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ANÆSTHESIA IN CARDIAC DISEASE
624 have confirmed the close correlation between the bloodadrenaline level and the return of consciousness. These results have strengthened the hypothesis previously put forward6 that the effect of administering glutamic acid and related drugs is due to an unspecific mechanism of a pharmacological (more exactly a sympathomimetic) nature. There is as yet no convincing evidence for a connection between the pharmacological effects of glutamic acid and its functions in intermediary
COMPARISON OF DEATIIS FROM "EPIDEMIC" AND POLIOMYELITIS BY AGE-GROUPS
"ENDEMIC""
metabolismResearch Department, Run-well Hospital, near Wickford, Essex.
H. WEIL-MALHERBE.
ANÆSTHESIA IN CARDIAC DISEASE SiR,-In last week’s editorial on this subject you did not mention a simple measure that adds to the safety of anaesthesia in patients with cardiac disease and others who are seriously ill. You rightly stated that the most dangerous moments are during induction. Danger is greatly increased should anoxic anoxia occur, as it is apt to, at this stage. This can be guarded against by administering oxygen from the anaesthetic apparatus for a few minutes before the ansesthetic is started and by continuing this administration during induction. For this purpose oxygen is allowed to flow freely through the by-pass, and the expiratory valve is left open so that re-breathing does not occur. In this way much of the nitrogen in the lungs is replaced by oxygen, which forms a reserve sufficient for several minutes. I am not original in suggesting this measure, but fear that it is too seldom practised and that as a result lives may occasionally be lost. You went on to advise against the use of thiopentone in cases of adhesive pericarditis. It would be interesting to know which alternative agent you consider most suitable for induction in these patients. St. Thomas’s Hospital, J. G. BOURNE. London, S.E.1.
* * * We are indebted to Dr. Bourne for drawing attention to this simple measure, which is, as he states, too seldom practised. Parry Brown and Sellick7 induce patients suffering from adhesive pericarditis with nitrous oxide, oxygen, and ether, after a preliminary cricothyroid injection of 10% cocaine. The disadvantage of this technique is the difficulty of achieving induction with satisfactory oxygenation, and many anaesthetists therefore prefer cyclopropane and oxygen. Here oxygenation is at all times complete and the danger from arrhythmias seems to be theoretical rather than practical, as Dr. Bourne himself has shown.8-ED. L.
as the same disease. My hypothesis does not demand that endemic poliomyelitis shall have disappeared; it is presumably still at work and we know that it has always attacked just those two age-groups which show the highest incidence in his figures. If, therefore, we are to get a true picture of epidemic,
opposed to endemic, poliomyelitis deaths, we must subtract from the total for 1947-51 those which we would have expected to have resulted from endemic poliomyelitis alone. The result is interesting. Thus, I have obtained the " expected " endemic poliomyelitis deaths by multiplying the figures for 1939, which he takes as a typical endemic year, by five to represent a five-year period, and I have subtracted them from the total figures he gives for 1947-51, with the results shown in the accompanying table. It will be seen that the apparent age differentiation for epidemic poliomyelitis was almost entirely explained by the inclusion of the endemic figures, particularly in the 5-10 quinquennium. It is true that the 0-5 age-group still has the highest incidence of all groups, but there are a number of possible explanations,-notably the fact that this group is more exposed to one of the known precipitating factors-namely, immunisation procedures-than This 0-5 age-group is to me particularly any other. interesting, for it contains a group virtually unrepresented in the endemic figures-i.e., the infants of 6 months and under, in whom the disease was practically unknown in this country before the appearance of epidemic poliomyelitis. Since poliomyelitis immunity, like measles immunity, appears to be acquired from the mother and declines gradually during the first months of life, the sudden susceptibility of the infants in this age-group is to me further proof of the new susceptibility of an older age-group-their mother’s-and further evidence in favour of an immunogenically new " rather exalted old " virus. than an I am grateful to Dr. Breen (Aug. 22) for so neatly exposing the weakness of Dr. Ritchie Russell’s argument (Aug. 15). Let me quickly say that I do not think transmission by personal contact is by any means the only consideration in poliomyelitis epidemics. Climate and other factors undoubtedly have a very definite effect on the incidence of the disease. Most of them are, however, both unpredictable and uncontrollable, and I therefore prefer to concentrate on the transmission of the virus, which after all is, apart from its human victim, the only sine qua non of the disease. Closure of schools and the outdoor life of the population in the summer may well work against the virus in a season which appears otherwise to favour it-witness the outbreaks of poliomyelitis in camps which replace schools at this time of year. I shall deal with only one point in Dr. Ritchie Russell’s letter. He says "... let us ensure that the fashionable insistence on isolation does not result in cases of poliomyelitis being isolated also from important medical facilities." There has of late been a too-ready acceptance of the astonishing assumption that if a patient with poliomyelitis dies in an isolation hospital he dies for lack of medical care, and if he dies in a general hospital, or more as
"
"
PREVENTION OF POLIOMYELITIS SiR.,-I should like to answer one or two of the
points
raised by your correspondents on the subject of my article of Aug. 8. First, I must apologise to Dr. Hamilton (Aug. 22) for appearing to underestimate the problem of tuberculosis, of whose size I am well aware. The phrase should have read " common acute communicable disease " and I hope he will accept this amendment. Dr. Paul’s analysis (Aug. 22) of deaths from poliomyelitis in quinquennial age-groups is very interesting, but I should like to challenge him on one point. He demonstrates that the first two quinquennia of life still show the highest number of deaths, and argues that this is evidence that we are more likely to be dealing with an " exalted " familiar virus than with a "new" virus, since " if the epidemic virus were a new one attacking a virgin community one would expect little or no age differentiation." But he ignores an important fact-that epidemic and endemic poliomyelitis are being notified 6. 7. 8.
Weil-Malherbe, H. Physiol. Rev. 1950, 30, 549 ; Biochemical Society Symposia, 1952, 8, 16. Parry Brown, A. I., Sellick, B.A. Anœsthesia, 1953, 8, 4. Bourne, J. G. Lancet, 1952, ii, 705.
COMPARISON OF DEATIIS FROM "EPIDEMIC" AND POLIOMYELITIS BY AGE-GROUPS
"ENDEMIC""
metabolismResearch Department, Run-well Hospital, near Wickford, Essex.
H. WEIL-MALHERBE.
ANÆSTHESIA IN CARDIAC DISEASE SiR,-In last week’s editorial on this subject you did not mention a simple measure that adds to the safety of anaesthesia in patients with cardiac disease and others who are seriously ill. You rightly stated that the most dangerous moments are during induction. Danger is greatly increased should anoxic anoxia occur, as it is apt to, at this stage. This can be guarded against by administering oxygen from the anaesthetic apparatus for a few minutes before the ansesthetic is started and by continuing this administration during induction. For this purpose oxygen is allowed to flow freely through the by-pass, and the expiratory valve is left open so that re-breathing does not occur. In this way much of the nitrogen in the lungs is replaced by oxygen, which forms a reserve sufficient for several minutes. I am not original in suggesting this measure, but fear that it is too seldom practised and that as a result lives may occasionally be lost. You went on to advise against the use of thiopentone in cases of adhesive pericarditis. It would be interesting to know which alternative agent you consider most suitable for induction in these patients. St. Thomas’s Hospital, J. G. BOURNE. London, S.E.1.
* * * We are indebted to Dr. Bourne for drawing attention to this simple measure, which is, as he states, too seldom practised. Parry Brown and Sellick7 induce patients suffering from adhesive pericarditis with nitrous oxide, oxygen, and ether, after a preliminary cricothyroid injection of 10% cocaine. The disadvantage of this technique is the difficulty of achieving induction with satisfactory oxygenation, and many anaesthetists therefore prefer cyclopropane and oxygen. Here oxygenation is at all times complete and the danger from arrhythmias seems to be theoretical rather than practical, as Dr. Bourne himself has shown.8-ED. L.
as the same disease. My hypothesis does not demand that endemic poliomyelitis shall have disappeared; it is presumably still at work and we know that it has always attacked just those two age-groups which show the highest incidence in his figures. If, therefore, we are to get a true picture of epidemic,
opposed to endemic, poliomyelitis deaths, we must subtract from the total for 1947-51 those which we would have expected to have resulted from endemic poliomyelitis alone. The result is interesting. Thus, I have obtained the " expected " endemic poliomyelitis deaths by multiplying the figures for 1939, which he takes as a typical endemic year, by five to represent a five-year period, and I have subtracted them from the total figures he gives for 1947-51, with the results shown in the accompanying table. It will be seen that the apparent age differentiation for epidemic poliomyelitis was almost entirely explained by the inclusion of the endemic figures, particularly in the 5-10 quinquennium. It is true that the 0-5 age-group still has the highest incidence of all groups, but there are a number of possible explanations,-notably the fact that this group is more exposed to one of the known precipitating factors-namely, immunisation procedures-than This 0-5 age-group is to me particularly any other. interesting, for it contains a group virtually unrepresented in the endemic figures-i.e., the infants of 6 months and under, in whom the disease was practically unknown in this country before the appearance of epidemic poliomyelitis. Since poliomyelitis immunity, like measles immunity, appears to be acquired from the mother and declines gradually during the first months of life, the sudden susceptibility of the infants in this age-group is to me further proof of the new susceptibility of an older age-group-their mother’s-and further evidence in favour of an immunogenically new " rather exalted old " virus. than an I am grateful to Dr. Breen (Aug. 22) for so neatly exposing the weakness of Dr. Ritchie Russell’s argument (Aug. 15). Let me quickly say that I do not think transmission by personal contact is by any means the only consideration in poliomyelitis epidemics. Climate and other factors undoubtedly have a very definite effect on the incidence of the disease. Most of them are, however, both unpredictable and uncontrollable, and I therefore prefer to concentrate on the transmission of the virus, which after all is, apart from its human victim, the only sine qua non of the disease. Closure of schools and the outdoor life of the population in the summer may well work against the virus in a season which appears otherwise to favour it-witness the outbreaks of poliomyelitis in camps which replace schools at this time of year. I shall deal with only one point in Dr. Ritchie Russell’s letter. He says "... let us ensure that the fashionable insistence on isolation does not result in cases of poliomyelitis being isolated also from important medical facilities." There has of late been a too-ready acceptance of the astonishing assumption that if a patient with poliomyelitis dies in an isolation hospital he dies for lack of medical care, and if he dies in a general hospital, or more as
"
"
PREVENTION OF POLIOMYELITIS SiR.,-I should like to answer one or two of the
points
raised by your correspondents on the subject of my article of Aug. 8. First, I must apologise to Dr. Hamilton (Aug. 22) for appearing to underestimate the problem of tuberculosis, of whose size I am well aware. The phrase should have read " common acute communicable disease " and I hope he will accept this amendment. Dr. Paul’s analysis (Aug. 22) of deaths from poliomyelitis in quinquennial age-groups is very interesting, but I should like to challenge him on one point. He demonstrates that the first two quinquennia of life still show the highest number of deaths, and argues that this is evidence that we are more likely to be dealing with an " exalted " familiar virus than with a "new" virus, since " if the epidemic virus were a new one attacking a virgin community one would expect little or no age differentiation." But he ignores an important fact-that epidemic and endemic poliomyelitis are being notified 6. 7. 8.
Weil-Malherbe, H. Physiol. Rev. 1950, 30, 549 ; Biochemical Society Symposia, 1952, 8, 16. Parry Brown, A. I., Sellick, B.A. Anœsthesia, 1953, 8, 4. Bourne, J. G. Lancet, 1952, ii, 705.