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A CALCIUM-INFUSION TEST
1014
produced
remarkable short-term
to that from drastic
improvement surgical procedures.
at least
In July, 1938, the late Mr. James Joyce, the Reading Pathological Society, said :
equal
addressing
" It is my firm opinion that until cancer can be treated from a new angle such as endocrinology may provide, we cannot hope to obtain the results which will satisfy us in any field of cancer therapy."
years later it would appear that we can but re-echo his words, and hope that this branch of endocrinology will be raised to the status its importance merits. W. G. TAIT. Reading.
Eighteen
INTERMITTENT POSITIVE-PRESSURE RESPIRATION case of respiratory paralysis Dr. Lawes and Dr. Harries (May 26) will be carefully studied by all who might have charge of such The methods used are known to have been a case. inadequate and so the problem becomes twofold: (1) What treatment was more likely to have succeeded ? (2) Is all the necessary equipment at hand to treat a similar case should it be admitted to our own respiratory unit’? We would like to comment on some details of the treatment used and to put forward alternative suggestions. The tracheotomy tube was probably of too small a diameter, and the shape was a major cause of death.
SiR,-The very interesting
described
by
We feel that the tube designed on this unitwould have given better results. The metal linings are now made by Thackray, and Magill’s tubes in good condition are readily available ; so there is no question of special rubber tubes having perished before being wanted. We have not seen any tracheal ulceration develop whilst using these tubes, and have had the added pleasure of seeing an established ulcer heal in a few days when the first of our tubes was put into service.
The following tests probably explain why the infant had increasing carbon-dioxide tension even though the correct ventilation was apparently taking place as shown by measuring the air leaving the expiratory port of the Stott valve. A Stott valve was connected to a Radcliffe machine which had a gas-meter recording the air intake. The patient was represented by a spirometer with variable weights on the bell. Expired air was measured by another spirometer ; unidirectional valves and a pressure gauge were also used at times. Results were variable not only when using different valves but also when repeating the same test on the same valve ; but the over-all picture was consistent. Our conclusions were that air can pass from the inlet to the outlet without going to the patient. The volume leaving the Stott valve will equal that entering the machine but will be quite different from that which reaches the patient. The following are two average examples : of 600 ml. entering the machine and eventually leaving the valve, only 400 ml. reached the " patient." Similarly of 450 ml. only 300 reached the " patient." The " lost " air is thought to be compressed in the tubing during inspiration and released during expiration. In clinical use we repeatedly found that the apparent tidal volume had to be maintained in the region of 50% above the figure given on the Radford nomogram, and any reduction in this volume was quickly followed by protests from the patient. When a B.O.C. flutter-valve was submitted to the same test this discrepancy did not occur. We have found that the B.O.C. valve, being made of softer rubber, produces a 2-5 cm. water-pressure between the machine and the valve and less than 0-5 cm. water-pressure in the airway, whilst the Stott valve produces 6-8 cm. pressure between the machine and the valve and a sustained pressure of 1-5-2 cm. water-pressure in the airway. This may interfere with the gaseous exchange in the lungs. It was found, however, almost at the cost of a life, that the diaphragm of the B.O.C. valve can be inserted reversed and this should be appreciated by all who use them. Because the percentage of dead space rises as the tidal volume falls a slower rate of ventilation with increased tidal volume should have helped to reduce the carbon-dioxide 1. Hodges, R. J. H., Morley, R., O’Driscoll, W. Lancet, Jan. 7, 1956, p. 26.
B., McDonald, I.
tension in the infant. Had this not resulted, the temporary use of an efficient absorber could have been tried. Whilst a circle absorber is likely to have been effective, Sandiford’s2 to-and-fro one is almost without dead space and so should be better. With a circle absorber in use, minute volumes can be read on a gas-meter. We are in full agreement that the inflationary pattern of the Radcliffe is too prolonged. By redesigning the escapement mechanism we can now vary the wave pattern at will.
To summarise, we suggest that the infant was receiving deficient volume of air through too narrow a tube ; and from the many tests which we have done on the Stott valve during recent months we consider the performance to be very variable and that it is not reasonably possible to measure the tidal volume being delivered. One is left to control the patient largely on clinical observations. There is still room for considerable improvement in our knowledge of techniques and machinery. Is all a
possible being done to pool existing experience and knowledge which is being gained on a few isolated units which are treating in all comparatively few patients each year ?’? Portsmouth Poliomyelitis Unit.
H. B. C. SANDIFORD I. MCDONALD.
A CALCIUM-INFUSION TEST
SiR,-Dr. Nordin and Dr. Fraser, in your issue of June 2, record an experiment in which 98 patients, including " 21 patients in whom there was no reason to suspect metabolic bone disease " and " 30 patients with miscellaneous conditions in which bone disease might be suspected " were subjected to a four-hour intravenous infusion. Would it not be a good principle to state clearly in all accounts of experiments utilising human controls that the human controls are volunteers and to record the means by which their cooperation was achieved’? ANTHONY RYLE. London, N.BY.5.
***Dr. Ryle’s letter has been shown to Dr. Russell reply follows.-ED. L. SiR,ňBoth the preliminary and other subsequent tests of the intravenous procedure described were performed on volunteers amongst the research team. With all patients, agreement to the performance of the test procedure was of course obtained. Those not initially suspected of bone disease willingly gave their consent. We had every reason to believe, from personal experience, that the test was devoid of any risk, and in fact no untoward symptoms Fraser whose
or
effects followed the test in any instance.
Postgraduate Medical School, London, W.12.
RUSSELL FRASER.
ANTENATAL CARE
A concerted effort against toxaemia of pregSiR,-" " need not involve the chairmen of boards of nancy and of governors, hospital management committees," as implied by the Ministry memorandum to which you referred last week. It must involve the careful study of the prevention of Eclampsia and Pre-Eclampsia3 wherein R. H. J. Hamlin sets out the " seven steps " by means of which he eradicated eclampsia at the Women’s Hospital, Crown Street, Sydney, together with acceptance of his two points : (a) early detection by weight increase between 20th and 30th weeks; and (b) institution of a high-protein, high-vitamin, and low-carbohydrate diet at that stage. The Ministry’s memorandum pays lip service to Hamlin in Australia the practice of the Women’s Hospital, Crown Street, Sydney, described by Hamlin "), but further on states : " a routine designed to detect the smallest deviation from the normal, for example, a rising blood pressure ... slight oedema or unduly rapid weight "
2. 3.
Sandiford, H. B. C. Lancet, 1952, i, 64.
Anœsthesia, 1953, 8, 122.
produced
remarkable short-term
to that from drastic
improvement surgical procedures.
at least
In July, 1938, the late Mr. James Joyce, the Reading Pathological Society, said :
equal
addressing
" It is my firm opinion that until cancer can be treated from a new angle such as endocrinology may provide, we cannot hope to obtain the results which will satisfy us in any field of cancer therapy."
years later it would appear that we can but re-echo his words, and hope that this branch of endocrinology will be raised to the status its importance merits. W. G. TAIT. Reading.
Eighteen
INTERMITTENT POSITIVE-PRESSURE RESPIRATION case of respiratory paralysis Dr. Lawes and Dr. Harries (May 26) will be carefully studied by all who might have charge of such The methods used are known to have been a case. inadequate and so the problem becomes twofold: (1) What treatment was more likely to have succeeded ? (2) Is all the necessary equipment at hand to treat a similar case should it be admitted to our own respiratory unit’? We would like to comment on some details of the treatment used and to put forward alternative suggestions. The tracheotomy tube was probably of too small a diameter, and the shape was a major cause of death.
SiR,-The very interesting
described
by
We feel that the tube designed on this unitwould have given better results. The metal linings are now made by Thackray, and Magill’s tubes in good condition are readily available ; so there is no question of special rubber tubes having perished before being wanted. We have not seen any tracheal ulceration develop whilst using these tubes, and have had the added pleasure of seeing an established ulcer heal in a few days when the first of our tubes was put into service.
The following tests probably explain why the infant had increasing carbon-dioxide tension even though the correct ventilation was apparently taking place as shown by measuring the air leaving the expiratory port of the Stott valve. A Stott valve was connected to a Radcliffe machine which had a gas-meter recording the air intake. The patient was represented by a spirometer with variable weights on the bell. Expired air was measured by another spirometer ; unidirectional valves and a pressure gauge were also used at times. Results were variable not only when using different valves but also when repeating the same test on the same valve ; but the over-all picture was consistent. Our conclusions were that air can pass from the inlet to the outlet without going to the patient. The volume leaving the Stott valve will equal that entering the machine but will be quite different from that which reaches the patient. The following are two average examples : of 600 ml. entering the machine and eventually leaving the valve, only 400 ml. reached the " patient." Similarly of 450 ml. only 300 reached the " patient." The " lost " air is thought to be compressed in the tubing during inspiration and released during expiration. In clinical use we repeatedly found that the apparent tidal volume had to be maintained in the region of 50% above the figure given on the Radford nomogram, and any reduction in this volume was quickly followed by protests from the patient. When a B.O.C. flutter-valve was submitted to the same test this discrepancy did not occur. We have found that the B.O.C. valve, being made of softer rubber, produces a 2-5 cm. water-pressure between the machine and the valve and less than 0-5 cm. water-pressure in the airway, whilst the Stott valve produces 6-8 cm. pressure between the machine and the valve and a sustained pressure of 1-5-2 cm. water-pressure in the airway. This may interfere with the gaseous exchange in the lungs. It was found, however, almost at the cost of a life, that the diaphragm of the B.O.C. valve can be inserted reversed and this should be appreciated by all who use them. Because the percentage of dead space rises as the tidal volume falls a slower rate of ventilation with increased tidal volume should have helped to reduce the carbon-dioxide 1. Hodges, R. J. H., Morley, R., O’Driscoll, W. Lancet, Jan. 7, 1956, p. 26.
B., McDonald, I.
tension in the infant. Had this not resulted, the temporary use of an efficient absorber could have been tried. Whilst a circle absorber is likely to have been effective, Sandiford’s2 to-and-fro one is almost without dead space and so should be better. With a circle absorber in use, minute volumes can be read on a gas-meter. We are in full agreement that the inflationary pattern of the Radcliffe is too prolonged. By redesigning the escapement mechanism we can now vary the wave pattern at will.
To summarise, we suggest that the infant was receiving deficient volume of air through too narrow a tube ; and from the many tests which we have done on the Stott valve during recent months we consider the performance to be very variable and that it is not reasonably possible to measure the tidal volume being delivered. One is left to control the patient largely on clinical observations. There is still room for considerable improvement in our knowledge of techniques and machinery. Is all a
possible being done to pool existing experience and knowledge which is being gained on a few isolated units which are treating in all comparatively few patients each year ?’? Portsmouth Poliomyelitis Unit.
H. B. C. SANDIFORD I. MCDONALD.
A CALCIUM-INFUSION TEST
SiR,-Dr. Nordin and Dr. Fraser, in your issue of June 2, record an experiment in which 98 patients, including " 21 patients in whom there was no reason to suspect metabolic bone disease " and " 30 patients with miscellaneous conditions in which bone disease might be suspected " were subjected to a four-hour intravenous infusion. Would it not be a good principle to state clearly in all accounts of experiments utilising human controls that the human controls are volunteers and to record the means by which their cooperation was achieved’? ANTHONY RYLE. London, N.BY.5.
***Dr. Ryle’s letter has been shown to Dr. Russell reply follows.-ED. L. SiR,ňBoth the preliminary and other subsequent tests of the intravenous procedure described were performed on volunteers amongst the research team. With all patients, agreement to the performance of the test procedure was of course obtained. Those not initially suspected of bone disease willingly gave their consent. We had every reason to believe, from personal experience, that the test was devoid of any risk, and in fact no untoward symptoms Fraser whose
or
effects followed the test in any instance.
Postgraduate Medical School, London, W.12.
RUSSELL FRASER.
ANTENATAL CARE
A concerted effort against toxaemia of pregSiR,-" " need not involve the chairmen of boards of nancy and of governors, hospital management committees," as implied by the Ministry memorandum to which you referred last week. It must involve the careful study of the prevention of Eclampsia and Pre-Eclampsia3 wherein R. H. J. Hamlin sets out the " seven steps " by means of which he eradicated eclampsia at the Women’s Hospital, Crown Street, Sydney, together with acceptance of his two points : (a) early detection by weight increase between 20th and 30th weeks; and (b) institution of a high-protein, high-vitamin, and low-carbohydrate diet at that stage. The Ministry’s memorandum pays lip service to Hamlin in Australia the practice of the Women’s Hospital, Crown Street, Sydney, described by Hamlin "), but further on states : " a routine designed to detect the smallest deviation from the normal, for example, a rising blood pressure ... slight oedema or unduly rapid weight "
2. 3.
Sandiford, H. B. C. Lancet, 1952, i, 64.
Anœsthesia, 1953, 8, 122.