- Email: [email protected]
PULMONARY DIFFUSION CAPACITY
679
caused by chloramphenicol. ] McElfresh and Huang conclude that methicillin " should be considered capable of
suppressing figures,
the
the bone marrow "-although, on their rate of recovery is that of a resilient, not a
depressed, marrow. Against this
neutropenia should be set the absence of any other report incriminating the drug. Nevertheless, despite general awareness of their possibility, toxic effects on the marrow are often tardily noticed, especially where idiosyncrasy may be a factor. Chloramphenicol had been widely used for two years one case
of
before its effect on the marrow was observed. The case reported by McElfresh and Huang may or may not be the
prototype; but it certainly carries a hint of danger, and should once again alert clinicians and clinical pathologists the need for reliable
to
therapy with any
new
hasmatological checks during drug.
LONDON’S WATER
THE biennial scientific report of the Metropolitan Water to be mistaken for a work of voluptuous but it a good deal more of general interest contains fiction, than might be expected. 12 The technical details of the recent improvements in the methods of enumerating coliform bacteria in water are in the main for the experts only, but they may be of some interest to those who ponder on the rationale of scientific method. The need is for a method which will be cheap and will not call for staff of outstanding skill. It must within 48 hours give an answer which will be reliable enough to justify positive action. Absolute accuracy may be unobtainable, but comparative accuracy between successive samples is essential. Estimation of the numbers by dilution methods in nutrient media yields no more than an approximation to the truth, but within its statistical limits it gives reproducible results. Since this method was introduced there have been many modifications in detail, but it remains costly in time and space. Enumeration by direct counting on the membrane filter has not so far been popular in Great Britain, but the work done in the M.W.B. laboratories suggests that we are falling behind the times. Another novelty discussed in this report is the rapid detection of bacteria by the use" of radio-isotopes, which gives some promise as a test of absolute purity ". The biological problems of the Board are largely those presented by the growth of algx, and the report includes a short note on some experiments in progress on control by upsetting mechanically the thermal stratification of reservoirs. Because three establishments of the Atomic Energy Authority discharge some radioactive waste into the Thames (which is now the main source of London’s drinking-water) routine tests for beta activity are performed weekly. The figures found agree closely with those from other sources and have not yet given reason for alarm.
Board is not likely
Most water authorities take
pains to
see
that
they do not
engage carriers of typhoid fever as members of their staff. The M.W.B. goes further and makes certain that those who have been off duty because of diarrhoeal disease are
longer infectious when they return. We would like know how this works in practice. Despite the employment of a good deal of immigrant labour, no carriers have
no
to
11. Rubin,
D., Weisberger, A. S., Botti, R. E., Storaasli, J. P. J. clin. Invest. 1958, 37, 1286. 12. Metropolitan Water Board. 39th report on the results of the bacteriological, chemical, and biological examination of London waters for the years 1959-60. E. WINDLE TAYLOR, M.A., M.D., D.P.H., M.W.B., Rosebery Avenue, London E.C.1. Pp. 122. 21s.
found; but those who harbour ova of roundworms, whipworms, or hookworms are not uncommon. We doubt whether any of these present a danger in this climate. Only one man was found to harbour Entamaeba histolytica. Failing a more rational explanation, it has not been been
unknown for members of our profession to blame the hardness of the water for hardening of the arteries or a stone in the bladder. There is, in fact, increasing evidence that in Great Britain, as in the U.S.A. and Japan, there is a negative correlation between cardiovascular disease and hard water.13 As for bladder stones, in children at any rate they have become rare in London during a long period when the hardness of the public water-supply has remained unchanged. Of the less specific complaints (their number rises with hot summers and a shortage of water) the four main ones concern taste and smell, rust or grit, coloured water, and ill-health. The water is often blamed for diarrhoea or sore throat and sometimes for diseases of the skin or kidneys. In every instance which was investigated during 1959-60 the water was up to standard. About twenty exotic tastes were the subject of complaints, and of these the commonest was the very real musty taste acquired by water in the cold pipes when it is warmed. A rise to 20°C is enough and is usually caused by the combination of a high atmospheric temperature and heat from hot pipes alongside. To some a taste of chlorine is a red rag: others do not notice it or remember when they had the choice of hyperchlorinated water or rapid desiccation. Up-to-date water undertakings now use chlorinating plant which can be adjusted to extremely fine limits; but when changes are being made, especially in the quality of the raw water, there is always a risk of a whiff of the gas escaping which will drive some consumers to outraged complaint. Perhaps the M.W.B. (and other undertakings) might give more prominence to the fact that, while some complaints are justified, the cause of the trouble is as often as not on the consumer’s premises for which the supplier has no responsibility. Cisterns have been known to harbour a most varied flora and fauna, alive and dead, quite apart from such things as the family silver (safely hidden) or a toy boat. These are but a few selections from a report which shows how much we take for granted when we draw a glass of pure water from the tap. The bold undertaker who dug the New River in 1613-still a source of supply to the M.W.B.-would understand little of it but would applaud the search for perfection in every department. PULMONARY DIFFUSION CAPACITY
MEASUREMENT of the diffusion capacity (DL) of the lung-i.e., the alveolar-capillary gas exchange-is now an important test of lung function. There are two carbonmonoxide methods of conducting the test. The first of these is the " steady-state method 14; DL can be estimated during exercise (which provides a valuable measure of physiological reserve), and the necessary calculations are simple. The second is the " single-breath method.15 The usefulness of the single-breath test as a routine investigation has been studied by three groups in the "
"
U.S.A.16-18 Burrows
et
al.16 conclude that
a
low DL is
Morris, J. N., Lancet, 1961, i, 860. W. J. clin. Invest. 1954, Filley, G. F., 33, 530. 15. Forster, R. E. Physiol. Rev. 1957, 37, 391. 16. Burrows, B., Kasik, J. E., Niden, A. H., Barclay, W. R. Amer. Rev. resp. Dis. 1961, 84, 789. 17. Dietiker, F., Lester, W., Gottlieb, R., Burrows, B. ibid. p. 807. 18. Williams, Jr., M. H., Seriff, N. S., Akyol, T., Yoo, O. H. ibid. p. 814. 13. 14.
Crawford, M. D., Heady, J. A. MacIntosh, D. J., Wright, G.
680
completely non-specific; it was found in all the cardiopulmonary disorders studied where lung-volume was reduced. In 7 cases where pulmonary blood-flow was high and blood was shunted from left to right, the measured DL
higher than that predicted. Possibly, therefore, the be of some use in the diagnosis of left-to-right shunt in congenital heart-disease. Dietiker et al.,17 analysing the results in 221 patients with pulmonary tuberculosis, found that in many DL was low; but much of the reduction could be accounted for by loss of lungvolume, and the test added little to what was already known from measuring the lung-volume. Williams et al.18 describe a method for investigating DL at the bedside, and hope that this will provide a useful indication of progress in acute pulmonary tuberculosis. They found a close association between impairment of diffusion and the extent of X-ray abnormality, whereas the reduction of vital capacity correlated poorly with the X-ray changes. The impairment of diffusion seemed, however, to be greater than the X-ray shadowing might have suggested; and the DL is possibly a more sensitive index of tuberculous involvement than is an X-ray. Pulmonary diffusion capacity is impaired where the alveolar membrane is thickened (sarcoidosis, diffuse interstitial fibrosis), where its area is reduced (emphysema), or where the total lung-volume is diminished. Other ventilatory tests-estimates of vital capacity, forced vital capacity, and the one-second forced expiratory volumemust be used to distinguish between these conditions. By itself the DL is of small diagnostic value; but, in conjunction with these other tests, it may indicate the disease responsible for the functional impairment. Serial estimates of DL may also be of value in assessing response to treatment-for instance, where sarcoidosis or diffuse interstitial was
test may
fibrosis is treated with corticosteroids. Finally, the DL is of some prognostic value in emphysema and interstitial fibrosis; very low values in these conditions are ominous. 11 20
TALIPES
EQUINOVARUS
CONGENITAL deformities of the foot can readily be recognised at birth, and few patients with club foot now escape treatment within the first few days of life. When the condition is mild and can be corrected with ease,
repeated simple manipulation during the early postnatal period may be all this is required. Where the deformity is more severe, each manipulation must be followed by the application of a retaining splint, or by immobilisation of the foot in suitable strapping or plaster; ideally, this treatment should be continued until active eversion by the child can maintain the foot in the corrected position. Relapse is relatively uncommon when the deformity has been easily corrected and maintained in an over-corrected position by a splint. But manipulation may produce spurious correction, and the forefoot is often plantigrade when the heel is still deformed. It is chastening to discover how often a clinically well-corrected foot presents, in lateral radiographs of the heel, an os calcis in pronounced equinus. If this tendency is recognised early, then, at open operation, the tendo Achillis may be elongated and the posterior capsule of the ankle-joint released; there is much to be said for carrying out this simple procedure early in any severely deformed foot. The term " club foot " includes conditions ranging 19. 20.
Bates, D. V., Knott, J. M. S., Christie, R. V. Quart. J. Med. 1956,25, 137. MacNamara, J., Prime, F. J., Sinclair, J. D. Thorax, 1959, 14, 166.
from a mild postural defect, which can be corrected at to the severe fixed deformity of arthrogryposis. Between these two extremes lie defects of differing severity, some of which are held (on very slender grounds) to be part of a localised muscle dysplasia. With such a common disorder, it is surprising that there is no general agreement on the nature of the defect. Brockman r says that the essential disturbance is medial dislocation of the navicular on the talus; and Elmslie2 describes it as primarily of the midtarsal joint, with inward displacement of the navicular and cuboid and rotation of the os calcis. Such a deformity could be produced by the tibialis posterior, and Bost et a1.3 have suggested that contracture of the fibrous insertion of this muscle is one of the fundamental lesions. If this is so, it is nevertheless true that simple division of the tibialis posterior will not correct the condition; even in the newborn, adaptive changes have already occurred in the bones and joints. The foot which is relapsing after treatment can often be corrected by wedging with serial plasters 4 ; but, even if correction is once more achieved, it may not be permanent. At this stage tendon transfer is often of value, and Singer 5 has shown that transfer of tibialis posterior through the interosseous membrane to the dorsum of the foot is much better than the more traditional transfer of tibialis anterior. Indeed, the relapse-rate after the latter operation is so high," and the secondary deformities it may produce are so disabling, that it is doubtful whether the tibialis anterior should ever be transplanted in a club foot. Correction by serial plasters is time-consuming and often ineffective, and a more rapid and certain correction can sometimes be obtained by open operation. A normal foot rarely results from release of all the shortened structures on the medial side of the foot, with widespread open division of joint capsules. Evansnow supplements this procedure with corrective excision of the calcaneocuboid joint to shorten and correct the lateral segment. In any method of correction there is a temptation to use the forefoot as a lever, and insertion of an os calcis pin may sometimes overcome the resulting tendency to false correction. The varus deformity of the heel may also be eliminated by the calcaneal osteotomy described by Dwyer 9; in this, a tibial wedge is inserted into the inner aspect of the divided os calcis, to maintain the true position. The number of procedures which are currently used to correct a relapsing club foot indicates both the magnitude of the problem and the failure of any one method to yield uniformly good results. Temporary improvement in foot posture is readily produced at the expense of joint mobility, and many surgeons prefer to wait until the child is old enough for a triple arthrodesis. Benyi 10 has shown how Lambrindi’s operation can be extended-by excision of the navicular and most of the cuboid-to correct the most severe of deformities. On an earlier page of this issue Mr. Young describes a case of Sir William Macewen’s, treated fifty years ago by astragalectomy. It is because such long-term reviews are few and far between that the assessment of all orthopaedic procedures in children is so difficult. 1. 2.
3. 4. 5. 6. 7. 8. 9. 10.
Brockman, E. P. Congenital Club Foot. Bristol, 1930. Elmslie, R. C. J. orthop. Surg. 1920, 2, 669. Bost, F. C., Schottstaedt, E. R., Larsen, L. J. J. Bone Jt Surg. 1960, 42A, 151. Kite, J. H. Sth. med. J. 1930, 23, 337. Singer, M. J. Bone Jt Surg. 1961, 43B, 717. Singer, M., Fripp, A. T. ibid. 1958, 40B, 252. Evans, D. ibid. 1961, 43B, 722. Morita, S. ibid. 1962, 44A, 149. Dwyer, F. C. ibid. 44B, 218. Bényi, P. ibid. 1960, 333.
caused by chloramphenicol. ] McElfresh and Huang conclude that methicillin " should be considered capable of
suppressing figures,
the
the bone marrow "-although, on their rate of recovery is that of a resilient, not a
depressed, marrow. Against this
neutropenia should be set the absence of any other report incriminating the drug. Nevertheless, despite general awareness of their possibility, toxic effects on the marrow are often tardily noticed, especially where idiosyncrasy may be a factor. Chloramphenicol had been widely used for two years one case
of
before its effect on the marrow was observed. The case reported by McElfresh and Huang may or may not be the
prototype; but it certainly carries a hint of danger, and should once again alert clinicians and clinical pathologists the need for reliable
to
therapy with any
new
hasmatological checks during drug.
LONDON’S WATER
THE biennial scientific report of the Metropolitan Water to be mistaken for a work of voluptuous but it a good deal more of general interest contains fiction, than might be expected. 12 The technical details of the recent improvements in the methods of enumerating coliform bacteria in water are in the main for the experts only, but they may be of some interest to those who ponder on the rationale of scientific method. The need is for a method which will be cheap and will not call for staff of outstanding skill. It must within 48 hours give an answer which will be reliable enough to justify positive action. Absolute accuracy may be unobtainable, but comparative accuracy between successive samples is essential. Estimation of the numbers by dilution methods in nutrient media yields no more than an approximation to the truth, but within its statistical limits it gives reproducible results. Since this method was introduced there have been many modifications in detail, but it remains costly in time and space. Enumeration by direct counting on the membrane filter has not so far been popular in Great Britain, but the work done in the M.W.B. laboratories suggests that we are falling behind the times. Another novelty discussed in this report is the rapid detection of bacteria by the use" of radio-isotopes, which gives some promise as a test of absolute purity ". The biological problems of the Board are largely those presented by the growth of algx, and the report includes a short note on some experiments in progress on control by upsetting mechanically the thermal stratification of reservoirs. Because three establishments of the Atomic Energy Authority discharge some radioactive waste into the Thames (which is now the main source of London’s drinking-water) routine tests for beta activity are performed weekly. The figures found agree closely with those from other sources and have not yet given reason for alarm.
Board is not likely
Most water authorities take
pains to
see
that
they do not
engage carriers of typhoid fever as members of their staff. The M.W.B. goes further and makes certain that those who have been off duty because of diarrhoeal disease are
longer infectious when they return. We would like know how this works in practice. Despite the employment of a good deal of immigrant labour, no carriers have
no
to
11. Rubin,
D., Weisberger, A. S., Botti, R. E., Storaasli, J. P. J. clin. Invest. 1958, 37, 1286. 12. Metropolitan Water Board. 39th report on the results of the bacteriological, chemical, and biological examination of London waters for the years 1959-60. E. WINDLE TAYLOR, M.A., M.D., D.P.H., M.W.B., Rosebery Avenue, London E.C.1. Pp. 122. 21s.
found; but those who harbour ova of roundworms, whipworms, or hookworms are not uncommon. We doubt whether any of these present a danger in this climate. Only one man was found to harbour Entamaeba histolytica. Failing a more rational explanation, it has not been been
unknown for members of our profession to blame the hardness of the water for hardening of the arteries or a stone in the bladder. There is, in fact, increasing evidence that in Great Britain, as in the U.S.A. and Japan, there is a negative correlation between cardiovascular disease and hard water.13 As for bladder stones, in children at any rate they have become rare in London during a long period when the hardness of the public water-supply has remained unchanged. Of the less specific complaints (their number rises with hot summers and a shortage of water) the four main ones concern taste and smell, rust or grit, coloured water, and ill-health. The water is often blamed for diarrhoea or sore throat and sometimes for diseases of the skin or kidneys. In every instance which was investigated during 1959-60 the water was up to standard. About twenty exotic tastes were the subject of complaints, and of these the commonest was the very real musty taste acquired by water in the cold pipes when it is warmed. A rise to 20°C is enough and is usually caused by the combination of a high atmospheric temperature and heat from hot pipes alongside. To some a taste of chlorine is a red rag: others do not notice it or remember when they had the choice of hyperchlorinated water or rapid desiccation. Up-to-date water undertakings now use chlorinating plant which can be adjusted to extremely fine limits; but when changes are being made, especially in the quality of the raw water, there is always a risk of a whiff of the gas escaping which will drive some consumers to outraged complaint. Perhaps the M.W.B. (and other undertakings) might give more prominence to the fact that, while some complaints are justified, the cause of the trouble is as often as not on the consumer’s premises for which the supplier has no responsibility. Cisterns have been known to harbour a most varied flora and fauna, alive and dead, quite apart from such things as the family silver (safely hidden) or a toy boat. These are but a few selections from a report which shows how much we take for granted when we draw a glass of pure water from the tap. The bold undertaker who dug the New River in 1613-still a source of supply to the M.W.B.-would understand little of it but would applaud the search for perfection in every department. PULMONARY DIFFUSION CAPACITY
MEASUREMENT of the diffusion capacity (DL) of the lung-i.e., the alveolar-capillary gas exchange-is now an important test of lung function. There are two carbonmonoxide methods of conducting the test. The first of these is the " steady-state method 14; DL can be estimated during exercise (which provides a valuable measure of physiological reserve), and the necessary calculations are simple. The second is the " single-breath method.15 The usefulness of the single-breath test as a routine investigation has been studied by three groups in the "
"
U.S.A.16-18 Burrows
et
al.16 conclude that
a
low DL is
Morris, J. N., Lancet, 1961, i, 860. W. J. clin. Invest. 1954, Filley, G. F., 33, 530. 15. Forster, R. E. Physiol. Rev. 1957, 37, 391. 16. Burrows, B., Kasik, J. E., Niden, A. H., Barclay, W. R. Amer. Rev. resp. Dis. 1961, 84, 789. 17. Dietiker, F., Lester, W., Gottlieb, R., Burrows, B. ibid. p. 807. 18. Williams, Jr., M. H., Seriff, N. S., Akyol, T., Yoo, O. H. ibid. p. 814. 13. 14.
Crawford, M. D., Heady, J. A. MacIntosh, D. J., Wright, G.
680
completely non-specific; it was found in all the cardiopulmonary disorders studied where lung-volume was reduced. In 7 cases where pulmonary blood-flow was high and blood was shunted from left to right, the measured DL
higher than that predicted. Possibly, therefore, the be of some use in the diagnosis of left-to-right shunt in congenital heart-disease. Dietiker et al.,17 analysing the results in 221 patients with pulmonary tuberculosis, found that in many DL was low; but much of the reduction could be accounted for by loss of lungvolume, and the test added little to what was already known from measuring the lung-volume. Williams et al.18 describe a method for investigating DL at the bedside, and hope that this will provide a useful indication of progress in acute pulmonary tuberculosis. They found a close association between impairment of diffusion and the extent of X-ray abnormality, whereas the reduction of vital capacity correlated poorly with the X-ray changes. The impairment of diffusion seemed, however, to be greater than the X-ray shadowing might have suggested; and the DL is possibly a more sensitive index of tuberculous involvement than is an X-ray. Pulmonary diffusion capacity is impaired where the alveolar membrane is thickened (sarcoidosis, diffuse interstitial fibrosis), where its area is reduced (emphysema), or where the total lung-volume is diminished. Other ventilatory tests-estimates of vital capacity, forced vital capacity, and the one-second forced expiratory volumemust be used to distinguish between these conditions. By itself the DL is of small diagnostic value; but, in conjunction with these other tests, it may indicate the disease responsible for the functional impairment. Serial estimates of DL may also be of value in assessing response to treatment-for instance, where sarcoidosis or diffuse interstitial was
test may
fibrosis is treated with corticosteroids. Finally, the DL is of some prognostic value in emphysema and interstitial fibrosis; very low values in these conditions are ominous. 11 20
TALIPES
EQUINOVARUS
CONGENITAL deformities of the foot can readily be recognised at birth, and few patients with club foot now escape treatment within the first few days of life. When the condition is mild and can be corrected with ease,
repeated simple manipulation during the early postnatal period may be all this is required. Where the deformity is more severe, each manipulation must be followed by the application of a retaining splint, or by immobilisation of the foot in suitable strapping or plaster; ideally, this treatment should be continued until active eversion by the child can maintain the foot in the corrected position. Relapse is relatively uncommon when the deformity has been easily corrected and maintained in an over-corrected position by a splint. But manipulation may produce spurious correction, and the forefoot is often plantigrade when the heel is still deformed. It is chastening to discover how often a clinically well-corrected foot presents, in lateral radiographs of the heel, an os calcis in pronounced equinus. If this tendency is recognised early, then, at open operation, the tendo Achillis may be elongated and the posterior capsule of the ankle-joint released; there is much to be said for carrying out this simple procedure early in any severely deformed foot. The term " club foot " includes conditions ranging 19. 20.
Bates, D. V., Knott, J. M. S., Christie, R. V. Quart. J. Med. 1956,25, 137. MacNamara, J., Prime, F. J., Sinclair, J. D. Thorax, 1959, 14, 166.
from a mild postural defect, which can be corrected at to the severe fixed deformity of arthrogryposis. Between these two extremes lie defects of differing severity, some of which are held (on very slender grounds) to be part of a localised muscle dysplasia. With such a common disorder, it is surprising that there is no general agreement on the nature of the defect. Brockman r says that the essential disturbance is medial dislocation of the navicular on the talus; and Elmslie2 describes it as primarily of the midtarsal joint, with inward displacement of the navicular and cuboid and rotation of the os calcis. Such a deformity could be produced by the tibialis posterior, and Bost et a1.3 have suggested that contracture of the fibrous insertion of this muscle is one of the fundamental lesions. If this is so, it is nevertheless true that simple division of the tibialis posterior will not correct the condition; even in the newborn, adaptive changes have already occurred in the bones and joints. The foot which is relapsing after treatment can often be corrected by wedging with serial plasters 4 ; but, even if correction is once more achieved, it may not be permanent. At this stage tendon transfer is often of value, and Singer 5 has shown that transfer of tibialis posterior through the interosseous membrane to the dorsum of the foot is much better than the more traditional transfer of tibialis anterior. Indeed, the relapse-rate after the latter operation is so high," and the secondary deformities it may produce are so disabling, that it is doubtful whether the tibialis anterior should ever be transplanted in a club foot. Correction by serial plasters is time-consuming and often ineffective, and a more rapid and certain correction can sometimes be obtained by open operation. A normal foot rarely results from release of all the shortened structures on the medial side of the foot, with widespread open division of joint capsules. Evansnow supplements this procedure with corrective excision of the calcaneocuboid joint to shorten and correct the lateral segment. In any method of correction there is a temptation to use the forefoot as a lever, and insertion of an os calcis pin may sometimes overcome the resulting tendency to false correction. The varus deformity of the heel may also be eliminated by the calcaneal osteotomy described by Dwyer 9; in this, a tibial wedge is inserted into the inner aspect of the divided os calcis, to maintain the true position. The number of procedures which are currently used to correct a relapsing club foot indicates both the magnitude of the problem and the failure of any one method to yield uniformly good results. Temporary improvement in foot posture is readily produced at the expense of joint mobility, and many surgeons prefer to wait until the child is old enough for a triple arthrodesis. Benyi 10 has shown how Lambrindi’s operation can be extended-by excision of the navicular and most of the cuboid-to correct the most severe of deformities. On an earlier page of this issue Mr. Young describes a case of Sir William Macewen’s, treated fifty years ago by astragalectomy. It is because such long-term reviews are few and far between that the assessment of all orthopaedic procedures in children is so difficult. 1. 2.
3. 4. 5. 6. 7. 8. 9. 10.
Brockman, E. P. Congenital Club Foot. Bristol, 1930. Elmslie, R. C. J. orthop. Surg. 1920, 2, 669. Bost, F. C., Schottstaedt, E. R., Larsen, L. J. J. Bone Jt Surg. 1960, 42A, 151. Kite, J. H. Sth. med. J. 1930, 23, 337. Singer, M. J. Bone Jt Surg. 1961, 43B, 717. Singer, M., Fripp, A. T. ibid. 1958, 40B, 252. Evans, D. ibid. 1961, 43B, 722. Morita, S. ibid. 1962, 44A, 149. Dwyer, F. C. ibid. 44B, 218. Bényi, P. ibid. 1960, 333.