- Email: [email protected]
PLATELET AGGREGATION DURING MAJOR OPERATIONS
316
Many of the preparations listed were developed as research standards and are already widely used. Biological activity was the main criterion employed in their choice, but immunoassays (frequently more sensitive and cheaper than bioassays) will generally be used for clinical purposes. The clinical significance of immunoassay results requires expert assessment, bearing in mind that biological activity does not necessarily reside in the part(s) of the hormone measured in an immunoassay system. In many cases it is already clear that further research is needed to decide which molecular form it is most useful to estimate for clinical purposes (e.g., precursor, free peptide, proteinbound, or metabolic product). If such research reveals a need for additional reference materials, steps will be taken to
provide them.
Division of Biological Standards, National Institute for Medical Research, Mill Hill, London N.W.7.
D. R. BANGHAM D. H. CALAM P. MARY COTES J. A. PARSONS C. J. ROBINSON.
PRICE OF TEXTBOOKS
SIR,-Dr. Wilson’s letter on expensive textbooks (Jan. 15, p. 150) prompts me to point out that, although E28 may be a high price for a book, British undergraduate and postgraduate students may still consider themselves much luckier than their colleagues abroad. The 3rd edition of Goodman and Gillman’s Pharmacological Basis of Therapeutics (1965) cost t10.50 in England. Its Italian translation appeared in 1970 and sold for 55,000 lira (that is, about E36.60). Robbins’ Pathology, E8.75 in the U.K., is available in Italian at 36,000 lira (that is, about E24). Textbooks by Italian authors cost about the same, if not more. Via Bezzecca 29, 22053 Lecco,
Italy.
A. E. M. ATTANASIO.
PLATELET AGGREGATION DURING OPERATIONS
MAJOR
SIR,-Dr. Caul 37 children with
(Jan. 15, p. 143) reports that 14 out of cyanotic congenital heart-disease had impaired platelet aggregation. Since the impairment of aggregation correlated with the degree of hypoxoemia (in the 14 or the 37 was not clear) she implies that a causal relationship may exist. She then suggests that transient episodes of hypoxxmia may also account for the refractory state in platelet aggregability during and soon after major operations. Although it is impossible to exclude transient hypoxaemia we think this most unlikely for the following reasons. Serial arterial blood-gas tensions were monitored every 30 minutes by one of us (J. H.) in a number of patients undergoing strictly comparable ansesthesia and surgery. The highest oxygen tension measured was 435 mm. Hg and it never fell below 128. There are, after all, a number of other reports of platelets becoming temporarily refractory in situations in which it was impossible for hypoxasmia to occur.2-5 We suggested that A.D.P. might have caused the refractory state,l but not that it was " liberated from the platelets ". It could just as well have come from tissue damage or from damaged red-cells as from the platelets. At any rate during and for a few hours postoperatively there 1. 2. 3.
4. 5.
O’Brien, J. R., Etherington, M., Jamieson, S. Lancet, 1971, ii, 741. Bushfield, D., Tomich, E. G. Nature, 1967, 214, 1360. Hornstra, G. Br. J. Hœmat. 1970, 19, 231. Coller, B. S., Zucker, M. B. Proc. Soc. exp. Biol. Med. 1971, 136, 769. Ardlie, N. G., Perry, D. W., Packham, M. A., Mustard, J. F. ibid. p. 1021.
emerges the complicated pattern of platelets which are initially normally responsive. Presumably they are then exposed to A.D.P. locally and become transiently more responsive. Thereafter, in the general circulation, they are found to be refractory, only to return to the preoperative level or even to an increased reponsiveness by the next day. Portsmouth and Isle of Wight Area
Pathology Service, Central Laboratory, St. Mary’s General Hospital, Portsmouth PO3 6AG.
J. R. O’BRIEN R. C. NAINBY-LUXMOORE A. G. LARSEN J. HENVILLE.
DEVELOPMENTAL PÆDIATRICS SIR,-Interception of letters may be a somewhat chancy means of discovering misconceptions. The letter from Ronnie to Tim (Jan. 15, p. 139) contains the misconceived statement that I believe that developmental pxdiatrics
developmental assessment. Development is implicit in childhood, and many, including biologists, teachers, and psychologists, as well as paediatricians, are concerned with it. A knowledge of child development is as fundamental to pxdiatrics as is anatomy to surgery or pharmacology to therapeutics, but developmental assessment is no more the totality of developmental paediatrics than are anatomy and pharmacology totalities of the clinical disciplines to which they relate. Developmental assessment both of the normal and the abnormal, disorders of development, and diseases which disturb development all come within the ambit of developmental pxdiatrics. If it is argued that, with this concept of the term, developmental paediatrics embraces all of pxdiatrics. This is not so. Reference to any standard paediatric textbook will show that a great deal of the diagnosis and management of disease and disability in childhood is encompassed without reference to development. Developmental assessment is one of the tools of the paediatric trade. It is a tool which has been fashioned only recently and is yet far from perfect; but it is an important tool, and there must be a good deal of emphasis at this time on training in its use, particularly for those whose
means
medical education antedated its introduction. Even in current medical curricula, training in developmental assessment is probably inadequate. Within the context of medical practice it would be unfortunate if those who devote their lives to child development, particularly to developmental assessment, became unduly separated from the generality of doctors who look after children, if their methods, their language, and the unlimited multiplication of their techniques created a discipline of proportions so forbidding and aspect so esoteric that the ordinary doctor was afraid to involve himself in it. University Department of Child Life and Health, 17 Hatton Place,
Edinburgh
EH9 1UW.
J. O. FORFAR.
SIR,-Dr. Meadow asks (Dec. 25, p. 1430) what is to be done about the confusion of tests available for the assessment of development in children. We suggest that the basic tool needed is the Griffiths Mental Development Scale. This extends from the first few weeks to the end of the eighth year. It provides not only a general quotient of overall progress but also a detailed profile of mental age, locomotor development, personal/social development, speech, hearing, eye/hand coordination, and performance; and for the later years it provides a subscale called practical reasoning. The scale is based largely on observations of play and of the child’s self-imposed tasks. Testing requires much patience, and not all doctors have this aptitude; but
Many of the preparations listed were developed as research standards and are already widely used. Biological activity was the main criterion employed in their choice, but immunoassays (frequently more sensitive and cheaper than bioassays) will generally be used for clinical purposes. The clinical significance of immunoassay results requires expert assessment, bearing in mind that biological activity does not necessarily reside in the part(s) of the hormone measured in an immunoassay system. In many cases it is already clear that further research is needed to decide which molecular form it is most useful to estimate for clinical purposes (e.g., precursor, free peptide, proteinbound, or metabolic product). If such research reveals a need for additional reference materials, steps will be taken to
provide them.
Division of Biological Standards, National Institute for Medical Research, Mill Hill, London N.W.7.
D. R. BANGHAM D. H. CALAM P. MARY COTES J. A. PARSONS C. J. ROBINSON.
PRICE OF TEXTBOOKS
SIR,-Dr. Wilson’s letter on expensive textbooks (Jan. 15, p. 150) prompts me to point out that, although E28 may be a high price for a book, British undergraduate and postgraduate students may still consider themselves much luckier than their colleagues abroad. The 3rd edition of Goodman and Gillman’s Pharmacological Basis of Therapeutics (1965) cost t10.50 in England. Its Italian translation appeared in 1970 and sold for 55,000 lira (that is, about E36.60). Robbins’ Pathology, E8.75 in the U.K., is available in Italian at 36,000 lira (that is, about E24). Textbooks by Italian authors cost about the same, if not more. Via Bezzecca 29, 22053 Lecco,
Italy.
A. E. M. ATTANASIO.
PLATELET AGGREGATION DURING OPERATIONS
MAJOR
SIR,-Dr. Caul 37 children with
(Jan. 15, p. 143) reports that 14 out of cyanotic congenital heart-disease had impaired platelet aggregation. Since the impairment of aggregation correlated with the degree of hypoxoemia (in the 14 or the 37 was not clear) she implies that a causal relationship may exist. She then suggests that transient episodes of hypoxxmia may also account for the refractory state in platelet aggregability during and soon after major operations. Although it is impossible to exclude transient hypoxaemia we think this most unlikely for the following reasons. Serial arterial blood-gas tensions were monitored every 30 minutes by one of us (J. H.) in a number of patients undergoing strictly comparable ansesthesia and surgery. The highest oxygen tension measured was 435 mm. Hg and it never fell below 128. There are, after all, a number of other reports of platelets becoming temporarily refractory in situations in which it was impossible for hypoxasmia to occur.2-5 We suggested that A.D.P. might have caused the refractory state,l but not that it was " liberated from the platelets ". It could just as well have come from tissue damage or from damaged red-cells as from the platelets. At any rate during and for a few hours postoperatively there 1. 2. 3.
4. 5.
O’Brien, J. R., Etherington, M., Jamieson, S. Lancet, 1971, ii, 741. Bushfield, D., Tomich, E. G. Nature, 1967, 214, 1360. Hornstra, G. Br. J. Hœmat. 1970, 19, 231. Coller, B. S., Zucker, M. B. Proc. Soc. exp. Biol. Med. 1971, 136, 769. Ardlie, N. G., Perry, D. W., Packham, M. A., Mustard, J. F. ibid. p. 1021.
emerges the complicated pattern of platelets which are initially normally responsive. Presumably they are then exposed to A.D.P. locally and become transiently more responsive. Thereafter, in the general circulation, they are found to be refractory, only to return to the preoperative level or even to an increased reponsiveness by the next day. Portsmouth and Isle of Wight Area
Pathology Service, Central Laboratory, St. Mary’s General Hospital, Portsmouth PO3 6AG.
J. R. O’BRIEN R. C. NAINBY-LUXMOORE A. G. LARSEN J. HENVILLE.
DEVELOPMENTAL PÆDIATRICS SIR,-Interception of letters may be a somewhat chancy means of discovering misconceptions. The letter from Ronnie to Tim (Jan. 15, p. 139) contains the misconceived statement that I believe that developmental pxdiatrics
developmental assessment. Development is implicit in childhood, and many, including biologists, teachers, and psychologists, as well as paediatricians, are concerned with it. A knowledge of child development is as fundamental to pxdiatrics as is anatomy to surgery or pharmacology to therapeutics, but developmental assessment is no more the totality of developmental paediatrics than are anatomy and pharmacology totalities of the clinical disciplines to which they relate. Developmental assessment both of the normal and the abnormal, disorders of development, and diseases which disturb development all come within the ambit of developmental pxdiatrics. If it is argued that, with this concept of the term, developmental paediatrics embraces all of pxdiatrics. This is not so. Reference to any standard paediatric textbook will show that a great deal of the diagnosis and management of disease and disability in childhood is encompassed without reference to development. Developmental assessment is one of the tools of the paediatric trade. It is a tool which has been fashioned only recently and is yet far from perfect; but it is an important tool, and there must be a good deal of emphasis at this time on training in its use, particularly for those whose
means
medical education antedated its introduction. Even in current medical curricula, training in developmental assessment is probably inadequate. Within the context of medical practice it would be unfortunate if those who devote their lives to child development, particularly to developmental assessment, became unduly separated from the generality of doctors who look after children, if their methods, their language, and the unlimited multiplication of their techniques created a discipline of proportions so forbidding and aspect so esoteric that the ordinary doctor was afraid to involve himself in it. University Department of Child Life and Health, 17 Hatton Place,
Edinburgh
EH9 1UW.
J. O. FORFAR.
SIR,-Dr. Meadow asks (Dec. 25, p. 1430) what is to be done about the confusion of tests available for the assessment of development in children. We suggest that the basic tool needed is the Griffiths Mental Development Scale. This extends from the first few weeks to the end of the eighth year. It provides not only a general quotient of overall progress but also a detailed profile of mental age, locomotor development, personal/social development, speech, hearing, eye/hand coordination, and performance; and for the later years it provides a subscale called practical reasoning. The scale is based largely on observations of play and of the child’s self-imposed tasks. Testing requires much patience, and not all doctors have this aptitude; but