim es th e size o f th e tre a tm e n t h e ad . 5. A v o id superficial b o n e a n d n e rv e o r u se very low dose. 6 . K e ep h e a d m o v in g if usin g c o n tin u o u s U ltra S ound. 7. K e ep h e ad in c o n ta c t w ith d irec t coupling. 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. ) Page 6 P H Y S I O T H E R A P Y JUNE, 1973 TH E p r e s e n t s - M i n i d y n e m k III T R A N S IS T O R IS E D F A R A D IC U N IT Representing another advance in the evolution of the Minidyne, the M ark III version cSu°inr?earisda r UitS ^ ",du" tHe Size bUt a'S° "h an W . 'llEblg! control with output sufficient for all forms ofwide range of surge speed faradic techniques Wel1 a.s visua! indi?ation of sur3e speed enabling the operator to anticipate a muscle reaction without having to watch the control panel Ever Ready PP9 batteries which will give up to six months' use without replacement and are obtainable worldwide W E IG H T reduced to: 4 lbs. (1,8 kg) SIZ E reduced to 8 " x 5 * " x 2 * " (20 cm x 13,5 cm x 6 cm). PRICE: R 8 7 , 5 0 complete with accessories. M E D I C A L D I S T R I B U T O R S C A P E Y O R K | 252 JEPPE ST. | JO H A N N E S B U R G | D e Waal House, 172 Victoria Road I WnoH^tnri, r p P L EA SE A D D R E S S A L L C O R R E S P O N D E N C E TO P.O. B O X R IG A S S E B L IE F A LLE K O R R E S P O N D E N S IE A A N P O SB U S 3378 JO H A N N E S B U R G TEL. A D D . ‘D IS M E D ’ PH O N E | F O O N 23-8106 TELEX: 43-7129 S.A. 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. ) JUNE, 1973 P H Y S I O T H E R A P Y Page 7 d o s a g e s Expressed in W a tts /c m 2 o f tre a tm e n t h e a d X tim e. T rea tm e n t h e a d u su a lly 5cm 2 a n d to ta l o u tp u t o f m ac h in e 1 5 w atts, th e re fo re m a x im u m a v ailab le is 3 W /c m 2. f o r c h onic c o n d itio n s s ta rt a t 0,5 m in s a n d w o rk up to 1 5 W /c m 2 o r 2 W /c m 2 d e p e n d in g o n p a tie n t’s tole ran c e a nd m achine. A cute c o n d itio n s, low d o sa g e and. s h o rt tim e to s ta rt, 0,25 \V/cma fo r 3 m ins. T ry in c h ro n ic c o n d itio n s to re a c h o p tim u m d o sa g e fo r W atts in th re e tre a tm e n ts th e n increase th e tim e by 1 o r 2 m ins p e r tre a tm e n t. L im it t o 12 — 15 tre a tm e n ts . L atest re a d in g — d isa p p o in tin g , n o th in g new . b i b l i o g r a p h y Bass, A . L . 1966 R o y . Soc. M e d . 59: 653-6. B ie r man, W. 1954 A rch. P hys. M e d . 35, 209. Brown & Gordon 1967 U ltrasound techniques in B iology & M edicine. B uchan, J . F. 1970 P ractitioner 205: 319-26. D yson, M . and Pond, J. B . 1970 P hysiotherapy, April. G oodm an, C. R . 1971 W y S ta te S M e d . 71: 559-62. Gordon, 1964 Ultrasound a s a diagnostic and surgical tool. L ic h t, S . 1959 Therapeutic H eat. N elson, P . A . 1950 A rch. P hys. M ed. 31-6. P hys. Ther. Jan 1971 P 51: S3. Proc. R . Soc. M e d . 1971 64: 996-7. Soren, A . 1969 M e d . Tim es 971219-25. S u m m er a n d P a tric k 1964 Ultrasonic Therapy. Van N ostrand, 1962 Physics, a basic Science. W right, E . T. et a l 1971 Arch. P hys. M ed. a n d Rehab. 52 280-1. A C K N O W LED G EM EN TS B uchow iecki, D r. J. 1972 D ept, o f Physics. U .C .T . G uyton, Prof. A . C. 1968 L ecture to M edical Students. S loan, P rof. A . W . 1972 D ept, o f P hysiology U.C.T. PREMIXED NITROUS OXIDE AN D OXYGEN - A REVIEW J. F . C O E T Z E E , B .S c ., M .B ., C h .B ., (U niv. Stell.), D e partm ent o f A naesthesia, K arl B rem er H ospital, B elh ille . A p h y sio th e ra p ist is o ften c o n fro n te d w ith th e p ro b lem o f having to tre a t a p a tie n t w h o is in p a in . I f a d e q u a te p a in relief is n o t o b ta in e d , th e n n o t o nly is th e tre a tm e n t less effective, b u t it is alw ays disa g ree ab le fo r th e p a tie n t. T h e use o f p o te n t n a rc o tic analgesics d oes n o t solve th is pro b lem . I f given in a d e q u a te d o sa g e to p ro v id e effective p a in relief, the p a tie n t o fte n h a s re sp ira to ry d ep ressio n a n d is d row sy a n d u n c o -o p era tiv e . T h e ideal analgesic a d ju v a n t fo r use d u rin g p h y sio th e ra p y sh o u ld h a v e th e fo llo w in g p ro p e rtie s : I t sh o u ld p ro v id e p ro fo u n d a n alg esia w ith m inim al h y p n o sis — i.e. a co n sc io u s, c o -o p era tiv e p a tie n t free o f p ain. 1 . 2. 4 ' y 4. 5. A d m in is tra tio n sh o u ld involve a sim ple tec h n iq u e. I t sh o u ld b e sufficiently free o f d a n g e ro u s side effects, to e n a b le a d m in is tra tio n to be p e rfo rm e d by tra in e d p h y sio th e ra p ists w hile n o t u n d e r d irec t m edical supervision. I t sh o u ld n o t be h a b it fo rm in g . I t sh o u ld n o t in te rfere w ith o r w o rsen diseases th a t th e p a tie n t m a y have. S u ch a n a g e n t m a y p ro v e to be n itro u s oxide. History, Physical and Pharmacological Properties o f Nitrous Oxide N itro u s O xide (Syn., N itro g e n m o n o x id e ; F o rm u la , N 20 ) js a c o lourless g a s w ith a fa in t sw eetish o d o u r. I t is su p p lied in b lu e cy lin d ers in to w hich it h a s b een c o m p re ssed to a pressure o f 650 lb /s q . in. A t th is p re ssu re , N 20 is in a liquid form . A s it is re le ased fro m th e cy lin d e r it re tu rn s to th e gaseous sta te . I t is n o n flam m able. N 20 is th e o ld est o f th e gaseo u s a n ae sth etic a g en ts. I t was first p re p a re d by P rie stle y in 1776. I n 1779 H u m p h re y D a v y afte r e x p erim e n ts o n him self, 1 a n n o u n c e d th a t it h a d a n a e s­ th etic p ro p e rties, a n d suggested th a t it be used to relieve p ain. H is su g gestion w ent u n h e ed e d u n til 1844 w hen C o lto n a d m in istere d N aO to W ells w hile a d e n tist e x tra c te d o n e o f W ells’ tee th . W ells’ la te r a tte m p t to in tro d u c e N 20 a s a n a n a e sth e tic ag en t m et w ith ridicule w hen d u rin g th e d e m o n s tra tio n th e p a tie n t cried o u t. In 1868 A nd rew s in tro d u c e d oxygen a d m in istra tio n w ith n itro u s oxide in th e m a n n e r o f its p re se n t-d a y use. T h e e a rly tec h n iq u es o f a d m in isterin g n itro u s oxide were by giving th e p u re gas. M a n y o f th e effects a n d accidents w hich w ere a sc rib e d to N 20 were th e resu lts o f hypoxia. P ro v id e d sufficient oxygen (21% o r above) is given, th e effects o n b o d y system s a re slight. O n th e c entral n e rv o u s system , th e effect d e p en d s o n th e c o n c e n tra tio n in h ale d . N itro u s o xide h a s g o o d analgesic p ro p e rtie s w hile it is a w eak a n ae sth etic a gent. G . D . P a r b r o o k 1 , 2 show ed th a t a m ix tu re o f 2 5 % n itro u s oxide w ith 7 5 % oxygen p rovides b e tte r a n algesia th a n 15 m g o f m o rp h in e . H e show ed th a t a fte r ceasing to in h ale 2 5 % n itro u s oxide, significant a n algesia p ersisted fo r five m inutes, a n d d isa p p e a re d a fte r 15 m inutes. I f c o n c e n tra tio n s o f 5 0% a n d a b o v e a re in h ale d , consciousness is usually lost. W ith su b a n a e sth e tic c o n c e n tra tio n s, a feeling o f e u p h o ria is o ften experienced — h ence th e n a m e “ lau g h in g g as” . S e n so ry effects in clu d e tingling, n u m b n ess, dizziness as well as a u d ito ry a n d visual d istu rb an c es. A t th e hig h er c o n c e n tra tio n s n a u se a a n d co n fu sio n m ay a p p e a r. N a u se a is p a rtic u la rly likely if h y p o x ia is p re sen t. D e p ressio n o f th e re s p ira to ry c en tre does n o t occur. H a b itu a tio n is a possible h a z a rd w ith re p ea te d use, especially in p e rso n s w ho te n d to becom e e u p h o ric . T h e re is n o effect o n b ro n c h ia l secretions. P u lse a n d b lo o d p re ssu re re m a in u n c h an g e d , th e re b e in g n o d irect a c tio n on . th e h e a rt. S om e im p ro v e m e n t o f p e rip h e ra l b lo o d flow does occur. K id n e y a n d liver fu n c tio n s a re unaffected. D e p ressio n o f sk eletal m u sc u la r to n e is m in im al. S m o o th m uscle is unaffected. D e p ressio n o f b o n e m a rro w fu n c tio n in leu k o - p a e n ia o nly o ccu rs if n itro u s oxide is in h ale d c o n tin u o u sly fo r m o re th a n 24-48 h o u rs . 8 , 4 N itro u s oxide is re a so n a b ly in so lu b le in th e b lo o d . U p ta k e a n d ex cre tio n via th e lungs is ra p id . I ts effects a re th e re fo re ra p id ly a c tin g a n d q u ick ly w ear off a fte r te rm in a tin g a d m in is tra tio n . 5 T o d a y n itro u s o xide is used in th e m a jo rity 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. )