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.
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.
