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FLUID REQUIREMENTS IN ASIATIC CHOLERA
1114
Letters to the Editor
simple and considerably more accurate method determining fluid requirements and monitoring fluid replacement in all forms of volume loss. sure as a
of FLUID REQUIREMENTS IN ASIATIC CHOLERA
SiR,—The article by Dr. Carpenter and his colleagues the clinical assessment of cholera patients (April 3) is an important contribution to the practical management of these difficult cases. But it is surprising that the patients required an average of only 4-1litres of intravenous fluids to rectify their condition since fluid-loss in severe cholera may be up to 15 litres daily.l Indeed, 60 litres of intravenous fluid may be needed in 5 days, and potassium losses can be 20% of the body stores.2 It has been suggested that 20 litres of fluid per patient should be allowed in anticipatihg fluid requirements for cholera patients.3 The relatively small amount of fluid needed by Dr. Carpenter’s patients therefore suggests that the severity of their cholera was only moderate (despite systemic blood-pressures below 80 mm. Hg). It would be interesting to know the quality of the radial pulses of the 42 patients before treatment was
W. Z. YAHR J. S. KRAKAUER.
Morrisania City Hospital, Montefiore Hospital and Medical Center, New York.
on
started. Department of Tropical Medicine, Liverpool School of Tropical Medicine, Liverpool, 3.
H. ALISTAIR REID.
SIR,-In replacing fluid-losses in Asiatic cholera, and his colleagues emphasise the radial pulse and the appearance of the neck veins " as accurate clinical guides to fluid replacement. The authors are to be commended for their most impressive results. Dr. "
Carpenter quality of the
agreeing that the indices reported are simple and omnipresent, we believe they are too qualitative, are dependent upon more than the single variable of hypovolsmia, and demand extremely sensitive fingertips for reliable palpation. We have been particularly interested in all forms of volume disturbances, and have observed that the level of the intraluminal pressure of the intrathoracic vena cava (so-called central venous pressure) provides a reliable indirect measureWhile
of the extracellular volume. The central venous pressure measures directly the mean systemic pressure, which is the resultant of the variables of intravascular volume, interstitial volume, vasomotion, and resistance and capacitance of the systemic circulation. It is most influenced by changes in volume. The central venous pressure integrates these variables with cardiac function (Starling’s law of the heart), and thereby becomes an extremely accurate quantitative index of effective extracellular volume. In addition, it is probably the only accurate clinical method of determining dynamic volume loss, once the static volume debt has been replaced. With the utilisation of the central venous pressure, we have been impressed with the observation that the average static fluid debt in patients with non-haemorrhagic volume loss is approximately 25-30% of the predicted extracellular volume. We do not believe it fortuitous that the mean static debt in the series of Dr. Carpenter and his colleagues was 4-1litres, or 29% of the predicted extracellular volume (based upon a 70 kg. male of lean body habitus). We have also observed that patients with a 25% loss of extracellular volume from desalting water loss caused in various
PATHOGENESIS OF GASTRIC ULCERATION SIR,-It seems inconceivable that Professor du Plessis (May 8) can be correct in his thesis of the pathogenesis of
gastric ulceration. In my
practice it has been routine since 1956 to heal gastric ulceration, evidently permanently, by an operation which, if it does not encourage duodenal reflux, at least makes it perfectly feasible. I refer, of course, to the Finney pyloroplasty component of the operation, and it is my experience that bile is usually present in gastric postoperative test-meal fractions (in a majority of fractions in 69 % of over 50 cases), although gastroscopically the appearances within the stomach are normal and the mucosa looks quiet and not inflamed. Dragstedtis probably correct in his hypothesis that gastric stasis leading to excessive amounts of gastrin " juice is a factor; in my patients it has been apparent that healing of gastric ulcers has been delayed a few weeks longer than expected in patients with severe gastric atony after vagus resection, with consequent slow emptying of the stomach. The ulcers have always healed within ten weeks, nevertheless, as gastric tone recovers and gastric emptying becomes more efficient. Hypersecretion is almost certainly an important factor as well; Miller et a1.2 showed that uropeptic activity was greatly increased in gastric ulceration, as in duodenal ulcerationsuggesting that pepsin secretion is increased in these stomachs. This is perhaps the most important reason why vagus resection "
is essential in these
cases.
My experience, therefore, suggests that with efficient vagus resection duodenal reflux has no harmful effect on gastric mucosa, provided that the stomach empties at a reasonably normal rate, as in Finney pyloroplasty and vagus resection. Gastric ulcers always heal and do not seem to recur.
W. GARDEN HENDRY.
ment
usually normotensive. This appreciable loss, repre3-5 litres of total extracellular volume, 2-8 litres of senting interstitial volume, and 700 ml. of plasma volume, may easily go undetected by the indices of Dr. Carpenter and his colleagues. In these instances the central venous pressure is zero, indicative of the occult hypovolxmia, while the standard blood-pressure and pulse-rate are usually normal. ways
are
We should like 1. 2. 3.
to recommend the central venous presPhillips, R. A. Bull. Wld Hlth Org. 1963, 28, 297. Phillips, R. A. Fedn Proc. Fedn Am. Socs exp. Biol. 1964, 23, 705. Wallace, C. K., Fable, A. E., Mangubat, O., Velasco, E., Junio, C., Phillips, R.A. Bull. Wld Hlth Org. 1964, 30, 795.
"
OBJECTIVE
"
EXAMINATIONS FOR MEDICAL STUDENTS
SIR,-The article by Dr. Anderson and co-workers (May 1) prompts us to report our own experiences in this field. For the past year all 68 candidates for the second M.B. pharmacology examination at St. Thomas’s Hospital Medical School have answered a multiple-choice paper, immediately after the standard essay paper; the results were not included in the examination because we felt the need to gain experience from a pilot experiment. Both recognition and recall questions were set. One of the types of recognition questions was that described by Dr. Anderson and his colleagues; the other, described by Hubbard and Clemans,3 consisted of an assertion and a reason for the assertion. There are five possible answers to such questions: (1) assertion and reason true, and reason a correct explanation of the assertion; (2) assertion and reason true, but reason not a correct explanation of the assertion; (3) assertion true, reason false; (4) assertion false, reason true; and (5) both assertion and reason false. An example of such a question, the answer to which is (2), is adrenaline increases the heart-rate, because it activates alpha-receptors ". The overall correlation-coefficient (r) between the results of the examination and of the multiple-choice paper was 0-72. Since they may test different abilities, better agreement between them is not to be expected. Comparison between the perform"
1. Dragstedt, L. R. Ann. N.Y. Acad. Sci. 1962, 99, 190. 2. Miller, L. L., Segal, H. L., Plumb, E. J. Gastroenterology, 1957, 33, 557. 3. Hubbard, J. P., Clemans, W. V. Multiple-choice Examinations in Medicine; p. 78. London, 1961.
Letters to the Editor
simple and considerably more accurate method determining fluid requirements and monitoring fluid replacement in all forms of volume loss. sure as a
of FLUID REQUIREMENTS IN ASIATIC CHOLERA
SiR,—The article by Dr. Carpenter and his colleagues the clinical assessment of cholera patients (April 3) is an important contribution to the practical management of these difficult cases. But it is surprising that the patients required an average of only 4-1litres of intravenous fluids to rectify their condition since fluid-loss in severe cholera may be up to 15 litres daily.l Indeed, 60 litres of intravenous fluid may be needed in 5 days, and potassium losses can be 20% of the body stores.2 It has been suggested that 20 litres of fluid per patient should be allowed in anticipatihg fluid requirements for cholera patients.3 The relatively small amount of fluid needed by Dr. Carpenter’s patients therefore suggests that the severity of their cholera was only moderate (despite systemic blood-pressures below 80 mm. Hg). It would be interesting to know the quality of the radial pulses of the 42 patients before treatment was
W. Z. YAHR J. S. KRAKAUER.
Morrisania City Hospital, Montefiore Hospital and Medical Center, New York.
on
started. Department of Tropical Medicine, Liverpool School of Tropical Medicine, Liverpool, 3.
H. ALISTAIR REID.
SIR,-In replacing fluid-losses in Asiatic cholera, and his colleagues emphasise the radial pulse and the appearance of the neck veins " as accurate clinical guides to fluid replacement. The authors are to be commended for their most impressive results. Dr. "
Carpenter quality of the
agreeing that the indices reported are simple and omnipresent, we believe they are too qualitative, are dependent upon more than the single variable of hypovolsmia, and demand extremely sensitive fingertips for reliable palpation. We have been particularly interested in all forms of volume disturbances, and have observed that the level of the intraluminal pressure of the intrathoracic vena cava (so-called central venous pressure) provides a reliable indirect measureWhile
of the extracellular volume. The central venous pressure measures directly the mean systemic pressure, which is the resultant of the variables of intravascular volume, interstitial volume, vasomotion, and resistance and capacitance of the systemic circulation. It is most influenced by changes in volume. The central venous pressure integrates these variables with cardiac function (Starling’s law of the heart), and thereby becomes an extremely accurate quantitative index of effective extracellular volume. In addition, it is probably the only accurate clinical method of determining dynamic volume loss, once the static volume debt has been replaced. With the utilisation of the central venous pressure, we have been impressed with the observation that the average static fluid debt in patients with non-haemorrhagic volume loss is approximately 25-30% of the predicted extracellular volume. We do not believe it fortuitous that the mean static debt in the series of Dr. Carpenter and his colleagues was 4-1litres, or 29% of the predicted extracellular volume (based upon a 70 kg. male of lean body habitus). We have also observed that patients with a 25% loss of extracellular volume from desalting water loss caused in various
PATHOGENESIS OF GASTRIC ULCERATION SIR,-It seems inconceivable that Professor du Plessis (May 8) can be correct in his thesis of the pathogenesis of
gastric ulceration. In my
practice it has been routine since 1956 to heal gastric ulceration, evidently permanently, by an operation which, if it does not encourage duodenal reflux, at least makes it perfectly feasible. I refer, of course, to the Finney pyloroplasty component of the operation, and it is my experience that bile is usually present in gastric postoperative test-meal fractions (in a majority of fractions in 69 % of over 50 cases), although gastroscopically the appearances within the stomach are normal and the mucosa looks quiet and not inflamed. Dragstedtis probably correct in his hypothesis that gastric stasis leading to excessive amounts of gastrin " juice is a factor; in my patients it has been apparent that healing of gastric ulcers has been delayed a few weeks longer than expected in patients with severe gastric atony after vagus resection, with consequent slow emptying of the stomach. The ulcers have always healed within ten weeks, nevertheless, as gastric tone recovers and gastric emptying becomes more efficient. Hypersecretion is almost certainly an important factor as well; Miller et a1.2 showed that uropeptic activity was greatly increased in gastric ulceration, as in duodenal ulcerationsuggesting that pepsin secretion is increased in these stomachs. This is perhaps the most important reason why vagus resection "
is essential in these
cases.
My experience, therefore, suggests that with efficient vagus resection duodenal reflux has no harmful effect on gastric mucosa, provided that the stomach empties at a reasonably normal rate, as in Finney pyloroplasty and vagus resection. Gastric ulcers always heal and do not seem to recur.
W. GARDEN HENDRY.
ment
usually normotensive. This appreciable loss, repre3-5 litres of total extracellular volume, 2-8 litres of senting interstitial volume, and 700 ml. of plasma volume, may easily go undetected by the indices of Dr. Carpenter and his colleagues. In these instances the central venous pressure is zero, indicative of the occult hypovolxmia, while the standard blood-pressure and pulse-rate are usually normal. ways
are
We should like 1. 2. 3.
to recommend the central venous presPhillips, R. A. Bull. Wld Hlth Org. 1963, 28, 297. Phillips, R. A. Fedn Proc. Fedn Am. Socs exp. Biol. 1964, 23, 705. Wallace, C. K., Fable, A. E., Mangubat, O., Velasco, E., Junio, C., Phillips, R.A. Bull. Wld Hlth Org. 1964, 30, 795.
"
OBJECTIVE
"
EXAMINATIONS FOR MEDICAL STUDENTS
SIR,-The article by Dr. Anderson and co-workers (May 1) prompts us to report our own experiences in this field. For the past year all 68 candidates for the second M.B. pharmacology examination at St. Thomas’s Hospital Medical School have answered a multiple-choice paper, immediately after the standard essay paper; the results were not included in the examination because we felt the need to gain experience from a pilot experiment. Both recognition and recall questions were set. One of the types of recognition questions was that described by Dr. Anderson and his colleagues; the other, described by Hubbard and Clemans,3 consisted of an assertion and a reason for the assertion. There are five possible answers to such questions: (1) assertion and reason true, and reason a correct explanation of the assertion; (2) assertion and reason true, but reason not a correct explanation of the assertion; (3) assertion true, reason false; (4) assertion false, reason true; and (5) both assertion and reason false. An example of such a question, the answer to which is (2), is adrenaline increases the heart-rate, because it activates alpha-receptors ". The overall correlation-coefficient (r) between the results of the examination and of the multiple-choice paper was 0-72. Since they may test different abilities, better agreement between them is not to be expected. Comparison between the perform"
1. Dragstedt, L. R. Ann. N.Y. Acad. Sci. 1962, 99, 190. 2. Miller, L. L., Segal, H. L., Plumb, E. J. Gastroenterology, 1957, 33, 557. 3. Hubbard, J. P., Clemans, W. V. Multiple-choice Examinations in Medicine; p. 78. London, 1961.