1086 a limited number of sessions, with the possibility of increasing these as she felt able and as her family got slightly older, rather than expecting her to do at least 5 sessions, and
then for her to find that this is too much for her to cope with. It would be a pity if women doctors found that they could only give the time, care, and attention which their young children need in their early years at the expense of their future career. Accident and Emergency
Department, Children’s Hospital, Western Bank, Sheffield S10 2TH.
species of animal, has a collagen which is non-antigenic all species. It is only when it is contaminated with other substances such as proteins that an antigenic response will be expected. This is well known clinically, as well as experimentally, and explains the fact that certain structures, such as the aorta, can be transplanted from one species to another, whereas the femoral artery, which has a muscular wall, cannot be so transferred. The reactions reported in this case, therefore, must be due either to the adjuvant itself or to some bacteriological or other contaminant. other
to
The General Hospital, Steelhouse Lane, Birmingham B4 6NH.
CYNTHIA M. ILLINGWORTH. ELECTRICAL HAZARDS OF DISPOSABLE MONITORING ELECTRODES
MEDICAL AUDIT
SIR,-Dr Scott and Dr Davis (March 22, p. 679) ask " why is it that the United Kingdom has been slow to launch the audit procedures so common on the other side of the Atlantic?" My answer would be: " Because the U.K. has a better sense of medical priorities than the U.S." The question really revolves around what more surely, quickly, and cheaply improves the quality of medical care: measuring " outputs " by review audits or regulating inputs " of who does what to whom ? Britain is far ahead of the U.S. in this regard. For example, some one-third of the operations in this country are performed by general practitioners or other physicians not fully trained in surgery. In British hospitals, as in our own’ better-regulated institutions, all operations are performed by qualified "
surgeons.
,
in our best medical centres compares quite favourably with the best that Britain has to offer, the overall level of surgery in Britain is higher than that of the U.S. I need not spend countless hours auditing mountains of hospital charts to validate that statement, any more than I have to road test a Rolls-Royce and a Ford to determine which is the better auto, having witnessed the materials and workmanship going into each. I am more impressed with the " input " recommendations to improve the quality of general practice cited in your editorial. These were: (1) more study to reconcile "the needs of patients (with) the role of the doctor"; (2) greater emphasis on general-practitioner roles in the
Thus, although surgical
care
medical-school curriculum; (3) improving standards by extension of vocational training for G.P.S and promotion of examination for the Royal College of General Practitioners. Time enough to worry about auditing " outputs " once these " inputs " are taken care of. Here in the U.S. I’m afraid that any more paperwork will sink us, and I imagine that our British colleagues are in the same boat. Finally, my experience with external audits has been that " peer review " works about as well in medicine -as it does in labour unions, the military, the clergy, and in our law associations. The name of that game is whitewash. Alhambra Medical Clinic, 1237 East Main Street, Alhambra, California 91801, U.S.A.
GEORGE T. WATTS.
ALEX GERBER.
SIR,-Mr Bond (April 12, p. 852) recommends the inclusion of a 10 ks2 resistor in E.C.G. patient leads to reduce the occurrence of diathermy burns at the sites of disposable monitoring electrodes. The protective system suggested was contained, within the 1963 edition of the Safety Code for Electro-Medical Apparatus. This recommendation was omitted from the current (1969) edition,! and does not at present appear in the draft I.E.C. regulations. For some years a number of manufacturers, including some with the highest reputations, have incorporated resistors as protective devices in their standard E.C.G. leads, and others have made this provision to special order. The method has been used as a matter of policy in a number of British hospitals, including, for instance, all the hospitals in the South Glamorgan Area Health Authority. Surgical diathermies operate over a very wide frequency range, typically at least from 400 kHz to 30 MHz.3 The current necessary to cause a burn is over 600 mA for largeplate electrodes to less than 100 mA for needle electrodes. The contact area of many disposable electrodes is at least an order of magnitude less than a typical large-plate electrode. However, the only restriction on this type of high frequency leakage current is contained in the draft LE.C. regulations. The limits imposed on 1 MHz leakage current during normal operation are 100 mA for type BF equipment (normal isolated) or 10 mA for type CF equipment (isolated equipment intended for intracardiac connections), rising to 500 mA or 50 mA, respectively, under first-fault conditions2 (para. 3.7.3). There are no regulations to apply above 1 MHz. The high frequency leakage current problem exists whether or not isolated circuitry is used. However, the problem is more severe in the case of instruments in which the protective screen of the patient cable lead is earthed, as the impedance between the inner conductor and screen, despite being very high at low frequencies, has fallen to approximately 200 Q in the region of 10 MHz, as a result of capacitive coupling. Where the screen is isolated the impedance between the conductor and earth is dependent on the capacitive coupling of the screen to earth, and of the position of surrounding earthed bodies. Thus the coupling is highly variable, but would normally be somewhat higher than 200 S2 at 10 MHz. It is clearly essential to increase these high frequency impedances to reduce the risk of burns. The effective impedances can be increased only by incorporating a protective resistor (or inductor) into the electrode connec’
INJECTION OF FREUND’S ADJUVANT SIR,-Dr Berry and others (April 12, p. 863) discussed the accidental injection of Freund’s adjuvant and its consequences. I think it is important to point out that if collagen is purified it is non-antigenic whatever its source. Even the collagen of invertebrates such as starfish, as well as ACCIDENTAL
1.
Lancet, 1972, ii,
411.
1.
Department of Health and Social Security. Hospital Technical Memorandum no. 8: Safety Code for Electro-Medical Apparatus. H.M. Stationery Office, 1963; revised 1969.
2. International Electrotechnical Commission. 62A Secretariat 10 Draft: recommendations for general safety requirements for
electrical equipment used in medical practice. 3. Dobbie, A. K. Bio-Med. Eng. 1969, 4, 206.
1087 It is unfortunate that among Mr Hole’s colleagues are do microscope their patient’s urine ". do so-and use a centrifuged specimen.
before the protective screen commences, so that the resistor attenuates the radio frequency signal to well below one-tenth of its original value. The effect of such resistors on normal 50 Hz patient leakage currents is to produce an infinitesimal improvement, that is, a reduction in leakage. The effect on the displayed E.C.G. signal is undetectable. It does, however, greatly reduce the risk of diathermy burns at E.C.G. electrode sites.
tor
Area Medical Physics Department, General Hospital, Nottingham NG1 6HA.
only a " few who Many more should
Whittier Presbyterian Intercommunity
Hospital, Whittier, California 90602, U.S.A.
CHRONIC LOW-LEVEL LEAD EXPOSURE AND MENTAL RETARDATION D. WHELPTON.
MORTALITY AND WATER SOFTNESS SIR,—The failure of Allwright et al. to find any consistent association between water hardness and deaths from heart-disease, &c., in the Los Angeles area has stimulated correspondence from Dr Meyers (Feb. 15, p. 398) and Dr Anderson and Dr Hewitt (April 12, p. 868). The effect is to leave a cloud of uncertainty over an association which many epidemiologists have hitherto regarded as fairly
strong.2 In view of the recent evidence from animal studies that lead dissolved from water pipes may play some part in increased mortality due to myocardial infarction in softwater areas such as Glasgow,3 it is desirable to point out that very little lead piping is used in the Los Angeles area; it is considered unlikely that soft water was significantly contaminated by lead in the community studied by Allwright etal.l,44 These workers’ results are in fact consistent with the hypothesis that lead dissolved from cisterns and distribution pipes is an xtiological factor in the higher mortality from heart-disease in some soft-water areas. They underline the need for caution in interpreting seemingly negative findings to which Dr Anderson and Dr Hewitt have wisely drawn attention. Department of Chemistry,
University of Reading, Whiteknights, Reading RG6 2AD.
St. Louis Children’s Hospital, 500 South Kingshighway, St. Louis, Missouri 63110, U.S.A.
SiR,—Microscopical examination, as mentioned by Dr (March 1, p. 476) and by Mr Hole (March 15, p. 632), is only a beginning of the examination of the urinary sediment. It would take only a few more seconds for the physician to centrifuge the clean-caught or catheterised urine to learn much more than from a drop of uncentrifuged urine. The physician, using a small centrifuge and a microscope, can carefully run many urines in a short time. In this type of study the physician could be much more certain in telling his patient’s urine is free of infection. (A urine culture is necessary to give the final answer as to whether or not infection exists.) The urological consultant probably sends in a urine culture because the patient had " recurrent infections ". These " recurrent infections " were probably persistent infections that had not been cured because inadequate microscopical examinations were done by the referring physicians. I suggest that all practitioners who treat people with urinary infections examine microscopically, after centrifugation, urine specimens before, during, and after treatment.
SiR,-It is clear that Dr Zarkowsky has not grasped one important points of this work-namely, that we have already established that water-lead levels, measured in the manner adopted by the present study, have a direct cor-
"
relation with the blood-lead levels and an indirect correlation with the erythrocyte delta-aminolaevulic-acid dehydratase levels of the inhabitants of the household.2 This work was also confirmed by the study of Addis and Moore.33 These studies form the basis of our reasonable assumption that raised water-lead levels relate to increased environmental exposure to lead. We have sent on copies of both papers to Dr Zarkowsky. We have also gone into detail in our paper concerning the further reasons for taking the first-flush samples of water.
The assessed fluid intake, albeit generous, was based intake of 150 ml. per kg., noting that we were considering children up to 1 year of age. A more important consideration, pointed out in the paper, is the increased absorption of lead in infancy as compared to adults both in rats4 and man.5I; Dr Zarkowsky’s statement that the " degree of mental retardation of an i.Q. less than 70 is an unusually severe
on an
Beattie, A. D., Moore, M. R., Goldberg, A., Finlayson, M. J. W. Graham, J. F., Mackie, E. M., Main, J. C., McLaren, D. A., Murdoch, R. M., Stewart, G. F. Lancet, March 15, 1975, p. 589. 2. Beattie, A. D., Moore, M. R., Miller, A. R., Devenay, W. T., Goldberg, A. Br. med. J. 1972, ii, 491. 3. Addis, G., Moore, M. R. Nature, 1974, 252, 120. 4. Kostial, K., Simonovic, I., Pisonic, M. ibid. 1971, 233, 564. 5. Clayton, B. E. Personal communication, 1974. 1.
S. P. A., Coulson, A., Detels, R., Parker, C. E. Lancet, 860. 2. W.H.O. Chron. 1973, 27, 534. 3. Moore, M. R., Goldberg, A., Carr, K., Toner, P., Lawrie, T. D. V. Scott, med. J. 1974, 19, 155. 4. Allwright, S. P. A. Personal communication.
Allwright, 1974, ii,
HAROLD ZARKOWSKY.
of the
Robin and others
"
SiR,-All studies purporting to show a relationship between undue lead exposure and brain insult suffer from being unable to document the blood-lead level, body burden of lead, or lead ingestion during the time that suspected brain damage develops. The report by Beattie et al.1 is no exception. Therefore, in this retrospective survey, how convincing are they in establishing that the retarded children had an increased exposure to lead ? The water-lead level forms the basis for the lead exposure. However, the concentration is of no value in estimating the lead exposure to these children during the first year of life, since no data are given regarding the volume of Do these raised water containing the raised lead level. levels persist in only the first 10, 20, or 100 ml. of tap water, which had resided overnight in the lead pipe ? Furthermore, the authors assume: (1) that young infants drink the gluttonous volume of 2 litres per day; and (2) that formula is prepared from the first-drawn water in the morning without previous flushing. I would have assumed that the first-drawn water was used for preparing breakfast tea. The degree of mental retardation (i.Q. less than 70) is also an unusually severe neurological complication of lead in the absence of documented encephalopathy. It would be of interest to know whether the authors found more than one child from each household with raised water-lead levels.
**We have received the following reply to Dr Zarkowsky’s letter.-ED. L.
D. BRYCE-SMITH.
URINE MICROSCOPY IN DETECTION OF BACTERIURIA
1.
JOHN A. ARCADI.
then for her to find that this is too much for her to cope with. It would be a pity if women doctors found that they could only give the time, care, and attention which their young children need in their early years at the expense of their future career. Accident and Emergency
Department, Children’s Hospital, Western Bank, Sheffield S10 2TH.
species of animal, has a collagen which is non-antigenic all species. It is only when it is contaminated with other substances such as proteins that an antigenic response will be expected. This is well known clinically, as well as experimentally, and explains the fact that certain structures, such as the aorta, can be transplanted from one species to another, whereas the femoral artery, which has a muscular wall, cannot be so transferred. The reactions reported in this case, therefore, must be due either to the adjuvant itself or to some bacteriological or other contaminant. other
to
The General Hospital, Steelhouse Lane, Birmingham B4 6NH.
CYNTHIA M. ILLINGWORTH. ELECTRICAL HAZARDS OF DISPOSABLE MONITORING ELECTRODES
MEDICAL AUDIT
SIR,-Dr Scott and Dr Davis (March 22, p. 679) ask " why is it that the United Kingdom has been slow to launch the audit procedures so common on the other side of the Atlantic?" My answer would be: " Because the U.K. has a better sense of medical priorities than the U.S." The question really revolves around what more surely, quickly, and cheaply improves the quality of medical care: measuring " outputs " by review audits or regulating inputs " of who does what to whom ? Britain is far ahead of the U.S. in this regard. For example, some one-third of the operations in this country are performed by general practitioners or other physicians not fully trained in surgery. In British hospitals, as in our own’ better-regulated institutions, all operations are performed by qualified "
surgeons.
,
in our best medical centres compares quite favourably with the best that Britain has to offer, the overall level of surgery in Britain is higher than that of the U.S. I need not spend countless hours auditing mountains of hospital charts to validate that statement, any more than I have to road test a Rolls-Royce and a Ford to determine which is the better auto, having witnessed the materials and workmanship going into each. I am more impressed with the " input " recommendations to improve the quality of general practice cited in your editorial. These were: (1) more study to reconcile "the needs of patients (with) the role of the doctor"; (2) greater emphasis on general-practitioner roles in the
Thus, although surgical
care
medical-school curriculum; (3) improving standards by extension of vocational training for G.P.S and promotion of examination for the Royal College of General Practitioners. Time enough to worry about auditing " outputs " once these " inputs " are taken care of. Here in the U.S. I’m afraid that any more paperwork will sink us, and I imagine that our British colleagues are in the same boat. Finally, my experience with external audits has been that " peer review " works about as well in medicine -as it does in labour unions, the military, the clergy, and in our law associations. The name of that game is whitewash. Alhambra Medical Clinic, 1237 East Main Street, Alhambra, California 91801, U.S.A.
GEORGE T. WATTS.
ALEX GERBER.
SIR,-Mr Bond (April 12, p. 852) recommends the inclusion of a 10 ks2 resistor in E.C.G. patient leads to reduce the occurrence of diathermy burns at the sites of disposable monitoring electrodes. The protective system suggested was contained, within the 1963 edition of the Safety Code for Electro-Medical Apparatus. This recommendation was omitted from the current (1969) edition,! and does not at present appear in the draft I.E.C. regulations. For some years a number of manufacturers, including some with the highest reputations, have incorporated resistors as protective devices in their standard E.C.G. leads, and others have made this provision to special order. The method has been used as a matter of policy in a number of British hospitals, including, for instance, all the hospitals in the South Glamorgan Area Health Authority. Surgical diathermies operate over a very wide frequency range, typically at least from 400 kHz to 30 MHz.3 The current necessary to cause a burn is over 600 mA for largeplate electrodes to less than 100 mA for needle electrodes. The contact area of many disposable electrodes is at least an order of magnitude less than a typical large-plate electrode. However, the only restriction on this type of high frequency leakage current is contained in the draft LE.C. regulations. The limits imposed on 1 MHz leakage current during normal operation are 100 mA for type BF equipment (normal isolated) or 10 mA for type CF equipment (isolated equipment intended for intracardiac connections), rising to 500 mA or 50 mA, respectively, under first-fault conditions2 (para. 3.7.3). There are no regulations to apply above 1 MHz. The high frequency leakage current problem exists whether or not isolated circuitry is used. However, the problem is more severe in the case of instruments in which the protective screen of the patient cable lead is earthed, as the impedance between the inner conductor and screen, despite being very high at low frequencies, has fallen to approximately 200 Q in the region of 10 MHz, as a result of capacitive coupling. Where the screen is isolated the impedance between the conductor and earth is dependent on the capacitive coupling of the screen to earth, and of the position of surrounding earthed bodies. Thus the coupling is highly variable, but would normally be somewhat higher than 200 S2 at 10 MHz. It is clearly essential to increase these high frequency impedances to reduce the risk of burns. The effective impedances can be increased only by incorporating a protective resistor (or inductor) into the electrode connec’
INJECTION OF FREUND’S ADJUVANT SIR,-Dr Berry and others (April 12, p. 863) discussed the accidental injection of Freund’s adjuvant and its consequences. I think it is important to point out that if collagen is purified it is non-antigenic whatever its source. Even the collagen of invertebrates such as starfish, as well as ACCIDENTAL
1.
Lancet, 1972, ii,
411.
1.
Department of Health and Social Security. Hospital Technical Memorandum no. 8: Safety Code for Electro-Medical Apparatus. H.M. Stationery Office, 1963; revised 1969.
2. International Electrotechnical Commission. 62A Secretariat 10 Draft: recommendations for general safety requirements for
electrical equipment used in medical practice. 3. Dobbie, A. K. Bio-Med. Eng. 1969, 4, 206.
1087 It is unfortunate that among Mr Hole’s colleagues are do microscope their patient’s urine ". do so-and use a centrifuged specimen.
before the protective screen commences, so that the resistor attenuates the radio frequency signal to well below one-tenth of its original value. The effect of such resistors on normal 50 Hz patient leakage currents is to produce an infinitesimal improvement, that is, a reduction in leakage. The effect on the displayed E.C.G. signal is undetectable. It does, however, greatly reduce the risk of diathermy burns at E.C.G. electrode sites.
tor
Area Medical Physics Department, General Hospital, Nottingham NG1 6HA.
only a " few who Many more should
Whittier Presbyterian Intercommunity
Hospital, Whittier, California 90602, U.S.A.
CHRONIC LOW-LEVEL LEAD EXPOSURE AND MENTAL RETARDATION D. WHELPTON.
MORTALITY AND WATER SOFTNESS SIR,—The failure of Allwright et al. to find any consistent association between water hardness and deaths from heart-disease, &c., in the Los Angeles area has stimulated correspondence from Dr Meyers (Feb. 15, p. 398) and Dr Anderson and Dr Hewitt (April 12, p. 868). The effect is to leave a cloud of uncertainty over an association which many epidemiologists have hitherto regarded as fairly
strong.2 In view of the recent evidence from animal studies that lead dissolved from water pipes may play some part in increased mortality due to myocardial infarction in softwater areas such as Glasgow,3 it is desirable to point out that very little lead piping is used in the Los Angeles area; it is considered unlikely that soft water was significantly contaminated by lead in the community studied by Allwright etal.l,44 These workers’ results are in fact consistent with the hypothesis that lead dissolved from cisterns and distribution pipes is an xtiological factor in the higher mortality from heart-disease in some soft-water areas. They underline the need for caution in interpreting seemingly negative findings to which Dr Anderson and Dr Hewitt have wisely drawn attention. Department of Chemistry,
University of Reading, Whiteknights, Reading RG6 2AD.
St. Louis Children’s Hospital, 500 South Kingshighway, St. Louis, Missouri 63110, U.S.A.
SiR,—Microscopical examination, as mentioned by Dr (March 1, p. 476) and by Mr Hole (March 15, p. 632), is only a beginning of the examination of the urinary sediment. It would take only a few more seconds for the physician to centrifuge the clean-caught or catheterised urine to learn much more than from a drop of uncentrifuged urine. The physician, using a small centrifuge and a microscope, can carefully run many urines in a short time. In this type of study the physician could be much more certain in telling his patient’s urine is free of infection. (A urine culture is necessary to give the final answer as to whether or not infection exists.) The urological consultant probably sends in a urine culture because the patient had " recurrent infections ". These " recurrent infections " were probably persistent infections that had not been cured because inadequate microscopical examinations were done by the referring physicians. I suggest that all practitioners who treat people with urinary infections examine microscopically, after centrifugation, urine specimens before, during, and after treatment.
SiR,-It is clear that Dr Zarkowsky has not grasped one important points of this work-namely, that we have already established that water-lead levels, measured in the manner adopted by the present study, have a direct cor-
"
relation with the blood-lead levels and an indirect correlation with the erythrocyte delta-aminolaevulic-acid dehydratase levels of the inhabitants of the household.2 This work was also confirmed by the study of Addis and Moore.33 These studies form the basis of our reasonable assumption that raised water-lead levels relate to increased environmental exposure to lead. We have sent on copies of both papers to Dr Zarkowsky. We have also gone into detail in our paper concerning the further reasons for taking the first-flush samples of water.
The assessed fluid intake, albeit generous, was based intake of 150 ml. per kg., noting that we were considering children up to 1 year of age. A more important consideration, pointed out in the paper, is the increased absorption of lead in infancy as compared to adults both in rats4 and man.5I; Dr Zarkowsky’s statement that the " degree of mental retardation of an i.Q. less than 70 is an unusually severe
on an
Beattie, A. D., Moore, M. R., Goldberg, A., Finlayson, M. J. W. Graham, J. F., Mackie, E. M., Main, J. C., McLaren, D. A., Murdoch, R. M., Stewart, G. F. Lancet, March 15, 1975, p. 589. 2. Beattie, A. D., Moore, M. R., Miller, A. R., Devenay, W. T., Goldberg, A. Br. med. J. 1972, ii, 491. 3. Addis, G., Moore, M. R. Nature, 1974, 252, 120. 4. Kostial, K., Simonovic, I., Pisonic, M. ibid. 1971, 233, 564. 5. Clayton, B. E. Personal communication, 1974. 1.
S. P. A., Coulson, A., Detels, R., Parker, C. E. Lancet, 860. 2. W.H.O. Chron. 1973, 27, 534. 3. Moore, M. R., Goldberg, A., Carr, K., Toner, P., Lawrie, T. D. V. Scott, med. J. 1974, 19, 155. 4. Allwright, S. P. A. Personal communication.
Allwright, 1974, ii,
HAROLD ZARKOWSKY.
of the
Robin and others
"
SiR,-All studies purporting to show a relationship between undue lead exposure and brain insult suffer from being unable to document the blood-lead level, body burden of lead, or lead ingestion during the time that suspected brain damage develops. The report by Beattie et al.1 is no exception. Therefore, in this retrospective survey, how convincing are they in establishing that the retarded children had an increased exposure to lead ? The water-lead level forms the basis for the lead exposure. However, the concentration is of no value in estimating the lead exposure to these children during the first year of life, since no data are given regarding the volume of Do these raised water containing the raised lead level. levels persist in only the first 10, 20, or 100 ml. of tap water, which had resided overnight in the lead pipe ? Furthermore, the authors assume: (1) that young infants drink the gluttonous volume of 2 litres per day; and (2) that formula is prepared from the first-drawn water in the morning without previous flushing. I would have assumed that the first-drawn water was used for preparing breakfast tea. The degree of mental retardation (i.Q. less than 70) is also an unusually severe neurological complication of lead in the absence of documented encephalopathy. It would be of interest to know whether the authors found more than one child from each household with raised water-lead levels.
**We have received the following reply to Dr Zarkowsky’s letter.-ED. L.
D. BRYCE-SMITH.
URINE MICROSCOPY IN DETECTION OF BACTERIURIA
1.
JOHN A. ARCADI.
