1144 Power-operated Prostheses SPLINTS and appliances have been used for centuries to assist people who have lost a limb or are paralysed, but it is only quite lately that external sources of power have been harnessed to help the disabled. The various forms of mechanical wheel-chairs, motorised tricycles, and motor-cars for paraplegics and patients with bilateral amputations are by now familiar devices. Less well known is the ’ Possum’, or patient-operated selector mechanism control, for the severely disabled, which was developed at Stoke Mandeville by the electromechanical laboratory for aids to the disabled. A patient who is completely paralysed in his arms, trunk, and legs can select any of various functions by blowing or sucking through a small plastic tube. By this means he can control a bell, light, radio, microfilm projector, heat, curtains, fan, telephone, television, bed-tilt, page- turning, and a typewriter. The basis of such aids is that the patient initiates an action which serves as a signal or stimulus to make a machine perform the required move- ment. Such movements may be programmed (i.e., fol- lowing a set sequence unless or until the movement is stopped) or they may be guided (i.e., subject to modifica- tion according to visual, auditory, or proprioceptive sensations). In 1955 BATTYE et al.1 described a prototype upper- arm prosthesis in which a split hook was activated by an electric motor which was controlled by the amplification of action-potentials picked up by skin electrodes from a patient’s muscles. In the original model the skin elec- trodes were held in place by a suction pump, but the amplifier was comparatively bulky and the source of power was the " mains " electricity supply. Since then, work on power-operated devices has proceeded in many countries. In Germany and the U.S.A. upper-arm prostheses, activated by releasing carbon-dioxide gas under pressure, have been highly developed with con- siderable sophistication in control. In this country A. H. BOTTOMLEY, of St. Thomas’s Hospital, London, has designed and produced a bioelectric limb 2; and other centres in this country, the U.S.A., Canada, Italy, and Yugoslavia are working on similar lines. In the U.S.S.R. a bioelectric upper-limb prosthesis has been in produc- tion for some years, and about 150 patients have been fitted: these have been mainly patients with below- elbow amputation, bilateral in some. The apparatus has proved reliable. The first model catered only for control of simple grasping and ungrasping movements with the digits. Subsequent models have incorporated pronation- supination movements, and experimental work is pro- ceeding with models which control wrist flexion as well. Of course the signals need not derive from the muscles of the affected arm or stump: a muscle in a remote part of the body can be used as a signal, and direct amplifica- tion is not the only way in which such a signal could be converted into mechanical movement. Perfect control of a power limb will require an element of " propriocep- 1. Battye, C. K., Nightingale, A., Whillis, J. J. Bone Jt. Surg. 1955, 37b, 506. 2. Bottomley, A. H., Cowell, T. K. New Scientist, March 12, 1964, p 668. tion " or-to use a more modern term, a " feed-back." In the United States much work has been done with programmed aids : the patient turns on a given pro- gramme, according to which the prosthesis performs stereotyped movements-e.g., picking up an object and conveying it to the mouth. The stimulus might well be wrinkling of the forehead or even an auditory or mouth signal, or, as in the possum device, a blow and suck signal. These developments conjure up exciting possibilities, but clearly further progress depends on enlisting the aid of physicists and engineers; very few medical men know enough of engineering and physics to design mechanical prostheses themselves. The cooperation of different disciplines always present problems, not the least of which is the career prospects of those involved. Whether such cooperation will be best obtained by setting up special institutes as in the U.S.S.R., or in the research laboratories of large industrial concerns, or at a univer- sity or technical college, is still uncertain. It is hearten- ing that the Ministry of Health’s advisory committee on prosthesis includes industrialists, physicists, and engineers. From them we can expect much. Systems of Medicine INTELLECTUAL freedom, like political freedom, is for many people a burden; and, even when established, it seldom lasts very long. In periods of freedom, great minds speculate on fundamentals and devise systems of knowledge. The more successful these systems are, however, the sooner do weaker minds accept them as dogma; and the longer they persist to pervert observa- tion and stifle opinion. HIPPOCRATES worked in splendid freedom : and so did ARISTOTLE. But things were already different for GALEN, great experimenter though he was. Losing the restless inquiring approach of the masters, their successors ended by accepting their teaching as a body of mystically revealed theory which the facts must be made to fit. All this is familiar; and so is the long persistence of Aristotelian concepts in more and more debased forms throughout the Middle Ages, and the breaking of the mould by the great minds of the Renaissance. What is less often mentioned is the geographical distances over which these concepts spread, and the continuance of ARISTOTLE’S physiological theories to the present day. After the fall of Constantinople, Greek ideas were preserved and somewhat extended by the Arabs : indeed some original Greek works of later date are known only in Arabic versions. But Greek ideas also spread to the Indian subcontinent, where they are still in fact the basis on which many practitioners work-practitioners who, because our science has overtaken them, would no longer be accepted as doctors in any Western country. In Pakistan, which is primarily Muslim, the traditional system of medicine is known as Unani Tibb. In Hindu India, it is the better-known Ayurveda, and has latterly gained increasing importance because it receives so much official encouragement. In well-equipped , Ayurvedic hospitals and schools the students nowadays , are smart young men with Westernised general education;
Transcript
1144
Power-operated ProsthesesSPLINTS and appliances have been used for centuries
to assist people who have lost a limb or are paralysed,but it is only quite lately that external sources of powerhave been harnessed to help the disabled. The variousforms of mechanical wheel-chairs, motorised tricycles,and motor-cars for paraplegics and patients with bilateralamputations are by now familiar devices. Less wellknown is the ’ Possum’, or patient-operated selectormechanism control, for the severely disabled, which wasdeveloped at Stoke Mandeville by the electromechanicallaboratory for aids to the disabled. A patient who iscompletely paralysed in his arms, trunk, and legs canselect any of various functions by blowing or suckingthrough a small plastic tube. By this means he cancontrol a bell, light, radio, microfilm projector, heat,curtains, fan, telephone, television, bed-tilt, page-turning, and a typewriter. The basis of such aids is thatthe patient initiates an action which serves as a signal orstimulus to make a machine perform the required move-ment. Such movements may be programmed (i.e., fol-lowing a set sequence unless or until the movement isstopped) or they may be guided (i.e., subject to modifica-tion according to visual, auditory, or proprioceptivesensations).
In 1955 BATTYE et al.1 described a prototype upper-arm prosthesis in which a split hook was activated by anelectric motor which was controlled by the amplificationof action-potentials picked up by skin electrodes from apatient’s muscles. In the original model the skin elec-trodes were held in place by a suction pump, but theamplifier was comparatively bulky and the source ofpower was the " mains " electricity supply. Since then,work on power-operated devices has proceeded in manycountries. In Germany and the U.S.A. upper-armprostheses, activated by releasing carbon-dioxide gasunder pressure, have been highly developed with con-siderable sophistication in control. In this countryA. H. BOTTOMLEY, of St. Thomas’s Hospital, London,has designed and produced a bioelectric limb 2; and othercentres in this country, the U.S.A., Canada, Italy, andYugoslavia are working on similar lines. In the U.S.S.R.a bioelectric upper-limb prosthesis has been in produc-tion for some years, and about 150 patients have beenfitted: these have been mainly patients with below-elbow amputation, bilateral in some. The apparatus hasproved reliable. The first model catered only for controlof simple grasping and ungrasping movements with thedigits. Subsequent models have incorporated pronation-supination movements, and experimental work is pro-ceeding with models which control wrist flexion as well.Of course the signals need not derive from the musclesof the affected arm or stump: a muscle in a remote partof the body can be used as a signal, and direct amplifica-tion is not the only way in which such a signal could beconverted into mechanical movement. Perfect controlof a power limb will require an element of " propriocep-
1. Battye, C. K., Nightingale, A., Whillis, J. J. Bone Jt. Surg. 1955, 37b,506.
2. Bottomley, A. H., Cowell, T. K. New Scientist, March 12, 1964, p 668.
tion " or-to use a more modern term, a " feed-back."
In the United States much work has been done with
programmed aids : the patient turns on a given pro-gramme, according to which the prosthesis performsstereotyped movements-e.g., picking up an object andconveying it to the mouth. The stimulus might well bewrinkling of the forehead or even an auditory or mouthsignal, or, as in the possum device, a blow and suck signal.These developments conjure up exciting possibilities,
but clearly further progress depends on enlisting the aidof physicists and engineers; very few medical men knowenough of engineering and physics to design mechanicalprostheses themselves. The cooperation of differentdisciplines always present problems, not the least ofwhich is the career prospects of those involved. Whethersuch cooperation will be best obtained by setting upspecial institutes as in the U.S.S.R., or in the researchlaboratories of large industrial concerns, or at a univer-sity or technical college, is still uncertain. It is hearten-
ing that the Ministry of Health’s advisory committeeon prosthesis includes industrialists, physicists, andengineers. From them we can expect much.
Systems of MedicineINTELLECTUAL freedom, like political freedom, is for
many people a burden; and, even when established, itseldom lasts very long. In periods of freedom, greatminds speculate on fundamentals and devise systems ofknowledge. The more successful these systems are,
however, the sooner do weaker minds accept them asdogma; and the longer they persist to pervert observa-tion and stifle opinion. HIPPOCRATES worked in splendidfreedom : and so did ARISTOTLE. But things were alreadydifferent for GALEN, great experimenter though he was.Losing the restless inquiring approach of the masters,their successors ended by accepting their teaching as abody of mystically revealed theory which the facts mustbe made to fit.
All this is familiar; and so is the long persistence ofAristotelian concepts in more and more debased forms
throughout the Middle Ages, and the breaking of themould by the great minds of the Renaissance. What is lessoften mentioned is the geographical distances over whichthese concepts spread, and the continuance of ARISTOTLE’Sphysiological theories to the present day. After the fallof Constantinople, Greek ideas were preserved andsomewhat extended by the Arabs : indeed some originalGreek works of later date are known only in Arabicversions. But Greek ideas also spread to the Indiansubcontinent, where they are still in fact the basis onwhich many practitioners work-practitioners who,because our science has overtaken them, would no longerbe accepted as doctors in any Western country. InPakistan, which is primarily Muslim, the traditionalsystem of medicine is known as Unani Tibb. In HinduIndia, it is the better-known Ayurveda, and has latterlygained increasing importance because it receives so
much official encouragement. In well-equipped, Ayurvedic hospitals and schools the students nowadays,
are smart young men with Westernised general education;
1145
and the teachers are far from being the depressedvillagers that might be imagined. Indeed some of these
colleges bear the names of distinguished members of ourprofession who thus lend support to the " indigenousmedicine of their country.
Unani Tibb is the closer to ARISTOTLE, with a funda-mental doctrine of four humours based on four" elements "-hot, cold, moist, and dry. As SHAH 1
points out, the whole is hardly altered from the originalsources. Earth, air, fire, and water; bile, phlegm, blackbile, and blood; choleric, saturnine, phlegmatic, andsanguine temperaments-all are introduced into thebasic system of physiology. Moreover, the practitionerof Unani Tibb, the hakim, employs the highly respectabletheory of causality formulated by ARISTOTLE-the
theory which in fact most of us use, however outmodedit may be to specialists, just as we still rely on NEWTON’Slaws of motion. Once their fundamental postulates aregranted, both indigenous systems are rational enough:they are far from magic and witch-doctoring. Ayurveda,meaning " the science of life coupled with the art ofliving" ,2 is based on three fundamental concepts, thetridosha comprising Vata (wind), Pitta (bile) and
Kapha (phlegm), although SHASTRI 2 characterises theseas very crude translations. As in the developed Greekand Arabic systems, whether applied to medicine oralchemy, these are concepts and not actual substances:they are fundamental attributes which can be employedin different admixture to describe any phenomenon.Though the persistence of Graeco-Arabian ideas
among Muslims is not unexpected, the route by whichthey reached the Hindus is less clear. Two importantlines of connection with Grxco-Roman civilisation are
possible: one is via the north-western route opened upby ALEXANDER THE GREAT and kept open for manycenturies, while the other is the sea route utilised so
fully in later times for trade to entrepots on the Coro-mandel coast. The hakim can still refer directly to suchArabic classics as AviCENNA’s Qanoon, but the practi-tioner of Ayurveda (the " ved " to medical men) hashis own heroes, who seem to have been real people.CHARAKA was the great physician and SusRUTA the greatsurgeon. Their recorded successes in diagnosis andtreatment are impressive, and many seem advanced andreasonable to modern inspection-e.g., nerve section forintractable facial neuralgia, and laparotomy withresection of the intestine for volvulus, all by SusRUTA.As regards methods of examination, SHAH and SHASTRIboth emphasise that the systems they are describingencourage inspection and palpation, feeling the pulse,and examination of excretions, while stethoscopes arecertainly carried in Ayurvedic colleges. Treatment is
" allopathic ". With this goes a large pharmacopoeia,and it is here that much interest still lies. The remediesemployed are largely herbal, and apparently they remaincrude preparations and hence of variable action evenwhen they are pharmacologically active. But they arecheap and thus of great appeal in poor countries. The"ved" demands the standard of living of any other edu-
1. Shah, M. H. Medicus, Karachi, 1961, 22, 1.2. Shastri, M. K. J. Indian med. Prof. 1955, 2, 616.
cated man; but, compared to the practitioner of Westernmedicine, his methods and ideas are more familiar to thevast majority of ordinary people, and he does not demandlarge sums of scarce foreign currency for purified drugswith which to treat even simple ailments. The national-istic and religious implications in his training must notbe forgotten, and certainly they are not forgotten by thepoliticians; but in India and Pakistan a narrow chauvin-istic view is not taken by influential people, and methodsof diagnosis and treatment are judged by their obviousresults. The usefulness and importance of Westernmedicine are in no doubt, but Ayurveda claims to pro-duce good results and certainlv to do so cheaply. It hasthus to be taken seriously.Whether or not the " ved " or the hakim is more or
less successful than the doctor is a difficult question.Enlightened practitioners of the older systems wouldyield over many points of fact, and they are beginningto incorporate into their own work many ideas borrowedfrom Western medicine. There is no reason why" veds " or hakims should not study scientific anatomy,morbid anatomy, or radiology, nor why the facts ofphysiology or biochemistry should not be acceptable tothem. Unfortunately, however, they cannot abandon thehard core of their philosophy-a pattern into which thefacts must be made to fit and which must always obtrudeinto practical deductions. They may say that thisbasic theory is merely a philosophical vehicle for thedescription of reality; but to be chained to any onevehicle for such a purpose is a limitation to intellectualfreedom. In science, as we understand it, a theory isno more than a useful means of describing a group ofphenomena-useful in that practical deductions can bemade from it. However close to the facts such deductionsseem to be, they must never be held to confer a divinemystical truth on the theory. To make this mistake is totake the first step on a road which is all too familiar.The humoral doctrines have their advantages: thus
the current insistence on considering " the whole man "should be fulfilled if constant reference is made to them.Colonel SHAH, who is a British-trained physician, listsclassifications in which medical men of the eminence of
JUNG, KRETSCHMER, and ARTHUR HURST have arrangeddiseases in terms of derangement of the whole
personality, and he compares these classifications withthe system of AVICENNA. One must note, however, thatthe modern classifications were designed to cover
psychosomatic disease or purely psychological upsets.Few would deny the importance of
"
temperament "(in its idiomatic sense) in the causation and in the treat-ment of a peptic ulcer, but classifications successful insuch instances cannot necessarily be carried over toorganic disease such as an acute infection or a malignantgrowth.The pharmacopoeia of any system certainly deserves
investigation; for there are many examples of traditionalremedies whose value has been upheld by pharmaco-logical research. Much work has yet to be done in
evaluating such drugs; and meanwhile one can perhapsgo too far in invariably insisting on pure preparationsand a rational basis for their action before they can be
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used at all. Our own tradition, however, is right inbidding us seek the rational explanation by all relevantmeans, taking precautions to discover unwanted effectsand allow for those of accompanying impurities.
Annotations
CLINICAL TRIALS
THE techniques of clinical trials are becoming steadilymore versatile and sophisticated, but the queue of prob-lems to which they need to be applied is lengthening.Two main factors are at work: pharmaceutical researchis producing drugs that seem worth testing at a fasterrate than they can be tested; and there are not enoughtrained investigators who can do the work properly.Nothing has so far been done to remedy this situation,because it seems to be nobody’s responsibility. Neitherthe National Health Service nor the universities giveparticular encouragement to clinical trials, though per-sonal enthusiasm among clinicians in academic depart-ments, teaching hospitals, and non-teaching hospitals hasaccomplished a good deal with ad-hoc support fromvarious sources. The biggest and most impressiveentrepreneur in the field is the Medical Research Council,which pioneered large-scale controlled clinical trials.
Recently specialist associations have also carried out suchtrials; but, though these are important, they deal withonly part of the problem. Support for particular clinicaltrials is often available from the drug firms concerned,but many workers feel that this can easily lead to a
conflict of interest.On another page of this issue, Dr. Binns and Professor
Butterfield discuss the present difficulties and concludethat additional resources are probably needed-moreacademic departments, a fellowship scheme, and an
Institute of Therapeutics. Such measures could also
bridge the gulf between academic departments and
non-teaching hospitals, whose vast clinical material is atpresent contributing relatively little to the advance ofmedicine.! We strongly support the suggestion of Binnsand Butterfield that a small committee of the higheststanding should make a detailed assessment of presentresources and needs, so that soundly based andauthoritative recommendations can follow.
INHIBITION OF HÆMOPOIESIS BY OXYGEN
LONG-CONTINUED reduction of arterial P02, whetherassociated with residence at high altitudes or cardiopul-monary inadequacy, results in an unequal increase of allthe blood constituents; the most serious is a substantialrise in the red-blood cell-count. Initially this rise com-pensates partly for the lowered P02 by increasing theoxygen capacity of the blood, but it also causes increasedviscosity which can lead to tissue anoxia by reducingcardiac output. The classical method of dealing with thisstate of affairs is venesection. Unfortunately this procedureis not without risk; hence Chamberlain and Millard 2have adopted a new approach. Since the initial changeis a reduction of arterial P02 it would be logical to seekto raise this to normal. When the hypoxsemia is dueto an increase in the gradient of P02 between the alveolar1. See Lancet, 1963, i, 1039.2. Chamberlain, D. A., Millard, F. J. C. Quart. J. Med. 1963, 32, 346.
air and the arterial blood, this can be done by raising thepercentage of oxygen in the inspired air. This method-wastried some fifty years ago 4; but the work was not followedup, presumably because it is difficult to supply a high Po2over long periods. Chamberlain and Millard used thenew Venturi mask to give seven patients 35% oxygen fortwenty hours a day for periods of six weeks. In six of theseven this treatment brought about a substantial reductionin total red-cell volume, and in four there was bothsubjective and objective improvement.
It would be interesting to see whether oxygen therapycan decrease the increased plasma-volume which was acharacteristic feature of the plethora in some of the
patients with long-standing hypoxxmia studied by Shawand Simpson.5 The finding by Dill that the initialeffect of hypoxia in older subjects is a rise of blood-volumewith a fall in haemoglobin level suggests that oxygentherapy may occasionally result in a rise in haemoglobin.The method introduced by Chamberlain and Millard mayturn out to be of real value in the treatment ofpolycythsmiasecondary to hypoxia; but clearly it should meanwhile beapplied only with careful measurement of all relevantfactors.
GENETICS OF DISEASE VECTORS
MODERN control of disease vectors leans heavily oninsecticides; but the emergence of resistance and of toxichazards has stimulated a search for alternative measures.This subject was discussed in a World Health Organisationsymposium,’ in which one of the dominent themes wasthe importance of vector genetics. As a result W.H.O.
appointed a scientific group to review the relevance of thegenetics of medically important insects to their control.This group has now reported 8
It considers first the mode of inheritance of resistance
against insecticides. Though more data are always helpful,the usual pattern of inheritance seems reasonably wellestablished. As the report puts it: " These and otherstudies in the genetics of resistance have added greatlyto the understanding of field phenomena that have
developed in vector control; whether they can preciselyindicate counter-measures is problematical." There’sthe rub!
Investigations of resistance to insecticides have broughtto light the numerous lacunse in our knowledge of thegenetics of mosquitoes and other vectors. As soon as avector species is examined carefully, it is invariably foundto consist of a mosaic of races of indefinite subspecific rank,in which the various strains are commonly isolated bycytoplasmic incompatibility. Differences between theseraces may be vital in regard to vector potential, whichdepends on biological characters such as infectibility orbehaviour rather than on the morphological charactersby which species are defined in the museum.The first dividends of these researches should be
improved understanding; later they may have practicaluses. Thus, by intense breeding and release of a given
, strain in a region populated by a genetically incompatible! strain, cytoplasmic incompatibility might be applied to the; control of insects. (The report suggests applications of this idea to incompatible races of Aedes scutellaris and
3. Bence, J. Dtsch. med. Wschr. 1906, 32, 1451.4. Barcroft, J., Hunt, G. H., Dufton, D. Quart. J. Med. 1920, 13, 1795. Shaw, D. B., Simpson, T. Quart. J. Med. 1961, 30, 135.6. Dill, D. B. Fed. Proc. 1963, 22, abstr. 1761.7. See Lancet, Feb. 15, 1964, p. 373.8. Tech. Rep. Wld Hlth Org. 1964, no. 268.
