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INTERMITTENT VENOUS BLOOD SAMPLING
858 the length of gestation is held constant) that:
we can
predict
The mean birth-weights of triplets, arrayed descending order of magnitude, are:
in
(1) All-male sibships should grow faster than all-female sibships of the same zygosity. (2) Dizygous twins should grow faster than monozygous (3) (4)
twins of the same sex. Girls in mixed sibships should grow faster than girls in all-female dizygous sibships. The presence of one fetus carrying the Y chromosome would enhance the growth of the whole conceptus, including that of a female twin. EVIDENCE
Information is not yet available on the birth-weights of a large unselected series of twins in whom sex and zygosity have been carefully established. However, McKeown and Record’s data 9 provide some pointers. The differences in birth-weight between the sexes diminishes as litter size increases from 0-26 lb. for singletons, to 0-10 lb. for twins, to 0-04 lb. for triplets
(same-sex sibships):
Perhaps the most striking finding is the strict alternation of the sexes with decreasing birth-weight. The single females (b), who cannot be monozygous, were only 0-03 lb. lighter than the heaviest males (a). They were 0-18 lb. heavier than the next males (c) The differences some of whom will be monozygous. between the largest (a) and the smallest (e) males (0-30 lb.), and the largest (b) and smallest (f) females (0-31 lb.) were almost the same. These findings support the hypothesis that monozygosity, where antigenic dissimilarity is least, reduces fetal growthrate ; and that the presence of the Y chromosome enhances fetal growth-rate, its effect operating on the whole conceptus. REFERENCES
Mean lengths of gestation hardly differed, between the sexes, for singletons and twins, but all-male triplets were delivered 5 days earlier than all-female .
triplets:
1. 2.
3. 4. 5.
6. 7. 8. 9. 10.
Ounsted, M., Ounsted, C. Nature, 1966, 212, 995. Ounsted, M. in Aspects of Praematurity and Dysmaturity (edited by J. H. P. Jonxis, H. K. A. Visser, J. A. Troelstra, and H. E. Stenfert Kroese), p. 167. Leiden, 1968. Ounsted, M., Ounsted, C. Nature, 1968, 220, 599. Ounsted, M. Devel. Med. Child Neurol. 1965, 7, 479. Ounsted, M. in Perinatal Factors Affecting Human Development: Pan American Health Organization, Scientific Publication no. 185, p. 60. Washington, 1969. Ounsted, M. Devel. Med. Child Neurol. 1969, 11, 693. James, D. A. J. Reprod. Fertil. 1967, 14, 265. Mittwoch, U. Nature, 1969, 221, 446. McKeown, T., Record, R. G. J. Endocr. 1952, 8, 386. Hamilton, W. J., Boyd, J. D., Mossman, H. W. Human Embryology; p. 151. Cambridge, 1962.
It is the all-female
triplets who are at variance, mixed triplets having gestation-time comparable with that for all-male triplets. This longer gestation period a
may account for the small difference in
Methods and Devices
birth-weight
between all-male and all-female triplets. All mixed sibships are dizygous, but some same-sex sibships will be monozygous. For both sexes, the infant from the mixed sibship was larger than the infant from the same-sex sibship. The difference was, however, much larger (0-43 lb.) for males than for females (0-15 Ib.). Female twins from a mixed sibship were larger even than males from an all-male sibship. This suggests that not only does the presence of a Y chromosome enhance the growth-rate of the whole conceptus, but that it is either more potent, antigenically, than autosomal variety, or that its presence is necessary for the greater autosomal variety of dizygosity to be effective in enhancing fetal growth-
INTERMITTENT VENOUS BLOOD SAMPLING ROBERT BROWN
University Department of Obstetrics and Gynœcology, Princess Mary Maternity Hospital, Newcastle upon Tyne NE2 3BD THE estimation of serum hormone levels may require the taking of serial blood-samples either by multiple venepuncture or by some system of venous cannulation. Evidence points to intermittent venepuncture affecting hormone levels-for example, growth hormone.!’2 Cannulation calls for only one venepuncture, which is much preferable to the patient. Any such system must (1) be acceptable to the patient over a period of time, and (2)
rate.
Triplets may result from multiple ovulation or from polyembryony. 10 In polyembryony, the infants will inevitably be all of the same sex, although some samesex triplets, like all mixed-sex triplets, are likely to be combinations of monozygotic and dizygotic twinning, and some will be polyzygotic. When, in a mixed sibship, one infant is of different sex from the others, this infant must be the result of multiple ovulation. mixed
Where
sibship
some
members of one sex are in a will be the result of polyembryony.
two
Fig. l.-The cannula.
859
Fig. 2.-The cannula in position.
enable the investigator to take repeated samples each of which accurately reflects the state of the peripheral venous blood. The following technique has been developed for a study which is at present being undertaken. The cannula is the Graham’Viggo ’ needle, used in anaesthesia. It consists of a winged cannula with a side arm which terminates in a diaphragm (fig. 1). The size used is 18g x 1in. (l-2x 35 mm.); the 21g has proved too small. The needle is introduced into a vein in the forearm under local anaathesia
Reviews of Books Clinical Electrocardiography and Computers Edited by CESAR A. CACERES, department of clinical engineer-
ing, George Washington Medical Center, Washington D.C., and LEONARD S. DREIFUS, Hahnneman Medical College and Hospital, Philadelphia, Pennsylvania. New York and London: Academic Press. 1970. Pp. 471.$18.50; E813s.
THE development of complex measuring and recording techniques in clinical medicine has created a major problem of analysis and interpretation for the clinician. Inevitably, therefore, computer techniques have been applied to this problem of data handling. The electrocardiogram (E.C.G.) is well suited for computer analysis; heart rate and rhythm
determined, and pattern recognition can be done simultaneously on multi-channel systems. Other variables, such as blood-pressure contours and respiratory patterns, can
be
equally amenable to computer processing, but most of the computer effort in human physiology has been directed towards the E.c.G. Much of the early work on this topic was done by Dr. Caceres and his associates, and it is fitting that he should be coeditor of this important book on the use of computers in clinical electrocardiography. An imposing list of North American contributors has been drawn from the basic and clinical sciences, public health, engineering, and physics. The material in the text is presented in four sections. The first is on instrumentation (E.c.G. machines, general and dedicated computers, and analogue-to-digital converters), and includes some general discussion on cost effectiveness and computers in hospital administration, patient-record systems, biochemical laboratories, and intensive-care units. The second section is concerned with techniques in computer programming, and deals with language, logic, lead selection, data acquisition and processing, and information storage. The first two chapters of the third section are based on conference proceedings, and cover E.c.G. standards and the influence of computers on E.C.G. measurement, clarification, and standardisation. Both contain much useful information, but superfluous and irrelevant comment should have been edited out. Other chapters deal with epidemiological and operational problems, and the section as a whole indicates the immense capability of the computer in clinical electrocardiography. The final section outlines the research potential of the are
and is kept in place with strapping (fig. 2). A large veinideally two or three times the diameter of the cannulashould be chosen. If possible the cannula should be inserted into one leg of a A-junction so that the free flow along the other leg is that which is aspirated into the needle. To keep the cannula patent between venepunctures, approximately 1 ml. of 3-8% sodium-citrate solution is injected via the diaphragm. Before taking a subsequent sample, the citrate remaining in the cannula is either aspirated and discarded or allowed to drain freely and collected on a wool swab. If the vein chosen is large enough, the flow of blood down the cannula usually suffices to obviate the necessity of applying a tourniquet and quite large samples of blood may be taken in a short time. This system has been used in over a hundred consecutive cases for a minimum of three hours each, without any difficulty. REFERENCES 1. 2.
Czarny, D., James, V. H. T., Landon, J., Greenwood, F. C. Lancet, 1968, ii, 126. Helge, H., Weber, B., Quabbe, H. J. ibid. 1969, i, 204.
computer over a wide range of cardiological problems. On the whole, the text reads well but occasionally the tortuous and complicated style of one or two contributors makes the argument difficult to follow. The book is nicely produced, but many of the illustrations could have been omitted without detriment, and the index is inadequate. But these are minor criticisms; this monograph deserves to be widely read. Public Health and
Community
Medicine
LLOYD E. BURTON, M.S., PH.D., associate professor, College of Pharmacy, University of Arizona; and HUGH HOLLINGSWORTH SMITH, M.D., M.P.H., research professor, department of microbiology and medical technology, University of Arizona. Baltimore: Williams and Wilkins. Edinburgh: E. & S. Livingstone. 1970. Pp. 561.$14.50; E7.
THIS book is intended as an undergraduate text for preclinical students, pharmacists, nurses, medical social workers, medical technologists, or medical administratorsi.e. all those studying for some kind of medical career. It is designed to steer a middle course between a general introduction and a more advanced book for graduate medical students or future specialists. The authors, therefore, presuppose little previous knowledge of the subject, though at the same time their approach is far from superficial. The book gives a comprehensive review of thirteen topics relating to public health and community medicine. After a chapter tracing the development of clinical and social medicine through nearly 6000 years of civilisation, there follows a description of the functions and structure of some national and international health organisations. A more detailed analysis of the American health system introduces one of the main themes of the book-the convergence of private medicine and public health and the increasing involvement of the U.S. Government in the provision of care. The book then turns to the more traditional concerns of public health and community medicine: methods and techniques in public-health problems, genetic and environmental factors contributing to ill-health, clinical and epidemiological aspects of certain common diseases, and methods of disease control. Later chapters deal with mental illness, the psychological and physiological effects of socioeconomic and other environmental pressures on the individual and on society, the health problems of modern society, and the preventive health services. Finally, the authors critically assess medical-care delivery in the United States and suggest alternatives. This is a practical book,
we can
predict
The mean birth-weights of triplets, arrayed descending order of magnitude, are:
in
(1) All-male sibships should grow faster than all-female sibships of the same zygosity. (2) Dizygous twins should grow faster than monozygous (3) (4)
twins of the same sex. Girls in mixed sibships should grow faster than girls in all-female dizygous sibships. The presence of one fetus carrying the Y chromosome would enhance the growth of the whole conceptus, including that of a female twin. EVIDENCE
Information is not yet available on the birth-weights of a large unselected series of twins in whom sex and zygosity have been carefully established. However, McKeown and Record’s data 9 provide some pointers. The differences in birth-weight between the sexes diminishes as litter size increases from 0-26 lb. for singletons, to 0-10 lb. for twins, to 0-04 lb. for triplets
(same-sex sibships):
Perhaps the most striking finding is the strict alternation of the sexes with decreasing birth-weight. The single females (b), who cannot be monozygous, were only 0-03 lb. lighter than the heaviest males (a). They were 0-18 lb. heavier than the next males (c) The differences some of whom will be monozygous. between the largest (a) and the smallest (e) males (0-30 lb.), and the largest (b) and smallest (f) females (0-31 lb.) were almost the same. These findings support the hypothesis that monozygosity, where antigenic dissimilarity is least, reduces fetal growthrate ; and that the presence of the Y chromosome enhances fetal growth-rate, its effect operating on the whole conceptus. REFERENCES
Mean lengths of gestation hardly differed, between the sexes, for singletons and twins, but all-male triplets were delivered 5 days earlier than all-female .
triplets:
1. 2.
3. 4. 5.
6. 7. 8. 9. 10.
Ounsted, M., Ounsted, C. Nature, 1966, 212, 995. Ounsted, M. in Aspects of Praematurity and Dysmaturity (edited by J. H. P. Jonxis, H. K. A. Visser, J. A. Troelstra, and H. E. Stenfert Kroese), p. 167. Leiden, 1968. Ounsted, M., Ounsted, C. Nature, 1968, 220, 599. Ounsted, M. Devel. Med. Child Neurol. 1965, 7, 479. Ounsted, M. in Perinatal Factors Affecting Human Development: Pan American Health Organization, Scientific Publication no. 185, p. 60. Washington, 1969. Ounsted, M. Devel. Med. Child Neurol. 1969, 11, 693. James, D. A. J. Reprod. Fertil. 1967, 14, 265. Mittwoch, U. Nature, 1969, 221, 446. McKeown, T., Record, R. G. J. Endocr. 1952, 8, 386. Hamilton, W. J., Boyd, J. D., Mossman, H. W. Human Embryology; p. 151. Cambridge, 1962.
It is the all-female
triplets who are at variance, mixed triplets having gestation-time comparable with that for all-male triplets. This longer gestation period a
may account for the small difference in
Methods and Devices
birth-weight
between all-male and all-female triplets. All mixed sibships are dizygous, but some same-sex sibships will be monozygous. For both sexes, the infant from the mixed sibship was larger than the infant from the same-sex sibship. The difference was, however, much larger (0-43 lb.) for males than for females (0-15 Ib.). Female twins from a mixed sibship were larger even than males from an all-male sibship. This suggests that not only does the presence of a Y chromosome enhance the growth-rate of the whole conceptus, but that it is either more potent, antigenically, than autosomal variety, or that its presence is necessary for the greater autosomal variety of dizygosity to be effective in enhancing fetal growth-
INTERMITTENT VENOUS BLOOD SAMPLING ROBERT BROWN
University Department of Obstetrics and Gynœcology, Princess Mary Maternity Hospital, Newcastle upon Tyne NE2 3BD THE estimation of serum hormone levels may require the taking of serial blood-samples either by multiple venepuncture or by some system of venous cannulation. Evidence points to intermittent venepuncture affecting hormone levels-for example, growth hormone.!’2 Cannulation calls for only one venepuncture, which is much preferable to the patient. Any such system must (1) be acceptable to the patient over a period of time, and (2)
rate.
Triplets may result from multiple ovulation or from polyembryony. 10 In polyembryony, the infants will inevitably be all of the same sex, although some samesex triplets, like all mixed-sex triplets, are likely to be combinations of monozygotic and dizygotic twinning, and some will be polyzygotic. When, in a mixed sibship, one infant is of different sex from the others, this infant must be the result of multiple ovulation. mixed
Where
sibship
some
members of one sex are in a will be the result of polyembryony.
two
Fig. l.-The cannula.
859
Fig. 2.-The cannula in position.
enable the investigator to take repeated samples each of which accurately reflects the state of the peripheral venous blood. The following technique has been developed for a study which is at present being undertaken. The cannula is the Graham’Viggo ’ needle, used in anaesthesia. It consists of a winged cannula with a side arm which terminates in a diaphragm (fig. 1). The size used is 18g x 1in. (l-2x 35 mm.); the 21g has proved too small. The needle is introduced into a vein in the forearm under local anaathesia
Reviews of Books Clinical Electrocardiography and Computers Edited by CESAR A. CACERES, department of clinical engineer-
ing, George Washington Medical Center, Washington D.C., and LEONARD S. DREIFUS, Hahnneman Medical College and Hospital, Philadelphia, Pennsylvania. New York and London: Academic Press. 1970. Pp. 471.$18.50; E813s.
THE development of complex measuring and recording techniques in clinical medicine has created a major problem of analysis and interpretation for the clinician. Inevitably, therefore, computer techniques have been applied to this problem of data handling. The electrocardiogram (E.C.G.) is well suited for computer analysis; heart rate and rhythm
determined, and pattern recognition can be done simultaneously on multi-channel systems. Other variables, such as blood-pressure contours and respiratory patterns, can
be
equally amenable to computer processing, but most of the computer effort in human physiology has been directed towards the E.c.G. Much of the early work on this topic was done by Dr. Caceres and his associates, and it is fitting that he should be coeditor of this important book on the use of computers in clinical electrocardiography. An imposing list of North American contributors has been drawn from the basic and clinical sciences, public health, engineering, and physics. The material in the text is presented in four sections. The first is on instrumentation (E.c.G. machines, general and dedicated computers, and analogue-to-digital converters), and includes some general discussion on cost effectiveness and computers in hospital administration, patient-record systems, biochemical laboratories, and intensive-care units. The second section is concerned with techniques in computer programming, and deals with language, logic, lead selection, data acquisition and processing, and information storage. The first two chapters of the third section are based on conference proceedings, and cover E.c.G. standards and the influence of computers on E.C.G. measurement, clarification, and standardisation. Both contain much useful information, but superfluous and irrelevant comment should have been edited out. Other chapters deal with epidemiological and operational problems, and the section as a whole indicates the immense capability of the computer in clinical electrocardiography. The final section outlines the research potential of the are
and is kept in place with strapping (fig. 2). A large veinideally two or three times the diameter of the cannulashould be chosen. If possible the cannula should be inserted into one leg of a A-junction so that the free flow along the other leg is that which is aspirated into the needle. To keep the cannula patent between venepunctures, approximately 1 ml. of 3-8% sodium-citrate solution is injected via the diaphragm. Before taking a subsequent sample, the citrate remaining in the cannula is either aspirated and discarded or allowed to drain freely and collected on a wool swab. If the vein chosen is large enough, the flow of blood down the cannula usually suffices to obviate the necessity of applying a tourniquet and quite large samples of blood may be taken in a short time. This system has been used in over a hundred consecutive cases for a minimum of three hours each, without any difficulty. REFERENCES 1. 2.
Czarny, D., James, V. H. T., Landon, J., Greenwood, F. C. Lancet, 1968, ii, 126. Helge, H., Weber, B., Quabbe, H. J. ibid. 1969, i, 204.
computer over a wide range of cardiological problems. On the whole, the text reads well but occasionally the tortuous and complicated style of one or two contributors makes the argument difficult to follow. The book is nicely produced, but many of the illustrations could have been omitted without detriment, and the index is inadequate. But these are minor criticisms; this monograph deserves to be widely read. Public Health and
Community
Medicine
LLOYD E. BURTON, M.S., PH.D., associate professor, College of Pharmacy, University of Arizona; and HUGH HOLLINGSWORTH SMITH, M.D., M.P.H., research professor, department of microbiology and medical technology, University of Arizona. Baltimore: Williams and Wilkins. Edinburgh: E. & S. Livingstone. 1970. Pp. 561.$14.50; E7.
THIS book is intended as an undergraduate text for preclinical students, pharmacists, nurses, medical social workers, medical technologists, or medical administratorsi.e. all those studying for some kind of medical career. It is designed to steer a middle course between a general introduction and a more advanced book for graduate medical students or future specialists. The authors, therefore, presuppose little previous knowledge of the subject, though at the same time their approach is far from superficial. The book gives a comprehensive review of thirteen topics relating to public health and community medicine. After a chapter tracing the development of clinical and social medicine through nearly 6000 years of civilisation, there follows a description of the functions and structure of some national and international health organisations. A more detailed analysis of the American health system introduces one of the main themes of the book-the convergence of private medicine and public health and the increasing involvement of the U.S. Government in the provision of care. The book then turns to the more traditional concerns of public health and community medicine: methods and techniques in public-health problems, genetic and environmental factors contributing to ill-health, clinical and epidemiological aspects of certain common diseases, and methods of disease control. Later chapters deal with mental illness, the psychological and physiological effects of socioeconomic and other environmental pressures on the individual and on society, the health problems of modern society, and the preventive health services. Finally, the authors critically assess medical-care delivery in the United States and suggest alternatives. This is a practical book,