- Email: [email protected]
Occupational health service
59
THE LANCET, JANUARY 2, 1971
vision technology. With the wider availability of lower-cost equipment, I tmrm thxs is on the verge of becoming universal. Good television teaching tapes can be and are being produced. These are not difficult to edit if the proper electronic editing equipment is used. Our group has been engaged in the production of training tapes for distribution to hospitals within New York State, and, even at the comparatively restricted level of a pilot project, these tapes have been well received. We encourage feed-back from our viewers and attempt to improve our product accordingly. It seems to me that we should try to encourage the creative use of television in medical training, while at the same time discouraging haphazard acquisition of equipment by the technically unsophisticated. I commend to your readers the excellent study by Oettinger and Marks x f o r a lucid view of similar problems in parallel fields, Department of Educational Research, New York State Psychiatric Institute, New York, N.Y. 10032.
JOHN GRAVES VALERIE GRAVES.
RADIOLOGICAL ASSESSMENT OF THE LARYNX 8IR,--Dr. Rideout (Dec. 5, p. 1196) states that the results of tomographie examination of the larynx are excellent, and t h a t a positive-contrast laryngogram is seldom required. Could I, first of all, ask how he knows that the results of his examination are excellent, since all his patients were subsequently treated by radiotherapy, so that the larynx Was not removed and could not be examined accurately to delineate the turnout ? Clinical methods of examination of the larynx are relatively inaccurate, and the only absolutely accurate method of estimating "the size and extent of a eal turnout is to remove the larynx and examine it. -l-~ . - _g _ I.
University Department of Oto-rhino-laryngology, Ear, Nose and Throat Infirmary, Liverpool L7 7DF.
P . M . STELL.
PAUL W. MOSHER.
SIR,~As we are so m u c h involved in producing slide/ audiotapes for teaching, we have followed this correspondence with interest. We feel compelled to emphasise what is so often forgotten: these are aids, not substitutes, for teachers, whose time should not be wasted on routine teachinn that can be better presented as programmed selfinstructional material in whichever medium surfs the particular school. Teachers then have more time for that personal tutorial contact with students which we all agree is so desirable. T h e report of our recent conference (Third Conference on Audiotape in Medical Teaching, Oct. 14, 1970), at which these points were thoroughly discussed, is in the press. Mr. Stuart Meatchem (Dec. 19, p. 1315), and the clinical tutors he mentions, may like to know that teaching slides (as well as slides with tapes) are available on loan from our Foundation. We have a large collection, in constant demand, ~ d we have obtained a grant from the Nuffield Provincial Hospkals Trust to make the collection more comprehensive and to catalogue it. We are specially interested in general practice, social and community medicine, and common and minor illnesses, since these are rarely photographed b u t much needed for teaching, but we include slides on any medics! topic. Medical schools do indeed have many splendid 35 ram. slides, but not all of them are available for loan or catalogued for easy retrieval for teaching. We should be interested to hear from anyone engaged in collecting slides for loan. Medical Recording ServiceFoundation (Royal College of General' Practitioners), Kitts Croft, Writtle, ChelmsfordCM1 3EH,
Secondly, I note that Dr. Rideout uses tomographic cuts with an arc of 30 ° at half-centimetre intervals, despite the experimental work of Ardran and Emrys Roberts, ~ which has shown that it is impossible to delineate a laryngeal turnout accurately at such intervals with exposure angles of less than 60 °. Lastly, I think it should be noted that, although laryngograms are not advised in every patient with a turnout of the larynx, they are of value as part of the investigations of patients who are being considered for partial laryngeal surgery and for patients with stenosis of the larynx and upper trachea. Laryngograms have the advantage over tomograms that they provide a functional assessment of the larynx, allowing mobility of its various parts to be assessed.
v~-u,ger, A. G., Marks, S. Run, Computer, Run: The M ~ o l o ~ vi J~l ucational Innovation--an Essay Cambridge, Mass., 1969.
OCCUPATIONAL HEALTH SERVICE SIR,--In your editorial of Oct. 3 (p. 701) it was suggested that the Government should await the report of the Robens Committee on safety and health at work before reintroducing the legislation to establish an Employment Medical Advisory (E.M.A.) Service. I n a later issue (Nov. 7, p. 980) your views were criticised by Prof. Richard Schilling. Lest it be thought that Professor Schilling was speaking for the profession, may I hasten to add that, on the contrary, the B.M,A., the Society of Occupational Medicine, and the Royal College of Nursing all support your views. Many of us with first-hand knowledge of occupationa ! health problems viewed with alarm the original proposals " embodied in the Employed Persons (Health and Safety) Bill 1970, which just failed to reach the statute book before the general election. Prior consultation and agreement, "which the original White Paper assumed, in my view, did not exist, and, once the journey towards the statute book began, one felt completely unable to influence the course of events. Now that we have been given a breathing space, let us all try to be both constructive and realistic. For example, one of the proposals in the n e w service was that the employment medical advisers would assume responsibility with regard to rehabilitation in industrial rehabilitation units and the extent to which Government training centres are used for rehabilitation. They would also assume responsibility for assessment hitherto carried out by regional medical officers. I n the place of preemployment medical examinations of young persons c a r r i e d out previously by A.I~.D.s, a new selective referral of disabled school-leavers would take its place. All these constitute a very-formidable task. Moreover, tl~ese represent but one side of the coin of rehabilitation. As chairman of a subcommittee ,(of the Scottish Medical Advisory Committee) on rehabilitation under the N.H.S., I have been struck by the dynamic, and realistic approach to the subject in Europe compared with that in our own country. It was never quite clear where the 73 E.M.A. doctors would be recruited, and, once in pffst, how they would be trained in rehabilitation, other than by some brief orientation course. I n Norway, the training of a rehabilitation, as distinct from a physical-medicine, specialist takes five years, as foUows: i year in rheumatology; 1 year in'internal medicine, or work physiology, or social medicine, o~ physical medicine; and 3 years in a rehabilitation depart.ment.
With a population three-fifths that of Scotland, Norway has thirty recognised rehabilrfation specialists and thirty in physical' medicine; here in Scotland we have five or six. 1. Ardran, G. M., Emrys Roberts, M. S. R. Clin. Radiol. 1965, 16, 369.
40
rrm I.Pa~CET,I~VAae 2, 1~!
Moreover, if rehabilitation be a continuous process (artificially divided into medical and industrial components because of different ministerial responsibilities), then it seems common sense to wait on the reports on medical rehabilitation by the English and Scottish committees rather than try to plan for the future in a vacuum. University Department of Social and Occupational Medicine, Dundee. .Ar.l~ I~AIR.
TREATMENT OF AN2ESTHETIC-INDUGED MALIGNANT HYPERPYREXIA SIR,~With the demonstration of a deficiency in calcium sequestration by sarcoplasmic reticulum from muscle of patients who had recovered from an episode of malignant hyperpyrexia with rigidiw~ Professor Kalow and his colleagues (Oct. 31, p. 895) suggest a plausible underlying pathophysiology which may eventually lead to a logical treatment.' But meanwhile perhaps they should have given more emphasis to the remarkably successful treatment of one of their patients by infusion o f a large dose of procainamide. Presumably in this patient the local-anaesthetic agent was given to control ventricular arrhythmias, which are often a preterrninal event. But why was procainamide chosen rather tllan lidocaine (lignocaine), the more commonly used antiarrhythmic in anmsthetic practice ? Procainamide may indeed be better, in view of pharmacological peculiarities of lidocaine. Whereas the caffeine contracture in frog sartorius muscle may be blocked by many local-anmsthetic agents, ~ it is potentiated by lldocaine. 2 Caffeine-induced increased oxygen consumption of sartorius muscle is blocked by procaine but potentiated by lidocaine. 3 The effect of local-anaesthetic agents on accumulation of calcium by isolated sarcoplasmic reficulum parallels that expected from effects in whole muscle. ~ Thus, perhaps Professor Kalow and his colleagues are in a position to recommend administration of local-anmsthefic agents as logical treatment for anaesthetic hyperpyrexia accompanied by rigidity. Despite Katz's ~ apparent success with lidocaine infusion in treating the tachycardia of an early hypertherrnic reaction, perhaps procainamide rather than lidocaine should be the recommended drug, until we have evidence to the contrary. The definite recommendation o f large doses of localanmsthetic agent as a means of controlling an underlying abnormal response of sarcoplasmic reticulum to halothane should perhaps await confirmation in other systems~e.g., the hyperthermic response of Landrace pigs to halothane, s Department of Anesthesia, Hospital of the University of Pennsylvania,
Philadelphia, Pennsylvania 19104.
GEORGE E. STROBEL.
C/ESAREAN SECTION UNDER •L O C A L A N A L G E S I A SIRs~For many years now we at this hospital have carricd out csesarean section under local analgesia with consistently good results and remarkably few failures. It is true, as Dr. Rodriguez writes (Nov. 14, p. 1036), that localisation of the parietal peritoneum may cause difficulties I. 2. 3. 4. 5. 6.
Feinstein, M. B. J. gen. Physiol. 1963, 47, 151. Bianchi, S. P., BoRon, T. C..7. Pharraa¢. exp. Ther. 1967, 157, 388. Iqovomy,I., Bianchi, C. P. ibid. 1967j 155, 456. Johnson, P. N., Inesi, G. ibid. 1969, 169, 308. Katz, D. Anesth. Analg. 1970, 49, 225. Harrison, G. G., Saunders, S. J., Biebuyck, J. C., Hickman, R., Dent, D. ,M., Weaver, V., Terblanehe, j'. Br..7. An~ssth. 1969. 41, 844. '
which, very occasionally, force us to turn to gert~ an:esthesia. Our method is to infiltrate beneath the alba when this is exposed by a midline incision, using same 1% procaine with adrenaline as for the rest of operation. Premedication is impo~ant. We use 100 n~ pethidine with nallorphine, and 10-15 rag. of droperid~l (given slowly with frequent blood-pressure checks, s ~ hypotension can be dangerous) to induce dissociation ~. allay fear. Retractors and packs are not" used, and method demands gentleness on the part o f the surgcd~ together with that modesty of speech which has always~ be remembered during procedures under' local analgesii Charles Johnson Memorial Hospital, Nqutu,.Zululand. ANTIIO.WY BARKER.
K E T A M I N E IN N E U R O S U R G I C A L PROCEDURES SIR,--Ketamine (' Ketalar ') has been recommended an anmsthetic agent for neurodiagnostic procedures. agent consistently causes some hypertension. It is theref~ to be expected that there would be some r i s e i n intrath~ pressure. We have used ketamine (a single'intravenous ~ of 1"2-4.3 rag. per kg. and one intramuscular dose~ i0 rag. per kg.) as a general anesthetic agent to facilit~ lumbar puncture in a few neurosurgical patients. M e a s ~ ment of the mtrathecal pressures on such occasions lesit us to believe that this agent produces levels of intrathe~ and therefore intracranial, pressures which are undesirabk in certain circumstances. Case / . - - L u m b a r ptmctures were performed on a 16 year-old boy who had had a Torkildsen's ventricu~ cysternostomy for aqueduct stenpsis. The object was~ remove cerebrospinal fluid (C.S.F.) and thus reduce t~ intrathecal pressure to approximately normal levels (iti usual to record moderately high pressures for a postoper~ tive period of as much as 2-3 weeks in such cases). Duri~ the 3rd postoperative week lumbar punctures were lX~ tbrmed daily using either ketamine or droperidol (0.12 per kg.) with essentially similar puncture, manometry, am drainage techniques. The recorded pressures were follows: Days after operation
Kctamine
14 15
250 rnm. e.s.F. 300 turn. e.s.v.
16
17 18
250 ram. c.s.~.
Droperldol
145 ram. e.s.F.
140 ram. C.S.F.
Cases 2, 3, and 4 . - - T h r e e patients with no evidence# cerebral or cardiovascular disease, when investigated f& prolapsed lumbar intravertebral discs, had lumbar pune ruses (standardised procedure) for routine study of c,¢1~ and intrathecal injection of ' M y o d i l ' while an:esthetisd with ketamine. Intrathecal pressures were: case 250 man. C.S.F.; ease 3, 210 ram. G.S.F.; and case 4, 250 tr~ c.s.F, These pressures are greater than we recorded g. similar cases with local anaesthesia. I f kctamine consistently produces a rise in intrathcg# pressure its use, in our opinion, is contraindicated in t~ following neurosurgical and neuroradiological situations: 1. Procedures involving diagnostic c.s.l~, manometry. 2. Cases where there is to be cerebral angiography. In s~ cases a further rise in intracranial pressure might cauSt~t hold-up of contrast medium at the intracavernous-!~ arachnoid junction of the internal carotid artery and hr-~ result in films of poor diagnostic quality. 3. Patients with evidence of raised intracranial pressure 0¢ space-occupying lesion. A further rise in intracr~
THE LANCET, JANUARY 2, 1971
vision technology. With the wider availability of lower-cost equipment, I tmrm thxs is on the verge of becoming universal. Good television teaching tapes can be and are being produced. These are not difficult to edit if the proper electronic editing equipment is used. Our group has been engaged in the production of training tapes for distribution to hospitals within New York State, and, even at the comparatively restricted level of a pilot project, these tapes have been well received. We encourage feed-back from our viewers and attempt to improve our product accordingly. It seems to me that we should try to encourage the creative use of television in medical training, while at the same time discouraging haphazard acquisition of equipment by the technically unsophisticated. I commend to your readers the excellent study by Oettinger and Marks x f o r a lucid view of similar problems in parallel fields, Department of Educational Research, New York State Psychiatric Institute, New York, N.Y. 10032.
JOHN GRAVES VALERIE GRAVES.
RADIOLOGICAL ASSESSMENT OF THE LARYNX 8IR,--Dr. Rideout (Dec. 5, p. 1196) states that the results of tomographie examination of the larynx are excellent, and t h a t a positive-contrast laryngogram is seldom required. Could I, first of all, ask how he knows that the results of his examination are excellent, since all his patients were subsequently treated by radiotherapy, so that the larynx Was not removed and could not be examined accurately to delineate the turnout ? Clinical methods of examination of the larynx are relatively inaccurate, and the only absolutely accurate method of estimating "the size and extent of a eal turnout is to remove the larynx and examine it. -l-~ . - _g _ I.
University Department of Oto-rhino-laryngology, Ear, Nose and Throat Infirmary, Liverpool L7 7DF.
P . M . STELL.
PAUL W. MOSHER.
SIR,~As we are so m u c h involved in producing slide/ audiotapes for teaching, we have followed this correspondence with interest. We feel compelled to emphasise what is so often forgotten: these are aids, not substitutes, for teachers, whose time should not be wasted on routine teachinn that can be better presented as programmed selfinstructional material in whichever medium surfs the particular school. Teachers then have more time for that personal tutorial contact with students which we all agree is so desirable. T h e report of our recent conference (Third Conference on Audiotape in Medical Teaching, Oct. 14, 1970), at which these points were thoroughly discussed, is in the press. Mr. Stuart Meatchem (Dec. 19, p. 1315), and the clinical tutors he mentions, may like to know that teaching slides (as well as slides with tapes) are available on loan from our Foundation. We have a large collection, in constant demand, ~ d we have obtained a grant from the Nuffield Provincial Hospkals Trust to make the collection more comprehensive and to catalogue it. We are specially interested in general practice, social and community medicine, and common and minor illnesses, since these are rarely photographed b u t much needed for teaching, but we include slides on any medics! topic. Medical schools do indeed have many splendid 35 ram. slides, but not all of them are available for loan or catalogued for easy retrieval for teaching. We should be interested to hear from anyone engaged in collecting slides for loan. Medical Recording ServiceFoundation (Royal College of General' Practitioners), Kitts Croft, Writtle, ChelmsfordCM1 3EH,
Secondly, I note that Dr. Rideout uses tomographic cuts with an arc of 30 ° at half-centimetre intervals, despite the experimental work of Ardran and Emrys Roberts, ~ which has shown that it is impossible to delineate a laryngeal turnout accurately at such intervals with exposure angles of less than 60 °. Lastly, I think it should be noted that, although laryngograms are not advised in every patient with a turnout of the larynx, they are of value as part of the investigations of patients who are being considered for partial laryngeal surgery and for patients with stenosis of the larynx and upper trachea. Laryngograms have the advantage over tomograms that they provide a functional assessment of the larynx, allowing mobility of its various parts to be assessed.
v~-u,ger, A. G., Marks, S. Run, Computer, Run: The M ~ o l o ~ vi J~l ucational Innovation--an Essay Cambridge, Mass., 1969.
OCCUPATIONAL HEALTH SERVICE SIR,--In your editorial of Oct. 3 (p. 701) it was suggested that the Government should await the report of the Robens Committee on safety and health at work before reintroducing the legislation to establish an Employment Medical Advisory (E.M.A.) Service. I n a later issue (Nov. 7, p. 980) your views were criticised by Prof. Richard Schilling. Lest it be thought that Professor Schilling was speaking for the profession, may I hasten to add that, on the contrary, the B.M,A., the Society of Occupational Medicine, and the Royal College of Nursing all support your views. Many of us with first-hand knowledge of occupationa ! health problems viewed with alarm the original proposals " embodied in the Employed Persons (Health and Safety) Bill 1970, which just failed to reach the statute book before the general election. Prior consultation and agreement, "which the original White Paper assumed, in my view, did not exist, and, once the journey towards the statute book began, one felt completely unable to influence the course of events. Now that we have been given a breathing space, let us all try to be both constructive and realistic. For example, one of the proposals in the n e w service was that the employment medical advisers would assume responsibility with regard to rehabilitation in industrial rehabilitation units and the extent to which Government training centres are used for rehabilitation. They would also assume responsibility for assessment hitherto carried out by regional medical officers. I n the place of preemployment medical examinations of young persons c a r r i e d out previously by A.I~.D.s, a new selective referral of disabled school-leavers would take its place. All these constitute a very-formidable task. Moreover, tl~ese represent but one side of the coin of rehabilitation. As chairman of a subcommittee ,(of the Scottish Medical Advisory Committee) on rehabilitation under the N.H.S., I have been struck by the dynamic, and realistic approach to the subject in Europe compared with that in our own country. It was never quite clear where the 73 E.M.A. doctors would be recruited, and, once in pffst, how they would be trained in rehabilitation, other than by some brief orientation course. I n Norway, the training of a rehabilitation, as distinct from a physical-medicine, specialist takes five years, as foUows: i year in rheumatology; 1 year in'internal medicine, or work physiology, or social medicine, o~ physical medicine; and 3 years in a rehabilitation depart.ment.
With a population three-fifths that of Scotland, Norway has thirty recognised rehabilrfation specialists and thirty in physical' medicine; here in Scotland we have five or six. 1. Ardran, G. M., Emrys Roberts, M. S. R. Clin. Radiol. 1965, 16, 369.
40
rrm I.Pa~CET,I~VAae 2, 1~!
Moreover, if rehabilitation be a continuous process (artificially divided into medical and industrial components because of different ministerial responsibilities), then it seems common sense to wait on the reports on medical rehabilitation by the English and Scottish committees rather than try to plan for the future in a vacuum. University Department of Social and Occupational Medicine, Dundee. .Ar.l~ I~AIR.
TREATMENT OF AN2ESTHETIC-INDUGED MALIGNANT HYPERPYREXIA SIR,~With the demonstration of a deficiency in calcium sequestration by sarcoplasmic reticulum from muscle of patients who had recovered from an episode of malignant hyperpyrexia with rigidiw~ Professor Kalow and his colleagues (Oct. 31, p. 895) suggest a plausible underlying pathophysiology which may eventually lead to a logical treatment.' But meanwhile perhaps they should have given more emphasis to the remarkably successful treatment of one of their patients by infusion o f a large dose of procainamide. Presumably in this patient the local-anaesthetic agent was given to control ventricular arrhythmias, which are often a preterrninal event. But why was procainamide chosen rather tllan lidocaine (lignocaine), the more commonly used antiarrhythmic in anmsthetic practice ? Procainamide may indeed be better, in view of pharmacological peculiarities of lidocaine. Whereas the caffeine contracture in frog sartorius muscle may be blocked by many local-anmsthetic agents, ~ it is potentiated by lldocaine. 2 Caffeine-induced increased oxygen consumption of sartorius muscle is blocked by procaine but potentiated by lidocaine. 3 The effect of local-anaesthetic agents on accumulation of calcium by isolated sarcoplasmic reficulum parallels that expected from effects in whole muscle. ~ Thus, perhaps Professor Kalow and his colleagues are in a position to recommend administration of local-anmsthefic agents as logical treatment for anaesthetic hyperpyrexia accompanied by rigidity. Despite Katz's ~ apparent success with lidocaine infusion in treating the tachycardia of an early hypertherrnic reaction, perhaps procainamide rather than lidocaine should be the recommended drug, until we have evidence to the contrary. The definite recommendation o f large doses of localanmsthetic agent as a means of controlling an underlying abnormal response of sarcoplasmic reticulum to halothane should perhaps await confirmation in other systems~e.g., the hyperthermic response of Landrace pigs to halothane, s Department of Anesthesia, Hospital of the University of Pennsylvania,
Philadelphia, Pennsylvania 19104.
GEORGE E. STROBEL.
C/ESAREAN SECTION UNDER •L O C A L A N A L G E S I A SIRs~For many years now we at this hospital have carricd out csesarean section under local analgesia with consistently good results and remarkably few failures. It is true, as Dr. Rodriguez writes (Nov. 14, p. 1036), that localisation of the parietal peritoneum may cause difficulties I. 2. 3. 4. 5. 6.
Feinstein, M. B. J. gen. Physiol. 1963, 47, 151. Bianchi, S. P., BoRon, T. C..7. Pharraa¢. exp. Ther. 1967, 157, 388. Iqovomy,I., Bianchi, C. P. ibid. 1967j 155, 456. Johnson, P. N., Inesi, G. ibid. 1969, 169, 308. Katz, D. Anesth. Analg. 1970, 49, 225. Harrison, G. G., Saunders, S. J., Biebuyck, J. C., Hickman, R., Dent, D. ,M., Weaver, V., Terblanehe, j'. Br..7. An~ssth. 1969. 41, 844. '
which, very occasionally, force us to turn to gert~ an:esthesia. Our method is to infiltrate beneath the alba when this is exposed by a midline incision, using same 1% procaine with adrenaline as for the rest of operation. Premedication is impo~ant. We use 100 n~ pethidine with nallorphine, and 10-15 rag. of droperid~l (given slowly with frequent blood-pressure checks, s ~ hypotension can be dangerous) to induce dissociation ~. allay fear. Retractors and packs are not" used, and method demands gentleness on the part o f the surgcd~ together with that modesty of speech which has always~ be remembered during procedures under' local analgesii Charles Johnson Memorial Hospital, Nqutu,.Zululand. ANTIIO.WY BARKER.
K E T A M I N E IN N E U R O S U R G I C A L PROCEDURES SIR,--Ketamine (' Ketalar ') has been recommended an anmsthetic agent for neurodiagnostic procedures. agent consistently causes some hypertension. It is theref~ to be expected that there would be some r i s e i n intrath~ pressure. We have used ketamine (a single'intravenous ~ of 1"2-4.3 rag. per kg. and one intramuscular dose~ i0 rag. per kg.) as a general anesthetic agent to facilit~ lumbar puncture in a few neurosurgical patients. M e a s ~ ment of the mtrathecal pressures on such occasions lesit us to believe that this agent produces levels of intrathe~ and therefore intracranial, pressures which are undesirabk in certain circumstances. Case / . - - L u m b a r ptmctures were performed on a 16 year-old boy who had had a Torkildsen's ventricu~ cysternostomy for aqueduct stenpsis. The object was~ remove cerebrospinal fluid (C.S.F.) and thus reduce t~ intrathecal pressure to approximately normal levels (iti usual to record moderately high pressures for a postoper~ tive period of as much as 2-3 weeks in such cases). Duri~ the 3rd postoperative week lumbar punctures were lX~ tbrmed daily using either ketamine or droperidol (0.12 per kg.) with essentially similar puncture, manometry, am drainage techniques. The recorded pressures were follows: Days after operation
Kctamine
14 15
250 rnm. e.s.F. 300 turn. e.s.v.
16
17 18
250 ram. c.s.~.
Droperldol
145 ram. e.s.F.
140 ram. C.S.F.
Cases 2, 3, and 4 . - - T h r e e patients with no evidence# cerebral or cardiovascular disease, when investigated f& prolapsed lumbar intravertebral discs, had lumbar pune ruses (standardised procedure) for routine study of c,¢1~ and intrathecal injection of ' M y o d i l ' while an:esthetisd with ketamine. Intrathecal pressures were: case 250 man. C.S.F.; ease 3, 210 ram. G.S.F.; and case 4, 250 tr~ c.s.F, These pressures are greater than we recorded g. similar cases with local anaesthesia. I f kctamine consistently produces a rise in intrathcg# pressure its use, in our opinion, is contraindicated in t~ following neurosurgical and neuroradiological situations: 1. Procedures involving diagnostic c.s.l~, manometry. 2. Cases where there is to be cerebral angiography. In s~ cases a further rise in intracranial pressure might cauSt~t hold-up of contrast medium at the intracavernous-!~ arachnoid junction of the internal carotid artery and hr-~ result in films of poor diagnostic quality. 3. Patients with evidence of raised intracranial pressure 0¢ space-occupying lesion. A further rise in intracr~