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DETERMINING PLASMA-RENIN ACTIVITY
840 and died 18 hours later, at which time his plasma-lithium level had risen to 3-2 meq. per litre. Lithium is evenly distributed in the water phase of the body; it seems that successful removal by ha:modialysis will require frequent or continuous dialysis over a long period to ensure the reduction of toxic intracellular levels and the elimination of " reserves " in bone. J. B. HAWKINS East Birmingham Hospital, P. R. DORKEN. Birmingham 9.
TREATMENT OF HYDROCEPHALUS
SIR,-In a leading article (Jan. 25, p. 191) you point out that obstruction of the flow in the venous catheter is one of the most important reasons for malfunction of the shunt, and note the difficulty in introducing a new catheter. In patients in whom it is not possible to introduce a longer catheter into the internal jugular vein, surgeons have resorted to using the same vessel on the opposite side or to thoracotomy-neither is a good method. Consequently it has seemed important to develop a method for easy replacement of the catheter in these cases. The common use of percutaneous subclavian-vein catheterisation for intravenous infusion made it seem natural to try this route.
Method.-The venous catheter is introduced into the subIn clavian vein by percutaneous supraclavicular puncture. a supine patient this is done in the angle between the clavicle and the lateral margin of the sterno-mastoid muscle. After penetrating the skin, the needle is directed 45° medially and 10° ventrally.1 To prevent air embolism and pneumothorax the patient’s head is now lowered and a syringe is connected to the needle. The vessel is reached at a depth of 1 -5-4 cm. in less in children. When venous blood is flowing freely adults, a Holter catheter, B type, connected to a pressure recorder, is DETAILS
OF
8
PATIENTS
CATHETERISED
VIA
THE
SUBCLAVIAN
VEIN
DETERMINING PLASMA-RENIN ACTIVITY SIR, The letters of Dr. Ledingham and Dr. Lee, and Dr. Boyd and his colleagues (March 8, p. 533) give me an opportunity to support the confidence of Dr. Boyd and his colleagues in the validity of the radioimmunoassay of angiotensin I and II. I also have developed in parallel a method for radioimmunoassay of angiotensin I,1 as have Haber et a1.2 and Hollemans et al.3 My colleagues followed with some modifications and simplifications the same tactical approach as for angiotensin 11.4Since the present sensitivity of the method is 0-3 ng. of angiotensin I, the generation of this decapeptide can be followed during incubation over short periods of time in samples of human plasma as small as 1 ml. The standard error of the mean value in 8 samples was ±2-1%. Sensitivity and precision are such that multiple determinations can be made at short intervals in the same patient without the nuisance of drawing a large amount of blood each time. The possibility of making simultaneous determinations in many plasma-samples is a further advantage of the method. The problem of inhibition of the converting enzyme by edetic acid (E.D.T.A.) raised in the letters had always worried workers in this field. We had originally chosen for the assay of angiotensin II a concentration of E.D.T.A. which, according to Skeggs et al.,6 was no longer inhibitory, and actually we did observe the generation of angiotensin II during incubation.5 However, we found out with more experience that in some plasmas there was partial or complete inhibition of the converting enzyme even at that concentration of E.D.T.A. The difficulty in finding the proper conditions satisfying full converting-enzyme activity while assuring complete block of angiotensinase, led me, as well as Dr. Boyd and his colleagues,’7 Haber et al.,2 and Hollemans et al.,3 to the development of an immunoassay of angiotensin I in order to measure the direct product of renin under conditions completely preventing both angiotensinase and converting-enzyme activity. The radioimmunoassay of angiotensin II is still valid for the determination of circulating angiotensin II if one has an antiserum with a high association constant (the titre being much less important in this regard). Obviously only more experience with these new methods will prove their final validity, but for the moment they seem very promising and reliable. Laboratoire de Physiopathologie Clinique, Hôpital Cantonal, Geneva, Switzerland.
advanced through the needle until the recorder shows a ventricle pressure wave.23 The needle is then withdrawn and the catheter retracted to the auricle. The catheter should not be retracted with the needle in situ, in case it might be cut off. A piece of A-type catheter is inserted between the valve and the thinner B-type catheter to prevent kinking on the neck. Results.-8 patients have been operated upon by this technique (see accompanying table). The group contains no infants, for it seems desirable first to refine the method and evaluate the results and possible complications. I have, however, in another connection shown that it is possible to puncture and catheterise the subclavian vein in neonates. I believe that this is a good alternative method when it is difficult or inadvisable to introduce a venous catheter through the jugular vein. Whether this technique also has any advantage over current ones for primary shunt operations is not yet established. Department of Neurosurgery, Regionsjukhuset, Linköping, Sweden. 1. 2. 3.
LENNART RABOW.
Yoffe, D. Lancet, 1965, ii, 614. Järpe, S., Hebbe, B. ibid. 1966, ii, 970. Järpe, S., Hebbe, B., Jeppsson, S. Rabow, L., Rådberg, C. Acta chir. scand. 1969, 135, 121.
M. B. VALLOTTON.
DIGITAL DERMATOGLYPHICS AND BLOOD-GROUPS SIR,-Dr. Otto and Dr. Bozóti have reported8a highly significant association between the ABO blood-groups and the digital pattern of whorls, loops, and arches. However, they have assumed in their analysis that the patterns on the fingers of the same individual are not correlated. This is known not to be true.9 If all the fingers of each person always showed the same pattern, then Z2 would be 1.55 (2 D.F., p= 0-461), not 15.5 (2 D.F., p= 0-000433) as given by Dr. Otto and Dr. Bozóti. Since the patterns on different fingers are not completely correlated, the probability lies between these two values. A complete analysis is needed before an association between Vallotton, M. B. Clin. Res. (abstract, in the press). Haber, E., Kroener, Th., Page, L. B. Circulation, 1968, 38, suppl. 6, p. 91 (abstract). 3. Hollemans, H. J. G., Van der Meer, J., Kloosterziel, W. Clin. chim. Acta, 1969, 23, 7. 4. Vallotton, M. B., Page, L. B., Haber, E. Nature, Lond. 1967, 215, 714. 5. Haber, E., Vallotton, M. B., Kimura, A., Page, L. B. Excerpta med. int. Congr. Ser. 1968, no. 161, p. 359. 6. Skeggs, L. T., Kahn, J. R., Shumway, N. P. J. exp. Med. 1956, 103, 295. 7. Boyd, G. W., Adamson, A. R., Fitz, A. E., Peart, W. S. Lancet, Feb. 1, 1969, p. 213. 8. Otto, P. A., Bozóti, M. M. Lancet, 1968, ii, 1250. 9. Holt, S. B. Ann. Eugen. 1951, 16, 287. 1. 2.
TREATMENT OF HYDROCEPHALUS
SIR,-In a leading article (Jan. 25, p. 191) you point out that obstruction of the flow in the venous catheter is one of the most important reasons for malfunction of the shunt, and note the difficulty in introducing a new catheter. In patients in whom it is not possible to introduce a longer catheter into the internal jugular vein, surgeons have resorted to using the same vessel on the opposite side or to thoracotomy-neither is a good method. Consequently it has seemed important to develop a method for easy replacement of the catheter in these cases. The common use of percutaneous subclavian-vein catheterisation for intravenous infusion made it seem natural to try this route.
Method.-The venous catheter is introduced into the subIn clavian vein by percutaneous supraclavicular puncture. a supine patient this is done in the angle between the clavicle and the lateral margin of the sterno-mastoid muscle. After penetrating the skin, the needle is directed 45° medially and 10° ventrally.1 To prevent air embolism and pneumothorax the patient’s head is now lowered and a syringe is connected to the needle. The vessel is reached at a depth of 1 -5-4 cm. in less in children. When venous blood is flowing freely adults, a Holter catheter, B type, connected to a pressure recorder, is DETAILS
OF
8
PATIENTS
CATHETERISED
VIA
THE
SUBCLAVIAN
VEIN
DETERMINING PLASMA-RENIN ACTIVITY SIR, The letters of Dr. Ledingham and Dr. Lee, and Dr. Boyd and his colleagues (March 8, p. 533) give me an opportunity to support the confidence of Dr. Boyd and his colleagues in the validity of the radioimmunoassay of angiotensin I and II. I also have developed in parallel a method for radioimmunoassay of angiotensin I,1 as have Haber et a1.2 and Hollemans et al.3 My colleagues followed with some modifications and simplifications the same tactical approach as for angiotensin 11.4Since the present sensitivity of the method is 0-3 ng. of angiotensin I, the generation of this decapeptide can be followed during incubation over short periods of time in samples of human plasma as small as 1 ml. The standard error of the mean value in 8 samples was ±2-1%. Sensitivity and precision are such that multiple determinations can be made at short intervals in the same patient without the nuisance of drawing a large amount of blood each time. The possibility of making simultaneous determinations in many plasma-samples is a further advantage of the method. The problem of inhibition of the converting enzyme by edetic acid (E.D.T.A.) raised in the letters had always worried workers in this field. We had originally chosen for the assay of angiotensin II a concentration of E.D.T.A. which, according to Skeggs et al.,6 was no longer inhibitory, and actually we did observe the generation of angiotensin II during incubation.5 However, we found out with more experience that in some plasmas there was partial or complete inhibition of the converting enzyme even at that concentration of E.D.T.A. The difficulty in finding the proper conditions satisfying full converting-enzyme activity while assuring complete block of angiotensinase, led me, as well as Dr. Boyd and his colleagues,’7 Haber et al.,2 and Hollemans et al.,3 to the development of an immunoassay of angiotensin I in order to measure the direct product of renin under conditions completely preventing both angiotensinase and converting-enzyme activity. The radioimmunoassay of angiotensin II is still valid for the determination of circulating angiotensin II if one has an antiserum with a high association constant (the titre being much less important in this regard). Obviously only more experience with these new methods will prove their final validity, but for the moment they seem very promising and reliable. Laboratoire de Physiopathologie Clinique, Hôpital Cantonal, Geneva, Switzerland.
advanced through the needle until the recorder shows a ventricle pressure wave.23 The needle is then withdrawn and the catheter retracted to the auricle. The catheter should not be retracted with the needle in situ, in case it might be cut off. A piece of A-type catheter is inserted between the valve and the thinner B-type catheter to prevent kinking on the neck. Results.-8 patients have been operated upon by this technique (see accompanying table). The group contains no infants, for it seems desirable first to refine the method and evaluate the results and possible complications. I have, however, in another connection shown that it is possible to puncture and catheterise the subclavian vein in neonates. I believe that this is a good alternative method when it is difficult or inadvisable to introduce a venous catheter through the jugular vein. Whether this technique also has any advantage over current ones for primary shunt operations is not yet established. Department of Neurosurgery, Regionsjukhuset, Linköping, Sweden. 1. 2. 3.
LENNART RABOW.
Yoffe, D. Lancet, 1965, ii, 614. Järpe, S., Hebbe, B. ibid. 1966, ii, 970. Järpe, S., Hebbe, B., Jeppsson, S. Rabow, L., Rådberg, C. Acta chir. scand. 1969, 135, 121.
M. B. VALLOTTON.
DIGITAL DERMATOGLYPHICS AND BLOOD-GROUPS SIR,-Dr. Otto and Dr. Bozóti have reported8a highly significant association between the ABO blood-groups and the digital pattern of whorls, loops, and arches. However, they have assumed in their analysis that the patterns on the fingers of the same individual are not correlated. This is known not to be true.9 If all the fingers of each person always showed the same pattern, then Z2 would be 1.55 (2 D.F., p= 0-461), not 15.5 (2 D.F., p= 0-000433) as given by Dr. Otto and Dr. Bozóti. Since the patterns on different fingers are not completely correlated, the probability lies between these two values. A complete analysis is needed before an association between Vallotton, M. B. Clin. Res. (abstract, in the press). Haber, E., Kroener, Th., Page, L. B. Circulation, 1968, 38, suppl. 6, p. 91 (abstract). 3. Hollemans, H. J. G., Van der Meer, J., Kloosterziel, W. Clin. chim. Acta, 1969, 23, 7. 4. Vallotton, M. B., Page, L. B., Haber, E. Nature, Lond. 1967, 215, 714. 5. Haber, E., Vallotton, M. B., Kimura, A., Page, L. B. Excerpta med. int. Congr. Ser. 1968, no. 161, p. 359. 6. Skeggs, L. T., Kahn, J. R., Shumway, N. P. J. exp. Med. 1956, 103, 295. 7. Boyd, G. W., Adamson, A. R., Fitz, A. E., Peart, W. S. Lancet, Feb. 1, 1969, p. 213. 8. Otto, P. A., Bozóti, M. M. Lancet, 1968, ii, 1250. 9. Holt, S. B. Ann. Eugen. 1951, 16, 287. 1. 2.