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CONGENITAL DIAPHRAGMATIC HERNIA
975 To relate the plasma-bicarbonate concentration to the total excess or deficit of hydrogen ions in the whole body an empirical correction factor may be used.2 On the other hand, the concept of whole blood " buffer base " sets out to give a comprehensive description of the whole blood buffer reaction. The term " buffer base ", as defined by Singer and Hastings,3 is unacceptable because it is not framed in accordance with proper chemical nomenclature; but if the modification of Astrup and his colleagues 4 is used, changes in the whole blood buffer status may be presented correctly with the phrase " base excess or deficit". The difficulty lies here: it is well known that the buffers of blood contribute but a very small fraction of the total body buffering capacity. If the buffer capacity per kg.
of total body-weight is identical with that of a kilogramme of blood, the acid-base status of the whole body can be directly measured from the acid-base status of the blood. But if the buffer capacity of the whole body differs from that of blood (weight for weight), measurement of the blood " base excess or deficit " may reflect, but cannot accurately describe, changes in the acid-base status of the whole body. There is no inherent reason why the buffer capacity of the whole body should be identical with that of isolated blood. Such evidence as there is suggests that the two are not entirely dissimilar; but the relationship has not yet been satisfactorily elucidated, and in 5 any case, is likely to be ephemeral. Therefore it must be recognised that the blood " base excess or deficit " is no more absolute in its description of changes in the whole body acid-base status than the value of the " standard " bicarbonate. In practice these two modes of measurement give exactly parallel results. This being so, why not adhere to the simpler proposition of using the plasma-bicarbonate concentration as the index of the whole body acid-base status, rather than the base excess or deficit " more complex notion of blood with its illusion of perfection ? The advantages of using the bicarbonate buffer alone as the index are: "
(a) It is the most ubiquitous and immediately effective of the buffers in the body. (b) The concentration of its component carbonic acid is hence it provides a more suitable framework in which to express acid-base disturbances which may be of either respiratory or non-respiratory origin. (c) It is directly measurable as the total plasma-CO2 minus the dissolved CO2, (d) The numerical figure for its concentration can be presented in a simple form as the " standard " bicarbonate, without involving the concentrations of hxmoglobin and other blood buffer agents. (e) The values of pH, carbon-dioxide tension, and bicarbonate concentration can be readily presented in graphic form. If the value of two of these parameters is plotted on an acid-base diagram the third may be derived immediately, their interrelationships easily understood, and, with sequential analyses, the course of a disturbance followed over a period of time.
directly dependent
on
respiration;
L. J. Henderson, who in 1908 first developed the concept of buffering in biological fluids, was of the opinion that the diversity and adaptability of physiological processes precludes absolute precision of definition in this subject 6; that opinion remains valid today. Wessex Regional Respiratory
Poliomyelitis Unit, Hospital,
Priorsdean
Portsmouth.
M. W. GLOSSOP.
2. Palmer, W. W., Van Slyke, D. D. J. biol. Chem. 1917, 32, 499. 3. Singer, R. B., Hastings, A. B. Medicine, 1948, 27, 223. 4. Astrup, P., Jørgensen, K., Andersen, O. S., Engel, K. Lancet, 1960, 5. 6.
i, 1035. Glossop, M. W. Brit. J. Anœsth. 1962, 34, 66. Henderson, L. J. Amer. J. Physiol. 1908, 21, 427.
VISUAL DEFECTS IN CHILDREN
SIR,-Your annotation of April 7 draws attention to the need for early and regular examination of children’s eyes in order that refractive errors can be corrected, squints detected and treated, and incipient disease detected before harm, often irreparable, has been done. You say this is essentially a medical responsibility and point out the inadequate numbers of ophthalmologists available to carry out this work in the school eye service. Granted that the overall responsibility for the health of the community rests with the medical profession, it would nevertheless seem logical that they should draw upon the services of allied professions in the interests of the patient. The examination and care of the eyesight of children is a case in point. The services of trained qualified Stateregistered ophthalmic opticians are already being used to a limited extent in the Hospital Eye Service and in the care of children’s eyes through the normal machinery of the Supplementary Ophthalmic Service. In view of the shortage of consultant ophthalmologists we consider that with proper safeguards much more use could and should be made of the ophthalmic opticians in this vital part of the health services of the nation. Association of Optical Practitioners, London, W.1.
C. S. FLICK.
CONGENITAL DIAPHRAGMATIC HERNIA
SIR,-Dr. Butler and Dr. Claireaux (March 31) refer to a woman who lost two infants from this malformation. A woman in this town lost two children from the same cause soon after delivery, one in 1951, the other in 1960. The findings in each case were similar: a left posterolateral defect, with most of the intestines in the chest on each occasion; and, in the first child, kidney, adrenal, and spleen in addition. Both children were male. They were the third and seventh children in the family, the other five all being healthy females. The General Hospital, R. G. WELCH West Hartlepool, R. T. COOKE. Co. Durham. THE LOGIC OF HOSPITAL CASE-NOTES
SIR,-Mr. Brooke’sinteresting suggestions doubtless adequately safeguard the interests of the patient on his readmission to hospital later. But his opinion that caserecords are of little value in research is, I think, unjustified. If records are confined to one central records office so that specialist departments can destroy copies after a limited period, properly cross-indexed and microphotographed before destruction of the original, then none of the disadvantages which Mr. Brooke mentioned accrue. The retrospective survey may be as valuable as the prospective one in accurately assessing something and it also has some advantages over the prospective one. Most important, a quick answer can be obtained because the information is already there and subsidiary benefits are the better planning of a prospective trial and shortening it by the addition of firm and valid evidence from the retrospective survey. I trust I am not being gratuitously unkind by giving the gentle reminder that silly questions get silly answers. Obviously it is of no use looking for Pumpernickel’s sign before Pumpernickel described it or before its association with knock-knee was known. A brief illustration may suffice. A patient with severe carbon-monoxide poisoning at the Grace-New Haven Hospital, seen with Prof. J. W. Meigs, had a severe " burn " which could not have been thermal or chemical in origin. As all
of total body-weight is identical with that of a kilogramme of blood, the acid-base status of the whole body can be directly measured from the acid-base status of the blood. But if the buffer capacity of the whole body differs from that of blood (weight for weight), measurement of the blood " base excess or deficit " may reflect, but cannot accurately describe, changes in the acid-base status of the whole body. There is no inherent reason why the buffer capacity of the whole body should be identical with that of isolated blood. Such evidence as there is suggests that the two are not entirely dissimilar; but the relationship has not yet been satisfactorily elucidated, and in 5 any case, is likely to be ephemeral. Therefore it must be recognised that the blood " base excess or deficit " is no more absolute in its description of changes in the whole body acid-base status than the value of the " standard " bicarbonate. In practice these two modes of measurement give exactly parallel results. This being so, why not adhere to the simpler proposition of using the plasma-bicarbonate concentration as the index of the whole body acid-base status, rather than the base excess or deficit " more complex notion of blood with its illusion of perfection ? The advantages of using the bicarbonate buffer alone as the index are: "
(a) It is the most ubiquitous and immediately effective of the buffers in the body. (b) The concentration of its component carbonic acid is hence it provides a more suitable framework in which to express acid-base disturbances which may be of either respiratory or non-respiratory origin. (c) It is directly measurable as the total plasma-CO2 minus the dissolved CO2, (d) The numerical figure for its concentration can be presented in a simple form as the " standard " bicarbonate, without involving the concentrations of hxmoglobin and other blood buffer agents. (e) The values of pH, carbon-dioxide tension, and bicarbonate concentration can be readily presented in graphic form. If the value of two of these parameters is plotted on an acid-base diagram the third may be derived immediately, their interrelationships easily understood, and, with sequential analyses, the course of a disturbance followed over a period of time.
directly dependent
on
respiration;
L. J. Henderson, who in 1908 first developed the concept of buffering in biological fluids, was of the opinion that the diversity and adaptability of physiological processes precludes absolute precision of definition in this subject 6; that opinion remains valid today. Wessex Regional Respiratory
Poliomyelitis Unit, Hospital,
Priorsdean
Portsmouth.
M. W. GLOSSOP.
2. Palmer, W. W., Van Slyke, D. D. J. biol. Chem. 1917, 32, 499. 3. Singer, R. B., Hastings, A. B. Medicine, 1948, 27, 223. 4. Astrup, P., Jørgensen, K., Andersen, O. S., Engel, K. Lancet, 1960, 5. 6.
i, 1035. Glossop, M. W. Brit. J. Anœsth. 1962, 34, 66. Henderson, L. J. Amer. J. Physiol. 1908, 21, 427.
VISUAL DEFECTS IN CHILDREN
SIR,-Your annotation of April 7 draws attention to the need for early and regular examination of children’s eyes in order that refractive errors can be corrected, squints detected and treated, and incipient disease detected before harm, often irreparable, has been done. You say this is essentially a medical responsibility and point out the inadequate numbers of ophthalmologists available to carry out this work in the school eye service. Granted that the overall responsibility for the health of the community rests with the medical profession, it would nevertheless seem logical that they should draw upon the services of allied professions in the interests of the patient. The examination and care of the eyesight of children is a case in point. The services of trained qualified Stateregistered ophthalmic opticians are already being used to a limited extent in the Hospital Eye Service and in the care of children’s eyes through the normal machinery of the Supplementary Ophthalmic Service. In view of the shortage of consultant ophthalmologists we consider that with proper safeguards much more use could and should be made of the ophthalmic opticians in this vital part of the health services of the nation. Association of Optical Practitioners, London, W.1.
C. S. FLICK.
CONGENITAL DIAPHRAGMATIC HERNIA
SIR,-Dr. Butler and Dr. Claireaux (March 31) refer to a woman who lost two infants from this malformation. A woman in this town lost two children from the same cause soon after delivery, one in 1951, the other in 1960. The findings in each case were similar: a left posterolateral defect, with most of the intestines in the chest on each occasion; and, in the first child, kidney, adrenal, and spleen in addition. Both children were male. They were the third and seventh children in the family, the other five all being healthy females. The General Hospital, R. G. WELCH West Hartlepool, R. T. COOKE. Co. Durham. THE LOGIC OF HOSPITAL CASE-NOTES
SIR,-Mr. Brooke’sinteresting suggestions doubtless adequately safeguard the interests of the patient on his readmission to hospital later. But his opinion that caserecords are of little value in research is, I think, unjustified. If records are confined to one central records office so that specialist departments can destroy copies after a limited period, properly cross-indexed and microphotographed before destruction of the original, then none of the disadvantages which Mr. Brooke mentioned accrue. The retrospective survey may be as valuable as the prospective one in accurately assessing something and it also has some advantages over the prospective one. Most important, a quick answer can be obtained because the information is already there and subsidiary benefits are the better planning of a prospective trial and shortening it by the addition of firm and valid evidence from the retrospective survey. I trust I am not being gratuitously unkind by giving the gentle reminder that silly questions get silly answers. Obviously it is of no use looking for Pumpernickel’s sign before Pumpernickel described it or before its association with knock-knee was known. A brief illustration may suffice. A patient with severe carbon-monoxide poisoning at the Grace-New Haven Hospital, seen with Prof. J. W. Meigs, had a severe " burn " which could not have been thermal or chemical in origin. As all