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Dynamics of the Common Duct
236
In the viva and in the clinical it is usual for examiners in pairs according to the subject-two physicians, two surgeons, and two obstetricians. To a limited extent in recent years the pattern has been changed by pairing the physician with a paediatrician or psychiatrist, and the surgeon with an orthopaedic or ear, nose, and throat surgeon; but the candidate still faces a pair of highly specialised examiners with a medical or surgical bias. Would it be too bold an experiment to mix the disciplines and have the physician examine with a surgeon, the obstetrician with a physician, psychiatrist, or p2ediatrician ? This would at once put the examination on a
to act
broader
footing, remove the narrow specialised approach, and place the emphasis where it ought to be-on the essential wholeness of medicine. The deficiencies of the present final examination (as conducted in most schools) are not gross enough to justify scrapping it and starting afresh. But there is little point in experimenting with the content of basic medical education if there is not at the same time a willingness to ask with some insistence whether the final test of knowledge and skill is fair to the student and to those on whom he will practise. It is time that medical schools and licensing bodies said more of what they are doing to bring the qualifying examination up to date.
Dynamics
of the Common Duct
THE clinician trying to find an anatomical and physiological basis for the pain of biliary-tract disease may be forgiven if he returns empty-handed and exasperated from the literature and remains content with a phenomenological approach. Since 1761 when DUVERNEY first gave a clear description of the intimate anatomy of the gallbladder, many if not all of the writings on the subject have been bedevilled by problems of terminology, semantics, methods, and interpretation. Translating results from one species to another is also a difficulty, particularly since the structures are so variable in their gross anatomy and in their content of smooth muscle. Opportunities for direct study of the physiology of the extrahepatic biliary tree in man are very limited; when they do arise, the biliary passages may be abnormal because of calculous disease and its obstructive and
inflammatory complications. In 1898 HENDRICKSONwas the first to demonstrate scattered smooth muscle in the common duct of both 3 man and dog. Later, however, LUDWICK 2 and others suggested that most ducts in the dog do not have any muscle. The arrangement described is a discontinuous longitudinal inner coat and sparse circular fibres in the outer layers, the amount of muscle increasing towards the lower end where it becomes continuous with the part of the duodenal musculature that forms the " sphincter choledochus ". This distribution of muscle in the duct 1. 2. 3.
Hendrickson, W. F. Bull. Johns Hopkins Hosp. 1898, 9, 221. Ludwick, J. R. Ann. Surg. 1966, 164, 1041. Mahour, G., Wakim, K. G., Soule, E. H., Ferris, D. O. ibid. 1967, 166, 91.
would
permit limited shortening and lengthening moveperistalsis. Consequently, the movements of the duct described by BURNETT and SHIELDS4 on cinefluoroscopy probably represent coordinated activity of the duodenal wall and sphincter; that this can be associated with changes in duct size has lately been confirmed.5 WATTS and DUNPHY s showed that rhythmic pressure changes are detectable in segments of the dog’s
ments
but not
bileduct in vivo, both in the unstimulated state and after administration of mecholyl, cholecystokinin, or morphine, or after electrical stimulation of the distal cut end of the vagus nerves. Rhythmic contraction of longitudinally cut strips of the canine common bileduct were also demonstrated in vitro. LUDWICK and BASS,7 however, who applied force transducers to the dog’s common bileduct, failed to find any motility with the pharmacological stimuli used by WATTS and DUNPHY, although activity was detected in the monkey. Even harder to unravel are the mechanics of the complex musculature in the sphincteric region at the lower end of the common duct. The conventional view is that the sphincter of Oddi responds to cholecystokinin, released from the duodenal mucosa, by relaxation, thus allowing free passage of gallbladder and hepatic bile into the duodenum after a meal. WATTS and DUNPHY postulate a more active role for this sphincter; for, in the dog, direct pressure recordings in the sphincter region demonstrated increased activity after cholecystokinin administration at the same time as a fall in resistance to the infusion of saline solution through the lower end of the common duct into the duodenum. The muscle in the duodenal wall and sphincter of Oddi stimulated by cholecystokinin could therefore actively milk bile from the common bileduct into the duodenum. For obvious reasons these experiments have not been repeated in 8 man, but the cinefluoroscopic studies of CAROLi et awl. on the movements of this sphincteric complex are certainly in keeping with this idea of active pumping of bile from the common duct into the duodenum. Can any link be seen between these anatomical and physiological observations and clinical events ? The elegant analysis of FRENCH and RoBB 9 of the nature of biliary pain suggested tension rather than rhythmic muscle contraction as the chief cause in patients whose gallbladder was still present. Few comparable analyses have been made in patients with calculi in the common bileduct after removal of the gallbladder, but DORAN 10 has lately made a careful study of patients whose common duct was stimulated by the distension of a small balloon attached to the indwelling drainage tube. Pain was widely distributed in the epigastrium, in the right hypochondrium, and in the back, and resembled that of distension. At least some of the variability may, as DORAN postulates, represent differences in the central terminations of the nerve pathways to the duct. The absence of common
Burnett, W., Shields, R. Lancet, 1958, ii, 387. Nebaser, R. A., Pollard, J. J., Potsaid, M. S. Radiology, 1966, 86, 475. Watts, J. McK., Dunphy, J. E. Surgery Gynec. Obstet. 1966, 122, 1207. Ludwick, J. R., Bass, P. ibid. 1967, 124, 536. Caroli, J., Porcher, P., Pequignot, G., Delattre, M. Am. J. dig. Dis. 1960, 5, 677. 9. French, E. B., Robb, W. A. T. Br. med. J. 1963, ii, 135. 10. Doran, F. S. A. Br. J. Surg. 1967, 54, 599. 4. 5. 6. 7. 8.
237
harder to explain: it may mean that the duct is without innervation because of distance from the neural crest, although this condition has not been recorded in histological studies 11: more probably it is a consequence of disease in the duct wall. The relation between the pain and the muscular activity is equally obscure; in view of the apparent ability of the common duct to generate tension, it is feasible that common-duct distension invokes muscular activity and an increase in tone of the lower sphincter complex, but no-one has yet proved that stretch receptors exist in the common duct. The subject is clearly a fertile one for both controversy and experiment by clinician and
pain in
11 out of 47
patients is
physiologist. Annotations A GREATER MEDICAL SCHOOL?
SINCE 1962 a train of working-parties, convened by Dr. Nicholas Malleson, has been examining some of the curricular and administrative decisions which the new medical schools in Britain must face. The fifth party, with Sir Ronald Tunbridge as chairman, has now set out 12 its proposals-the most auspicious of the series perhaps-for a comprehensive medical school. Its aims have been to consider how far new patterns of medical education could encompass the education and training of health-service personnel other than doctors; how we might improve the education of scientists in fields related to medicine and the training of laboratory workers, nurses, social workers, hospital and health-service administrators, and counsellors of different types; and what new kinds of professional and " paraprofessional " (a word to be avoided perhaps) workers might in future be needed in the Health Service, particularly in general practice and community care, and how to train them. The working-party boldly recommends the experimental institution in one or more areas of " a comprehensive medical school in which a designated polytechnic joins in close working relationship with a clinical medical school, a university school of human biology and the other appropriate departments of the university." This organisation, the plan goes, should meet the training needs of the entire range of work in the National Health Service and related areas. Formidable: deans may tremble and matrons blench; but let no-one condemn the idea just because it racks certain nerves. The working-party believes that cooperation between all branches of the " greater medical profession " would be promoted and enhanced if both the initial and continuing education of all the professions related to medicine were organised with more of a common framework than is usual today. Without waiting for the amens to that, the report tackles instantly what is likely to be the most contentious area-nursing education, which " along with the education of doctors, must constitute the main feature of a comprehensive medical school." Proposals for experiment in nursing education must accept great scatter of ability and educational attainment on intake. " Any new 11. Burnett, W., Cairns, F. W., Bacsich, P. Ann. Surg. 1964, 159, 8. 12. A Comprehensive Medical School. Report of Working Party V, School of Medicine and Human Biology Committee. Published by the Institute for Social Research, 11 Nelson Road, London S.E.10.
8s. 6d.
system should therefore aim at the provision of a very wide and flexible series of courses making it possible for people of different abilities to hive off from professional education into practical work within their competence and ambition at different stages throughout their training." The report foresees no great changes in most of the established schools of nursing, whether large schools attached to the London teaching hospitals or the very small schools attached to district hospitals. " But there is a strong case for a major reconsideration of the intermediate schools particularly where a new or greatly expanded medical school is to be formed or where nursing schools in the large provincial cities are currently having difficulties with their recruitment and training. We have come to the view that these nursing schools should be organised not as part of the Hospital Service, but should be within a division of the polytechnic and answerable through the local education authorities to the Department of Education and Science for its finance." Teachers in the nursing schools within the hospital service in the area of the comprehensive medical school would be remustered as part of the local education authorities’ teaching staff-for the most part, little more than a speeding up of a trend already strong in many areas. The working-party does not, at this stage, propose any nursing curricula; but it advocates the principle of sandwich courses, alternating periods of study and practical experience, with tutors in both fields working closely together. This association of a university school of human biology with a polytechnic, and the cooperation of the nursing services of the hospital and of the community, will, it is envisaged, make possible a series of nursing courses ranging from those based on an academic degree through to a vocational State-enrolled nurse
qualification.
The polytechnic’s proposed " division of health sciences " would be responsible for the education of nurses; and the special schools, such as physiotherapy and radiography, and the training of supervisory personnel for the whole range of health-service work would also be developed within the polytechnic. The university’s main share of the combine would be the school of human biology, the clinical medical school, and the departments of pharmacy and pharmacology and of sociology and social administration. The three-year B.sc. course in human biology would offer a broad range of options for the third year; and here the report mentions particularly the increasing need for skills in bioengineering, medical electronics, medical physics, and the application of computer science to medicine and medical administration. The working-party also outlines how the training of ancillary staff for group practices and health centres might be accomplished; and the emphasis here is on community health. A place would also be found in the new structure for the training needs of voluntary workers, at present met through a great variety of agencies and voluntary societies.
COMPUTER STUDY OF DRUGS
with existing methods of assessing drugs by experience or by circumscribed clinical trials; findings come too slowly and are not always reliable. In a move to obtain faster and fuller information Dr. Hershel Jick and his colleagues at the Lemuel Shattuck Hospital in Boston, Massachusetts, inaugurated in 1966 a scheme for surveillance of drug No-oNE
can
be
content
clinical
In the viva and in the clinical it is usual for examiners in pairs according to the subject-two physicians, two surgeons, and two obstetricians. To a limited extent in recent years the pattern has been changed by pairing the physician with a paediatrician or psychiatrist, and the surgeon with an orthopaedic or ear, nose, and throat surgeon; but the candidate still faces a pair of highly specialised examiners with a medical or surgical bias. Would it be too bold an experiment to mix the disciplines and have the physician examine with a surgeon, the obstetrician with a physician, psychiatrist, or p2ediatrician ? This would at once put the examination on a
to act
broader
footing, remove the narrow specialised approach, and place the emphasis where it ought to be-on the essential wholeness of medicine. The deficiencies of the present final examination (as conducted in most schools) are not gross enough to justify scrapping it and starting afresh. But there is little point in experimenting with the content of basic medical education if there is not at the same time a willingness to ask with some insistence whether the final test of knowledge and skill is fair to the student and to those on whom he will practise. It is time that medical schools and licensing bodies said more of what they are doing to bring the qualifying examination up to date.
Dynamics
of the Common Duct
THE clinician trying to find an anatomical and physiological basis for the pain of biliary-tract disease may be forgiven if he returns empty-handed and exasperated from the literature and remains content with a phenomenological approach. Since 1761 when DUVERNEY first gave a clear description of the intimate anatomy of the gallbladder, many if not all of the writings on the subject have been bedevilled by problems of terminology, semantics, methods, and interpretation. Translating results from one species to another is also a difficulty, particularly since the structures are so variable in their gross anatomy and in their content of smooth muscle. Opportunities for direct study of the physiology of the extrahepatic biliary tree in man are very limited; when they do arise, the biliary passages may be abnormal because of calculous disease and its obstructive and
inflammatory complications. In 1898 HENDRICKSONwas the first to demonstrate scattered smooth muscle in the common duct of both 3 man and dog. Later, however, LUDWICK 2 and others suggested that most ducts in the dog do not have any muscle. The arrangement described is a discontinuous longitudinal inner coat and sparse circular fibres in the outer layers, the amount of muscle increasing towards the lower end where it becomes continuous with the part of the duodenal musculature that forms the " sphincter choledochus ". This distribution of muscle in the duct 1. 2. 3.
Hendrickson, W. F. Bull. Johns Hopkins Hosp. 1898, 9, 221. Ludwick, J. R. Ann. Surg. 1966, 164, 1041. Mahour, G., Wakim, K. G., Soule, E. H., Ferris, D. O. ibid. 1967, 166, 91.
would
permit limited shortening and lengthening moveperistalsis. Consequently, the movements of the duct described by BURNETT and SHIELDS4 on cinefluoroscopy probably represent coordinated activity of the duodenal wall and sphincter; that this can be associated with changes in duct size has lately been confirmed.5 WATTS and DUNPHY s showed that rhythmic pressure changes are detectable in segments of the dog’s
ments
but not
bileduct in vivo, both in the unstimulated state and after administration of mecholyl, cholecystokinin, or morphine, or after electrical stimulation of the distal cut end of the vagus nerves. Rhythmic contraction of longitudinally cut strips of the canine common bileduct were also demonstrated in vitro. LUDWICK and BASS,7 however, who applied force transducers to the dog’s common bileduct, failed to find any motility with the pharmacological stimuli used by WATTS and DUNPHY, although activity was detected in the monkey. Even harder to unravel are the mechanics of the complex musculature in the sphincteric region at the lower end of the common duct. The conventional view is that the sphincter of Oddi responds to cholecystokinin, released from the duodenal mucosa, by relaxation, thus allowing free passage of gallbladder and hepatic bile into the duodenum after a meal. WATTS and DUNPHY postulate a more active role for this sphincter; for, in the dog, direct pressure recordings in the sphincter region demonstrated increased activity after cholecystokinin administration at the same time as a fall in resistance to the infusion of saline solution through the lower end of the common duct into the duodenum. The muscle in the duodenal wall and sphincter of Oddi stimulated by cholecystokinin could therefore actively milk bile from the common bileduct into the duodenum. For obvious reasons these experiments have not been repeated in 8 man, but the cinefluoroscopic studies of CAROLi et awl. on the movements of this sphincteric complex are certainly in keeping with this idea of active pumping of bile from the common duct into the duodenum. Can any link be seen between these anatomical and physiological observations and clinical events ? The elegant analysis of FRENCH and RoBB 9 of the nature of biliary pain suggested tension rather than rhythmic muscle contraction as the chief cause in patients whose gallbladder was still present. Few comparable analyses have been made in patients with calculi in the common bileduct after removal of the gallbladder, but DORAN 10 has lately made a careful study of patients whose common duct was stimulated by the distension of a small balloon attached to the indwelling drainage tube. Pain was widely distributed in the epigastrium, in the right hypochondrium, and in the back, and resembled that of distension. At least some of the variability may, as DORAN postulates, represent differences in the central terminations of the nerve pathways to the duct. The absence of common
Burnett, W., Shields, R. Lancet, 1958, ii, 387. Nebaser, R. A., Pollard, J. J., Potsaid, M. S. Radiology, 1966, 86, 475. Watts, J. McK., Dunphy, J. E. Surgery Gynec. Obstet. 1966, 122, 1207. Ludwick, J. R., Bass, P. ibid. 1967, 124, 536. Caroli, J., Porcher, P., Pequignot, G., Delattre, M. Am. J. dig. Dis. 1960, 5, 677. 9. French, E. B., Robb, W. A. T. Br. med. J. 1963, ii, 135. 10. Doran, F. S. A. Br. J. Surg. 1967, 54, 599. 4. 5. 6. 7. 8.
237
harder to explain: it may mean that the duct is without innervation because of distance from the neural crest, although this condition has not been recorded in histological studies 11: more probably it is a consequence of disease in the duct wall. The relation between the pain and the muscular activity is equally obscure; in view of the apparent ability of the common duct to generate tension, it is feasible that common-duct distension invokes muscular activity and an increase in tone of the lower sphincter complex, but no-one has yet proved that stretch receptors exist in the common duct. The subject is clearly a fertile one for both controversy and experiment by clinician and
pain in
11 out of 47
patients is
physiologist. Annotations A GREATER MEDICAL SCHOOL?
SINCE 1962 a train of working-parties, convened by Dr. Nicholas Malleson, has been examining some of the curricular and administrative decisions which the new medical schools in Britain must face. The fifth party, with Sir Ronald Tunbridge as chairman, has now set out 12 its proposals-the most auspicious of the series perhaps-for a comprehensive medical school. Its aims have been to consider how far new patterns of medical education could encompass the education and training of health-service personnel other than doctors; how we might improve the education of scientists in fields related to medicine and the training of laboratory workers, nurses, social workers, hospital and health-service administrators, and counsellors of different types; and what new kinds of professional and " paraprofessional " (a word to be avoided perhaps) workers might in future be needed in the Health Service, particularly in general practice and community care, and how to train them. The working-party boldly recommends the experimental institution in one or more areas of " a comprehensive medical school in which a designated polytechnic joins in close working relationship with a clinical medical school, a university school of human biology and the other appropriate departments of the university." This organisation, the plan goes, should meet the training needs of the entire range of work in the National Health Service and related areas. Formidable: deans may tremble and matrons blench; but let no-one condemn the idea just because it racks certain nerves. The working-party believes that cooperation between all branches of the " greater medical profession " would be promoted and enhanced if both the initial and continuing education of all the professions related to medicine were organised with more of a common framework than is usual today. Without waiting for the amens to that, the report tackles instantly what is likely to be the most contentious area-nursing education, which " along with the education of doctors, must constitute the main feature of a comprehensive medical school." Proposals for experiment in nursing education must accept great scatter of ability and educational attainment on intake. " Any new 11. Burnett, W., Cairns, F. W., Bacsich, P. Ann. Surg. 1964, 159, 8. 12. A Comprehensive Medical School. Report of Working Party V, School of Medicine and Human Biology Committee. Published by the Institute for Social Research, 11 Nelson Road, London S.E.10.
8s. 6d.
system should therefore aim at the provision of a very wide and flexible series of courses making it possible for people of different abilities to hive off from professional education into practical work within their competence and ambition at different stages throughout their training." The report foresees no great changes in most of the established schools of nursing, whether large schools attached to the London teaching hospitals or the very small schools attached to district hospitals. " But there is a strong case for a major reconsideration of the intermediate schools particularly where a new or greatly expanded medical school is to be formed or where nursing schools in the large provincial cities are currently having difficulties with their recruitment and training. We have come to the view that these nursing schools should be organised not as part of the Hospital Service, but should be within a division of the polytechnic and answerable through the local education authorities to the Department of Education and Science for its finance." Teachers in the nursing schools within the hospital service in the area of the comprehensive medical school would be remustered as part of the local education authorities’ teaching staff-for the most part, little more than a speeding up of a trend already strong in many areas. The working-party does not, at this stage, propose any nursing curricula; but it advocates the principle of sandwich courses, alternating periods of study and practical experience, with tutors in both fields working closely together. This association of a university school of human biology with a polytechnic, and the cooperation of the nursing services of the hospital and of the community, will, it is envisaged, make possible a series of nursing courses ranging from those based on an academic degree through to a vocational State-enrolled nurse
qualification.
The polytechnic’s proposed " division of health sciences " would be responsible for the education of nurses; and the special schools, such as physiotherapy and radiography, and the training of supervisory personnel for the whole range of health-service work would also be developed within the polytechnic. The university’s main share of the combine would be the school of human biology, the clinical medical school, and the departments of pharmacy and pharmacology and of sociology and social administration. The three-year B.sc. course in human biology would offer a broad range of options for the third year; and here the report mentions particularly the increasing need for skills in bioengineering, medical electronics, medical physics, and the application of computer science to medicine and medical administration. The working-party also outlines how the training of ancillary staff for group practices and health centres might be accomplished; and the emphasis here is on community health. A place would also be found in the new structure for the training needs of voluntary workers, at present met through a great variety of agencies and voluntary societies.
COMPUTER STUDY OF DRUGS
with existing methods of assessing drugs by experience or by circumscribed clinical trials; findings come too slowly and are not always reliable. In a move to obtain faster and fuller information Dr. Hershel Jick and his colleagues at the Lemuel Shattuck Hospital in Boston, Massachusetts, inaugurated in 1966 a scheme for surveillance of drug No-oNE
can
be
content
clinical