Physiotherap y, Ju n e 1982, vol 38, no 2 31 RESPONSES OF SUPERFICIAL AND DEEP BLOOD VESSELS TO COOLING G. M I T C H E L L , * J. E N S L I N , f M. M A S T R O L O N A R D O , t B. S H U N N , f a n d A. S T E W A R T f SU M M A RY D ilation o f b lood vessels se e m s desirable f r o m a therapeutic p o in t o f view. R esults suggest that application o f icepacks m ay not be the ideal technique to use, as icepacks, although low ering sk in tem perature to levels a t which sk in vessels will dilate, w ill not lower m uscle tem peratures to levels at which deep vessel constriction is inhibited. R esu lts fu r th e r show that to achieve dilation o f vessels, it is not necessary to apply icepacks f o r longer than 8 - 1 0 minutes. O P S O M M IN G D ilatasie van bloedvate b ly k w enslik te wees van ’n terapeutiese standpunt. R esu lta te dui daarop dat die aanwending van y s p a k k e nie die ideale tegniek is nie aangesien y sp a k k e , wat w el die v eltem peratuur verlaag to t v la k k e waar die huidvate sal dilateer, nie spiertemperatuur verlaag tot vlakke waar d ie p v a a tsa m e tre k k in g inhibeer word nie. R esu lta te dui o o k aan dat, om dilatasie van vale te bew erkstellig, dit nie nodig is om y s p a k k e longer as 8 - 10 m inute aan te wend nie. IN T R O D U C T IO N O n e o f the basic as su m p t io n s o f re h ab ili ta ti on of musculoskeletal injuries is th at b l o o d flow to the injured area must be increased (Kni gh t a n d Lond ere e, 1980). Increases in bl ood flow can only be achieved if the d i am e te r o f the blo od vessel increases a n d p e rfu si on pressure rema ins con stan t. Va rious techniques are used to cause va so d ila tat io n w it ho ut affecting b l o o d pressure. Mos t of these techniques are ba sed on the o b se r v at i o n th at co ntractility o f vascular sm o o t h muscle can be affected by a n u m b e r o f physical factors such as local te m p e ra t u r e , light intensity a n d sonic vibration ( V a n h o u t t e a n d Verb eure n, 1981). O f these, tem pe ra tu re is k n ow n to have m a r k e d cffects. T hus app licatio ns of heat ( A b r a m s o n et al. 1958) a n d cold (All woo d a nd Burry, 1954; La in g et a!. 1973) hav e been used to induce va so di la ta tio n. In b o t h cases it is a ss u m e d th at t em p e ra tu r e affects the inte rac tion between cat echol amines a n d the vascular s m o o t h muscle (V a n h o u t te a n d Verbeuren, 1981). However, the precise effects o f changes in t em pe ra tu r e are unclear. The tec hnique most widely used to induce cooling is app licatio n o f icepacks. If icepacks a r e to be successful in increasing b l o o d flow to injured tissue they must lower superficial a n d deep t e m p e ra t u r e to an extent th at will cause . b l o o d vessels to dilate. We hav e exam in ed, therefore, the p f f e c t o f icepack ap pli cat ion on skin t e m p e ra t u r e and wheth er the te m p e ra t u r es p r o d u c e d by icepacks will affect blood-vessel diameter. M E T H O D T o d e te rm in e the effect o f icepacks on skin t em pe rat ur e, an icepack m ade by w ra p p i n g cr us h ed ice in a wet towel was applied to the skin o f 8 he alt hy h u m a n volunteers (5 females, 3 males). In all cases the icepack was ap p li e d to the a n te r io r surface o f the left thigh. Before ap pl ic at io n the surface t e m p e ra t u r e was mea sur ed using a cal ib rat ed alc oh ol th e r m o m e t e r . T h e b ul b o f the th e r m o m e t e r was placed a p p r o x im a t e ly in the centre o f the qu a d ric ep s muscle mass. Aft er o b t a i n i n g a steady value for skin t e m p e ra tu r e, the icepack was app lie d an d skin tem p e ra tu re was r eco rd ed at 8, 15 a n d 20 m inutes after ■‘'D e p a rt m e n t o f Physiology, University of the Wi tw at ers ra nd t D e p a r t m e n t o f Ph ys io th er ap y. University o f the Wit­ watersrand. Received 13 April 1982. ap pli cat ion o f the icepack. Aft er 20 minute s the icepack was removed. Skin t e m p e ra t u r e was then recorded at 2 m inu te intervals for 10 minute s a n d at 5 m inu te intervals f o r t h e n e x t 10 minutes. T o assess the effects o f co oling on b l o od vessels, a b d o m i n a l a o r ta s o f ra b b its were cooled in vitro. In these ex periments 9 ra bbits were given an ov erdose o f th io p e n t o n e sodi um ( l nt ra v al , M a y b a ke r ) . A segment of the ao rta was remov ed , a tt a c h e d to a 14 gauge needle, sus pe n de d in an electrolyte sol ut ion (Pl as m aly te B, Baxter) at 37°C a n d aera te d using a 95% O , , 5% C O , gas mixture (Fig. 1). Plasmolyte B re se rv o ir Syringe with adrenaline O2 S up p ly Needle (GougeV) Therm om eter S trotham venous p re ssu re tra nsducer Figure 1. T h e first series o f ex per im en ts was designed to assess the effect o f a fall in t e m p e ra t u r e fro m 37°C t o 0°C on the resistance to fluid flow t h r o u g h vessels. In these ex periments the electrolyte sol ution b a th i n g the vessel was gra dua lly cooled over a period o f 30 minutes. T he perfusing fluid was also cooled. Resistance to fluid flow was calculated fro m the fo rm u la R = / f , wh er e R = resistance, D P = perfusion pressu re a n d F = fluid flow. Perfusion pressure was m eas u re d by a tt a c h i n g a S t a th a m P23 A A venous pres sur e t r a n s d u c e r pr oximal to the artery. Pressure was record ed on a Be ckm an D y n o g r a p h calib rated to mea sur e pressures between 1 a n d 40 m m H g . Perfusion pressure was kept c o n s t a n t by m a i nt ai ni ng the height o f the reservoir c o n ta i n in g the electrolyte so lu tio n at a c o ns ta n t distanc e abo ve the artery. Flow ( m l / m i n ) at each t em p e ra tu r e was d e te r m i n e d by m ea su ri n g the time ta ke n for 20 ml o f Plasmalyte B to pass t h r ou g h the vessel. In these exp erime nts the effect o f cooling was assessed from changes in resistance. Basal resistance for each vessel was considered to be the resistance calcul ate d at 37°C. C h a n g es in the resistance o f each vessel to flow were cal culated by su b t r a ct i n g the resistance mea sur ed at te m p e ra tu r es below 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. ) 37°C from basal resistance. T h e values o b t a i n e d for change in resistance for all 9 arteries in the t e m p e r a t u r e ranges 3 6 - 30°C, 29 ̂ 20°C, 19 - 10°C, 9 -5°C a n d 4 - 0°C were pooled, a n d a value for the m ea n ch an g e in resistance was ob tained. T h e se co nd series o f exp erime nts o n isolated vessels was 'designed to s e p a ra t e an y direct effect o f c oo lin g o n bl ood vessels f ro m effects o f cooling on a dr ene rg ic neu roeffe ctor in teraction. In these exp erime nts 0,25 /ug o f ad ren ali ne was injected into the pe rfu si on fluid im mediately pr oximal to each o f the 9 arteries at t em p e ra t u r es o f 37°C, 30°C, 20°C, 10°C a n d 0°C. T h e ch an ge in resistance in du ce d by injections o f a dr en a lin e were cal culated as de scribed above. A mean valu e for change in resistance at each t e m p e ra t u r e was o b t a i n e d f r om chang es in each o f the arteries at each t em pe rat ure . R E S U L T S The effects of icepacks on skin tem peratures Figur e 2 show s the m ean skin tem p e ra t u r e o f 8 subjects d u r i n g a n d after icepack ap pl ic atio n. Basal skin tem pe ra tu re was 29,5 ± 0,4°C (55 ± S.E.M. ) Ap pl ic a tio n o f an icepack r e d d e d skin t e m p e ra t u r e significantly to 7,8 ± 1,0°C within 8 m inutes (P < 0,01, ‘t ’ test). A lt h o u g h the icepack was a pp lie d for a fu rt he r 12 min ut es no fu rt he r significant decrease in skin t e m p e ra t u r e oc cur re d. These results indicate th at icepacks reduce skin te m p e ra t u r e to a m in i m u m of a p p ro x im a t e ly 7°C in a b o u t 10 minutes. Aft er remo va l o f the icepack, skin t e m p e ra t u re increased to 20°C within 8 minutes. T h er e af t e r skin tem p e ra tu re increased relatively slowly. E x t r a p o l a t io n o f the wa rm in g curve suggests th at skin t e m p e ra t u re w o ul d reach sta rting values (29,5 ± 0,4°C) a p p r o x im a t e ly 100 min ut es after r em ov al o f the icepack. 32 Icepacks and skin temperature 0 --------- 1--------- 1--------- 1--------- 1--------- 1--------- r 0 5 10 15 2 0 2 5 3 0 3 5 Mean Minutes temp. 29-5 7 8 5-9 7 0 153 19-4 2 2 5 SEM 0 4 10 0 5 12 10 10 10 Figure 2. The effect of te m p e ra tu re on blood vessels Figur e 3 shows that c o m p a r e d t o resistance at 37°C (R = 0) a progressive decrease in m ean resistance o f 0,5; 2,4; 3,2; 2,8; a n d 3,9 m m H g / m l . min 1 o c cu rr e d in the t e m p e r a t u r e ranges 37 - 30°C, 29 - 20°C, 19 - 10°C, 9 - 5°C, a n d 4 - 0°C. These chan ge s r ep res en ted a highly significant linear correl ati on be twe en t e m p e ra t u r e a n d resistance (r = 0,90; P < 0,05). Fisioterapie, Ju n ie 1982, deel 38, n r 2 Effect of cooling Temperature (°C) Figure 3. M os t o f the ch an g e in resistance (2,9 m m H g / m l . m i n 1; 75%) o c cu r r e d in the t e m p e ra t u r e ra ng e 37 - 20°C). Figure 4 shows th at at te m p e ra t u r e s ab o v e 20°C injections o f a dr en a lin e are likely to cause a vasoc on str icti on; resistance increased in all arteries at t em p e ra t u r es of 30°C a n d 37°C. Ho w ev e r, injection o f a dr e n a li n e in to ar teries at 0°C a n d 10°C d i d no t pr o d uc e an increase in resistance c o m p a r e d to resistance at 37°C. Fig ur e 3 show s ho we ver at highly significant linear c o r re l a t i o n between decreasing tem p e ra t u r e a n d resistance in the presenc e o f a d re n a li n e (r = 0,98, P < 0,05) which suggests th at c oo lin g decreases vessel sensitivity to ad renaline. C o o l in g o f vessels has b o t h direct a n d indirect effects on vessels. T h is is sh ow n in Fig ur e 5 which was o b t a i n e d by p l o tt i n g Figures 3 a n d 4 on the sa m e axes. In this figure it is clear at all te m p e ra t u r e s ab o ve 13,5°C injections of a dr e n a li n e are able to cause a significant increase in resistance despite the decrease in resistance caus ed by cooling. T h u s vasc ula r sm o o t h muscle still res po n ds to injections o f a dr en a lin e alt h o u g h its ability to c o n tra ct is red u ce d at low t em pe rat ur e. D IS C U S S IO N Several physiological m ech ani sm s regulate b l o o d vessel diam ete r. St i m u l a ti o n o f 13-adrenergic re ceptors in vasc ula r s m o o t h muscle o r in hibition o f a - a d r e n e r g i c re cep tor s will cause re lax ati on o f sm o o t h muscle a n d b l oo d vessel d i am e te r will increase. D i l a t a ti o n will also o ccu r if vasoactive 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. ) physiotherapy, Ju n e 1982, vol 38, no 2 Effect of adrenaline Temperature (°C) Figure 4. metabolites are released in to the imme diate e nv iro nm en t of sm o ot h muscle cells. O u r results co nf irm previous findings (Allwood a n d Burry, 1954; L a i n g e / al., 1973) th at cooling blood vessels will also induce v a s o di la ta tio n a lth ou g h the mechanism is no t clear. O u r results, howe ver, suggest that v a so d i la t at io n is partly because o f direct effects o f low t e m p e ra t u r e o n b l o o d vessels. The evidence which s u p p o r t s this idea is th at in the absence pf nerves a n d neu ro eff ect or subs tan ces resistance to blo o d flow decreases linearly with decreases in t e m p e ra t u r e (Fig. 3). T h e increase in d i am e te r asso ci ate d with the fall in resistance co uld be exp lained by a re d u ct io n in the elasticity of the vessel. It has been sh o w n previously (Sc a n do la a n d Pezzin, 1978) that elastin relaxes when it is cooled a n d contracts when wa rm ed. A n o t h e r ex p la n at i o n is that sm o o th muscle m eta b ol ism is de cre as ed at low tempe ratures. How ever this ex p la n at i o n seems unlikely if the vessel is cooled mod era tely . O u r results sho w that at 30°C vascular sm o o t h muscle c o nt ra cts norm all y in the presence of adrenaline. M o r e severe c ool in g to t em pe ra tu re s o f 1 5 - 2 0°C also doe s not abo lis h vasc ula r sm o o t h muscle response to adrenaline, alt h o u g h the respo nse is dimini she d. However, below 13,5°C sm o o t h muscle does no t c o n tr a ct in the presence o f a d re n a li n e which suggests that muscle metabolism c o u ld be inhibited at low temp era tu res . O u r results a ls o indicate th at c o ol in g may indirectly cause vas odi latatio n. In vivo the indirect v a so di la to r effect o f cooling on vasc ula r s m o o t h muscle c oul d result from changes in nerve function. Synthesis a n d stora ge o f t ran sm it ter are depress ed by c oo lin g a n d coo ling decreases spo n t a n e o u s efflux o f t r a n s m i t te r subs tan ces (Va n h ou tte , 33 Effect of adrenaline and cooling Figure 5. Verbeuren a n d Webb, 1981) all o f which will reduce va so c o n st ric to r tone a n d allow the vessel to dilate. In a d d it i o n , as the vessels s h ow ed a de creasing response to ad renaline, o u r results suggest th at the sensitivity o f <*- ad ren er gic receptors may be re d u ce d by c oo lin g (Fig. 4). Fu r t h e r m o r e , a d d in g a d ren ali n e do es not cause the vessel resistance to fall t o levels below that fo un d by c ool in g alone, which suggests th at there is not an e nh an c ed 13-response at low temp era tu res . All o f these results indicate t h at , wh a te v e r the und er lyi ng m ec han ism , c o ol in g to 13,5°C o r below, causes bl oo d ve s se ls to dilate. A pp l i c a t io n o f icepacks coo ls superficial vessels to 7°C with in 10 minute s. T h u s icepacks sh o u l d cause skin vessels to dilate af ter an initial pe rio d o f co nst ric tio n ( V a n h o u t te , Ve rb eu re n a n d W eb b, 1981). F u r t h e r , since most o f the decrease in resistance which follows co oling oc cu rs in the t e m p e r a t u r e range 37 - 2 0° C (Fig. 2) it is possible that deep vessels will dilate d u r i n g icepack th era py. C a l f muscle t e m p e ra t u r e is re duced to 30 - 35°C d ur i n g icepack ap p li c at io n a n d f o r e a r m muscle falls to a b o u t 30°C when the f o r ea r m is im m e rs e d at 12°C ( B a r cr of t a n d E d h o lm , 1943). Ho w ev e r, since o u r results suggest that deep vessels are sensitive to a dr e n a li n e at all te m p e r a t u r e s a b o v e 13,5°C, st i m u l a ti o n o f sy m p a th e t ic nerve activity which will follow a p p li c a t io n o f icepacks migh t ca us e c o n st r ic tio n a n d reduce b l o o d flow to injure d muscles. In s u m m a r y d il a t io n o f b l oo d vessels seems desirable from a t h er a p eu t i c p o in t o f view. H o w ev e r , o u r results suggest 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. ) 34 Fisioterapie, J u n ie 1982, dee! 38, n r 2 th at a pp li c a t io n of icepacks may not be the ideal tec hn iq u e to use as icepacks, a l t h o u g h lowering skin te m p e r a t u r e to levels at which skin vessels will dilate, will not lo we r muscle t e m p e ra t u r e s to levels at which deep vessel c o n st r ic tio n is inhibited. O u r results f u r t h e r suggest t h a t to achieve dila tat io n of vessels it is not necessary to a pp ly icepacks for long er th an 8 -10 minutes. References A b r a m s o n D D , K a h n A, Rejal H, et al. (1958). Re lat ionship between a r a ng e o f tissue te m p e ra t u re s a n d local oxy­ gen up t ak e in the h u m a n fo re a rm . J ournal o f Clinical Investigation. 37, 1031-1038. A ll w o o d M J , Bu rr y HS (1954). T h e effect of local t e m p e ra t u re on b lo od flow in the h u m a n foot. Journal o f Physiology. 124, 345-357. Bar cro ft H. E d h o lm O G (1943). T h e effect of t e m p e r a t u r e on b l oo d flow a n d deep t e m p e r a t u r e in the h u m a n fore ­ a rm . Journal o f P hysiology. 102, 5-20. Bi er m a n W (1955). T h e r a p e u t i c use o f cold. ./. A m . Med. A sso., 157, 1189-1192. K ni ght K L , L o nd er e e BR (1980). C o m p a r i s o n of b l o o d flow in the ank le o f un i n ju r e d sub jects d u r i n g t he r a p eu ti c a pp lic at io ns of heat, cold a n d exercise. M edicine and Science in S p o rts a n d Exercise. 12, 76-80. L ai n g D R , Dailey D R , K i rk J A (1973). Ice th er a p y in soft tissue injuries. N Z Med. J., 78, 155-158. S c a n do la M, Pezzin G (1978). T h e low tem p e ra t u r e mec han ic al rela xati on o f elastin. II. T h e solva ted p r o ­ tein. B iopolym ers. 17, 213-223. V a n h o u t te PM , V er beu re n T J , W e b b RC (1981). Local m o d u la t io n of a dr ene rg ic n eu ro eff ect or in te ra c tio n in the b l o o d vessel wall. P hysiological Review. 61, 151-247. THE MEASUREMENT OF PAIN - A BRIEF REVIEW C. A. L I G G I N S , M . C .S .P .. H.T.. D IP . T.P.* S um m ary P hysiotherapists are now m easuring pain when they assess their patients. Pain has been considered to be unm easurable by some, but a num ber o f subjective and objective m e thods have been devised. S u bjective m ethods appear to be more sa tisfa cto ry than objective m ethods. S e ve ra l m ethods o f subjective m easurem ent are reviewed. S tu d ie s suggest that the N um erical R a tin g Scale (N .R .S .) m a y be an appropriate subjective scale f o r general use. S everal m ethods o f measuring pain r e lie f are also reviewed. P atients te n d to express them selves m ore in term s o f pain r e lie f than in term s o f pain m easurem ent. The principles o f the S ig n a l D etection Theory f o r quantification o f pain are outlined. IN T R O D U C T IO N O n e of the mo st i m p o r t a n t d e v e l o p m e n t s in the p h y s i o t h e r a p y p ro fes sio n d u r i n g the last few years has been th e in creasing em ph a si s on g o o d assess men t pr io r to ph y si o t h er a p eu t i c inter ven ti on. M e a s u re m e n t is the essence o f scientific m e t h o d a nd d u r i n g their assess men t o f pa tien ts, p hy sio th era pi sts ro utine ly m ea su re such things as muscle s t r e n g th a n d jo in t m o tio n , b u t until recent times it has no t been usual for them t o mea sur e the m a j o r a c c o m p a n i m e n t o f so m any of the c on d it i o n s they tr eat , name ly pain. A c c o r d i n g to H u s k is so n (1974) “ pa in c a n n o t be said to hav e been relieved unless pa in o r p ain relief has been directly m e a s u r e d ” . T h u s the q u e st io n o f the feasibility of pain m ea su r e m e nt mu st be raised. Pain is an a b s t r a c t i o n a nd ther ef ore has been c on sid ere d by m an y to be u n m ea su ra b le . S e n i o r L e c t u r e r , S u b - D e p a r t m e n t o f P h y s i o t h e r a p y , Univ ers ity o f D u rb a n - W e st v i ll e Received 30 Ap ril 1982. O psom m ing F iosioterapeute m eet nou p yn wanneer hulle hut pasiente evalueer. Pyn is deur som m ige as onm eetbaar beskou, m a a r ’n a antal su bjektiew e en o b jektiew e m etodes is ontwerp. S u b je k tie w e m etodes b ly k m eer bevredigend te wees as objek tie w e m etodes. Verskeie m etodes van su bjektiew e m eting w ord hersien. S tu d ie s stel voor d at die N um eriese W aardebepalingskaal (N um erical R a tin g Scale, N .R .S .) 'n g e s k ik te su b jektiew e sk a a l vir a lgem em e g ebruik m ag wees. Verskeie m e todes om p yn ve rlig tin g !e m e et w o r d o o k hersien. P asiente is geneig om liu lse lf eerder in term e van pynverligting as p y n m a a t uit te druk. Die beginsels van die Sein V asstellingsteorie (S ig n a l D etection Theory) van pyn kw a n tifiserin g w ord geskets. H o w ev e r , psychologists have been c o n f r o n t e d by s im ila r '' p r o b l em s relating to the m e a su r e m e n t o f pe rsona lity, d e pr es s io n a n d sleep, a n d they hav e c o p ed with this since the early pa rt o f the century. W hen m e a su r e m e n t o f pa in is being c o nsi der ed , a dist inctio n must be m a d e between ex per im en tal a n d clinical pain. M e a s u r e m e n t o f pa in in the l a b o r a t o r y is relatively easy. Specific a n d g r a d e d stimuli can be used a n d the r esp ons es analysed. It is thu s possible to o bt ai n a large d e g r e e o f s a m e n e s s in e x p e r i m e n t s a n d re la ti v e ly r e p ro du c ib le results can be o b t a i n e d (Ro se n, 1977). Ho w ev e r, with clinical pain the n a tu r e o f the stim ul us may no t be ob vi ou s a n d in some cases pain levels give no ind ica tion o f the severity of the disease. In a d d it i o n pain may be m od ifi ed by m a n y be ha v i o u r a l fa ctors ( Hu sk is so n , 1974). The p r o b l e m o f pa in m e a s u r e m e n t has been a p p r o a c h e d basically in tw o ways. T he most used is the “ subje cti ve ” m e t h o d in which the pa tie n t is a sk e d to re p or t his pain experience directly. A lt ern ati ve ly a n “ obj ect ive ” o r indirect m ea su re (visible o r non -v e rb a l) can be used if there is a re la tio n sh ip betw een the m ea su re a n d relief o f p a in (Rosen, 1977). 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. )