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NEW SHORT-ACTING THIOBARBITURATE
797 with two floss-silk ligatures. The radiographic finding of disease limited largely to the upper lobe was confirmed by palpation ; dissection of the hilum was extremely difficult owing to the presence of many glands adhering to the pulmonary artery and its main branches ; and in freeing one of these glands the main pulmonary artery was damaged and could not be repaired. It was consequently necessary to proceed to pneumonectomy, instead of to lobectomy as intended. On completion of the pneumonectomy the patient’s
ligated
condition remained satisfactory, and so the upper four ribs were removed to minimise the likelihood of subsequent mediastinal displacement.
general
Progress.-The postoperative course was singularly uneventful ; within a few days the patient’s general condition had
greatly improved and all signs of toxsemia had disappeared ; the blood-pressure became established at 120/60 mm. Hg, and the continuous murmur was replaced by a short low-pitched mid-systolic pulmonary bruit. The radiographic appearance fifteen days after operation is shown in fig. 2. At the time of publication, the patient remains in excellent health, has no cough or sputum, and does not complain of dyspnoea on ordinary exertion. She is up all day and will be discharged home in the next few weeks. Summary
Fig. 2-Radiograph
of chest fifteen
she developed a productive She was first lost weight. 1954.
days after operation.
cough, seen
felt very unwell, and one of us in May,
by
On examination her general condition was poor. There continuous murmur, together with a systolic thrill, in the second left intercostal space ; the blood-pressure was lOOi30 mm. Hg. There was no finger-clubbing. Radiography showed considerable spread of the tuberculous disease in the left upper lobe, where there was a large homogeneous oval opacity-evidently a blocked cavity-and there were scattered, though limited, fresh opacities in the right upper zone. The heart was not greatly enlarged, but screening in the left anterior oblique position revealed some prominence of the left ventricle. The sputum was positive for tubercle bacilli for the first time. On admission to High Carley Hospital on Aug. 2 her general condition had greatly deteriorated ; she was feverish and extremely ill, and radiographic examination (fig. 1) showed that the contents of the lesion in the left upper zone had been evacuated, leaving a large thick-walled cavity ; there was extensive bronchogenic spread of disease to the left lower
A woman, aged 35, with extensive pulmonary tuberculosis and patent ductus arteriosus, previously complicated by infective endarteritis, was successfully treated by combined ligation of the ductus, pneumonectomy, and
thoracoplasty
at
a
was a
zone,
mainly
to the
lingula.
REFERENCES
Conklin, W. S., Tuhy, J. E., Grismer, J. T. (1951) J. thorac. Surg. 22, 271. Crafoord, C. (1948) Brit. Heart J. 10, 71. Gross, R. E. (1947) J. thorac. Surg. 16, 314. Hubbard, J. P. (1939) J. Amer. med. Ass. 112, 729. Tuffier, M. (1891) Bull. Soc. anat., Paris, 66, 300. Wood, P. (1950) Diseases of the Heart and Circulation. London ; —
p. 228.
NEW SHORT-ACTING THIOBARBITURATE M.B. ANÆSTHETIC
PETER NOBES Lond., F.F.A. R.C.S., D.A.
REGISTRAR,
CHASE
ENFIELD GROUP OF
t
Treatment with postural rest and chemotherapy (streptomycin 1 g. daily and isoniazid 250 mg. daily) was begun, and after two months there was very striking improvement in her general condition. Radiography showed blocking of the large cavity in the left upper lobe, some slight contraction of the massive spread in the left lower zone, and almost complete disappearance of the small lesions in the right lung. Bronchoscopy revealed no sign of significant endobronchitis ; bloodcultures were repeatedly negative. At this stage-no doubt because of her considerable symptomatic improvement and numerous domestic anxietiesthe patient became very restless and it seemed unlikely that she would accept long-continued hospital treatment. We had therefore to consider immediate definitive treatment, for her condition was clearly still precarious. The risk of circulatory failure following pneumonectomy in the presence of a patent ductus with increased pulse-pressure was unquestionably grave. We therefore decided to do a thoracotomy, to ligate the ductus, and (if the patient’s condition was still satisfactory) to proceed there and then to resect the diseased lung-tissue. We calculated that the risk of bronchogenic dissemination of disease following thoracotomy would be considerable unless the tuberculous lesions could be dealt with at the same time. Operation (Nov. 1).-The dissection of the ductus was complicated by the presence of many adherent glands ; the vessel, the wall of which was not unduly thickened, was
single operation.
Our thanks are due to Dr. C. P. Brown, whose skill in anaesthesia made this operation possible, and to Dr. A. P. B. Waind, for information about the patient when she was under his care in 1952 for the treatment of infective endarteritis.
FARM
HOSPITAL
AND
THE
HOSPITALS, MIDDLESEX
IN anaesthesia for outpatients both hexobarbitone and sodium thiopentone have the great disadvantage that somnolence may persist after the operation. Weese and Koss (1954) and Dietman (1954) have described experimental and clinical experience with ’Baytenal,’ a new very short-acting anaesthetic, which is apparently eliminated from the body so rapidly that its administration is followed by little, if any, postoperative somnolence. This drug is sodium 5,5-allyl-(2-methyl-propyl)-thiobarbiturate. It is issued as a powder, which is readily soluble in water and is administered as a 10% solution, which, according to the manufacturers, is stable for thirty-six hours. It is not at present on sale in this
country. Weese and Koss (1954) based their observations 350
on
cases.
Their series included inpatients many of whom were ill and debilitated ; these were given premedication, but morphine and its derivatives were avoided. Outpatients were given no premedication and all types of surgical operation lasting up to 10 minutes were undertaken. In the average adult they injected 2-3 ml. of the 10% solution quite rapidly, and after about 11/2 minutes a further quantity, depending
798 TABLE I-FINDINGS WITH BAYTENAL IN FIVE INPATIENTS
the depth of narcosis or duration of operation. In no case did the total dose exceed 1 g. Where muscular relaxation was needed succinylcholine was administered. on
Weese and Koss emphasise that, because the freedom from subsequent excitement, the slight respiratory depression, and, above all, the very rapid elimination of this drug, the patients needed no supervision after operation ; there was no vomiting or other complication. Outpatients were able to leave the operating-theatre within a few minutes of the end of the operation, and to go home in 20-30 minutes. Clinical Trial
A clinical trial of baytenal has been undertaken at Chase Farm Hospital. Because little of the drug was available the series included only eleven patients. Their ages ranged from 17 to 62 ; and, in order to obtain an unobscured picture of the effects of the baytenal, cases were selected to exclude so far as possible those where the addition of long-acting relaxants, inhalational agents, or other intravenous drugs would be necessary. The inpatients, with one exception, received premedication with ’Omnopon ’ gr. 1/3 and seopolamine gr. 1/no’ The outpatients received no premedieation, with the exception of one who was given atropine gr. 1/100’ Baytenal was given mostly in a single dose, injected as rapidly as possible. The dose was estimated on the basis of the patient’s age, weight, and general condition and the probable duration of the operation. During anaesthesia some patients breathed air, while others received a nitrous-oxide/oxygen mixture at the rate of 5 and 2 litres per minute respectively either immediately following the injection or after several minutes where return of consciousness seemed likely before the end of the operation. Particular attention was directed to the duration of unconsciousness, judged by the time taken by the patients to register complete awareness of surroundings in response to questioning. The degree of respiratory depression, the time which elapsed before the patients were able to sit or walk unaided, and the presence or absence of excitement, amnesia, and nausea or vomiting were noted. The results are summarised in tables i and 11.
The blood-pressure was recorded and spirometry tracings taken by two observers. No premedication was given; the spirometer facepiece was applied, and time given to become accustomed to the apparatus. Baytenal 0-6 g. was given slowly over a period of 1 minutes. Rapid loss of consciousness occurred, preceded by a brief sensation of drowsiness; no taste was experienced. The blood-pressure fell from 138/90 to 120/80 mm. Hg and the pulse-rate rose from 72 per minute to 120 per minute. Very slight depression of respiratory amplitude was registered on the spirometer, but respiratory rate was unchanged. After a further P/2 minutes baytenal 0-4 g. was injected as quickly as possible. This injection was followed by a slight fall in both rate and volume of respiration, which returned to normal within 2 minutes. 2 minutes after this second injection a painful stimulus (digital pressure over the brachial plexus) caused increased depth and rate of respiration. 6 minutes after the initial injection the subject regained consciousness. He had no mental confusion whatever and was able to answer questions regarding time and place; there was no retrograde amnesia. After a further 6 minutes he was able to walk in a straight line, and within 22 minutes from the first injection was able to write an account of subjective sensations. The return to full consciousness was rapid, Slight euphoria persisted for about 2 hours ; but this in no way impaired the sense of wakefulness, nor the ability to drive a car and carry on with normal work within that period, This contrasted strongly with the 3-4 hours of pronounced somnolence experienced by the subject after 0-2 g. of sodium thiopentone a week previously. were
Discussion
The most striking feature in this series was the very short time in which patients regained normal conscious. ness with freedom from postansesthetic confusion or drowsiness. Equally important was the very short interval between recovery of consciousness and return of ability to sit, stand, and walk unaided. During anaesthesia respiratory depression was very slight, and in no case (except where succinylcholine was used) did apncea of more than a few seconds’ duration appear. Retching occurred in only three cases, and lasted for about 3 /.-1minute ; two of these three patients had received omnopon gr. 1/3 and scopolamine gr. 1/lso as premedication. In five cases a normal meal was taken within 2 hours after the anesthetic. It would seem that, if the " single-dose technique is used, at least 0-5 g. should be given to an adult patient. Baytenal may prove of special value for casualty or outpatient cases where it is particularly desired to avoid "
Experimental The
drug (P. N.).
was
administered
Observation
experimentally
to
a
volunteer
TABLE II-FINDINGS WITH BAYTENAL IN
SIX OUTPATIENTS
799 the
unpleasantness
of induction with
an
inhalation
anaesthetic, but where it is also important that the a very short time. Because of its rapid elimination it may be worth trying its administration by continuous drip infusion for longer operations. The contra-indications to sodium thiopentone should be applied equally to baytenal, though this drug causes less severe respiratory depression and may thus be more suitable for " poor risk " cases.
patient is ambulant within
Summary A new short-acting thiobarbiturate,Baytenal’ has been tested in eleven patients and in a healthy volunteer. This drug depresses respiration very slightly. It may prove particularly useful for anaesthesia in outpatients because of the rapid return of consciousness and the absence of postaneesthetic somnolence and confusion.
My thanks are due to Dr. P. W. S. Gray and Dr. D. Zuck, consultant anaesthetists to Chase Farm Hospital, for their help and encouragdment in the preparation of this paper. I am also grateful to Messrs. Bayer, of Leverkusen, Germany, for a
supply
of
Baytenal. REFERENCES
Dietman, K. (1954) Chirurg. 25, 185. Weese, H., Koss, F. H. (1954) Dtsch. med. Wschr. 79, 601.
Medical Societies ROYAL SOCIETY OF MEDICINE Induced
Hypothermia
further fall in the central temperature from this cause might lead to ventricular fibrillation and death. Dr. Scurr described how he induced hypothermia in small children under light anaesthesia and oxygen, perhaps with a muscle relaxant to prevent shivering. He used a cooling blanket through which circulated water at 2-4°C. Dr. T. C. GRAY (Liverpool) described the results of induced hypothermia in 110 patients, almost all adults. He advocated surface-cooling and demonstrated the technique with a colour film. Hypothermia was induced during light anaesthesia, with a muscle relaxant, and under the vasodilator effect of chlorpromazine. There was no shivering, and an adequate temperature fall could be obtained in one and a half hours. The tendency " towards an after-drop in temperature when active cooling ceased could be prevented by tilting the patient at fifteen-minute intervals, to prevent local accumulation of blood. Dr. Gray showed that this " after-drop " was most common in patients with a large surface-area whose temperature fell slowly during cooling. He thought that this technique was altogether more satisfactory than intravenous administration of a mixture of chlorpromazine, promethazine hydrochloride, and pethidine followed by surface-cooling, which was slow in effect and often complicated by shivering. He and his colleagues had used induced hypothermia for intrathoracic, neurosurgical, and general surgical operations. Hypothermia had also been produced therapeutically, but without conspicuous success. In neurosurgery its particular value seemed to be the increased safety with which induced hypotension could be used for long periods with the patient in the upright position, while in general surgery a low temperature seemed to offer some protection against the effects of surgical trauma ; this was most obvious in poor-risk patients. In the whole series of 110 cases there were 13 deaths. These were very poor-risk patients ; but 3 of the deaths among patients submitted to neurosurgical operations were from pulmonary embolus, and Dr. Gray thought there might be some significance in this. Attempts to measure the pituitary-adrenal responses of patients to surgical stress with and without induced hypothermia had not yet shown much difference, but from experimental work on dogs Dr. Gray thought there was evidence that these responses were modified to the ultimate benefit of the animal. In the discussion that followed, Dr. J. W. DUNDEE (Liverpool) remarked on the particular value of induced hypothermia for neurosurgical cases. In one case he described the surgeon had clamped the middle cerebral artery for seven and a half minutes without postoperative
THE anaesthetics section met on April 1, under the of Dr. BERNARD JOHNSON, president of the to discuss Induced Hypothermia. section, Dr. C. F. ScuRR observed that tissue anoxia due to circulatory arrest, unless rapidly relieved, led to cellular death ; but if the body-temperature was lowered cellular metabolism and oxygen demands were reduced, so the cells survived the anoxia for longer periods. A hypothermic technique might be valuable for intracardiac operations, for transposition of the great vessels, for operations for congenital cyanotic heart-disease, for certain intracranial operations, and for some abdominal and thoracic operations such as excision of an aortic aneurysm. There were five advantages to be gained. First, the oxygen requirements of the tissues were reduced, since if shivering was prevented oxygen consumption fell in a linear fashion with fall of body-temperature. Secondly, cardiac work was reduced. Thirdly, the coagulation-time of the blood was increased, which might be beneficial in certain types of cardiovascular surgery where thrombosis was a potential danger. Fourthly, anaesthetic requirements were reduced. Fifthly, harmful bacterial and enzyme activity was Dr. Scurr noted several disadvantages which necessitated special care on the part of the anaesthetist, such as a tendency towards carbon-dioxide retention, a shift to the left in the oxyhaemoglobin dissociation curve, and a retardation in the elimination of non-volatile anaesthetic agents. Moreover, the heart-rate, cardiac output, and blood-pressure were all decreased, with a tendency to cardiac irregularities at levels around 25°C. Such irregularities presaged ventricular fibrillation ; and, because of this, continuous electrocardiographic control was, in Dr. Scurr’s opinion, essential. Sinus bradycardia with normal complexes had usually been seen in his cases.
chairmanship
suspended.
During rewarming " after-cooling might occur owing to the opening up of the peripheral circulation with the transfer of very cold blood to the main circulation. A "
-
"
sequeloe.. Dr. B. G. B. LucAS remarked on the difference between the tolerance of the brain and of the heartfor ischaemia during induced hypothermia. The heart was more susceptible under these conditions than the brain-a reversal of the order at normal temperature-which suggested that the future of very deep hypothermia might lie in methods of reducing heart work. Mr. C. E. DREW suggested that hypothermia was of great value for operations on congenitally cyanotic children, particularly when it was not possible to tell preoperatively what surgical procedure might be necessary. The antithrombotic effect was probably of value when an anastomosis was performed. Dr. G. J. REES (Liverpool) doubted whether hypothermia was ever of value for the Blalock shunt operation. He remembered anaesthetising a child with congenital heart-disease and cyanotic coma-a very severe casewith a successful outcome. He considered that if this was possible with a standard anaesthetic technique, then it was unnecessary to submit the child to further risks. "
’
".
ligated
condition remained satisfactory, and so the upper four ribs were removed to minimise the likelihood of subsequent mediastinal displacement.
general
Progress.-The postoperative course was singularly uneventful ; within a few days the patient’s general condition had
greatly improved and all signs of toxsemia had disappeared ; the blood-pressure became established at 120/60 mm. Hg, and the continuous murmur was replaced by a short low-pitched mid-systolic pulmonary bruit. The radiographic appearance fifteen days after operation is shown in fig. 2. At the time of publication, the patient remains in excellent health, has no cough or sputum, and does not complain of dyspnoea on ordinary exertion. She is up all day and will be discharged home in the next few weeks. Summary
Fig. 2-Radiograph
of chest fifteen
she developed a productive She was first lost weight. 1954.
days after operation.
cough, seen
felt very unwell, and one of us in May,
by
On examination her general condition was poor. There continuous murmur, together with a systolic thrill, in the second left intercostal space ; the blood-pressure was lOOi30 mm. Hg. There was no finger-clubbing. Radiography showed considerable spread of the tuberculous disease in the left upper lobe, where there was a large homogeneous oval opacity-evidently a blocked cavity-and there were scattered, though limited, fresh opacities in the right upper zone. The heart was not greatly enlarged, but screening in the left anterior oblique position revealed some prominence of the left ventricle. The sputum was positive for tubercle bacilli for the first time. On admission to High Carley Hospital on Aug. 2 her general condition had greatly deteriorated ; she was feverish and extremely ill, and radiographic examination (fig. 1) showed that the contents of the lesion in the left upper zone had been evacuated, leaving a large thick-walled cavity ; there was extensive bronchogenic spread of disease to the left lower
A woman, aged 35, with extensive pulmonary tuberculosis and patent ductus arteriosus, previously complicated by infective endarteritis, was successfully treated by combined ligation of the ductus, pneumonectomy, and
thoracoplasty
at
a
was a
zone,
mainly
to the
lingula.
REFERENCES
Conklin, W. S., Tuhy, J. E., Grismer, J. T. (1951) J. thorac. Surg. 22, 271. Crafoord, C. (1948) Brit. Heart J. 10, 71. Gross, R. E. (1947) J. thorac. Surg. 16, 314. Hubbard, J. P. (1939) J. Amer. med. Ass. 112, 729. Tuffier, M. (1891) Bull. Soc. anat., Paris, 66, 300. Wood, P. (1950) Diseases of the Heart and Circulation. London ; —
p. 228.
NEW SHORT-ACTING THIOBARBITURATE M.B. ANÆSTHETIC
PETER NOBES Lond., F.F.A. R.C.S., D.A.
REGISTRAR,
CHASE
ENFIELD GROUP OF
t
Treatment with postural rest and chemotherapy (streptomycin 1 g. daily and isoniazid 250 mg. daily) was begun, and after two months there was very striking improvement in her general condition. Radiography showed blocking of the large cavity in the left upper lobe, some slight contraction of the massive spread in the left lower zone, and almost complete disappearance of the small lesions in the right lung. Bronchoscopy revealed no sign of significant endobronchitis ; bloodcultures were repeatedly negative. At this stage-no doubt because of her considerable symptomatic improvement and numerous domestic anxietiesthe patient became very restless and it seemed unlikely that she would accept long-continued hospital treatment. We had therefore to consider immediate definitive treatment, for her condition was clearly still precarious. The risk of circulatory failure following pneumonectomy in the presence of a patent ductus with increased pulse-pressure was unquestionably grave. We therefore decided to do a thoracotomy, to ligate the ductus, and (if the patient’s condition was still satisfactory) to proceed there and then to resect the diseased lung-tissue. We calculated that the risk of bronchogenic dissemination of disease following thoracotomy would be considerable unless the tuberculous lesions could be dealt with at the same time. Operation (Nov. 1).-The dissection of the ductus was complicated by the presence of many adherent glands ; the vessel, the wall of which was not unduly thickened, was
single operation.
Our thanks are due to Dr. C. P. Brown, whose skill in anaesthesia made this operation possible, and to Dr. A. P. B. Waind, for information about the patient when she was under his care in 1952 for the treatment of infective endarteritis.
FARM
HOSPITAL
AND
THE
HOSPITALS, MIDDLESEX
IN anaesthesia for outpatients both hexobarbitone and sodium thiopentone have the great disadvantage that somnolence may persist after the operation. Weese and Koss (1954) and Dietman (1954) have described experimental and clinical experience with ’Baytenal,’ a new very short-acting anaesthetic, which is apparently eliminated from the body so rapidly that its administration is followed by little, if any, postoperative somnolence. This drug is sodium 5,5-allyl-(2-methyl-propyl)-thiobarbiturate. It is issued as a powder, which is readily soluble in water and is administered as a 10% solution, which, according to the manufacturers, is stable for thirty-six hours. It is not at present on sale in this
country. Weese and Koss (1954) based their observations 350
on
cases.
Their series included inpatients many of whom were ill and debilitated ; these were given premedication, but morphine and its derivatives were avoided. Outpatients were given no premedication and all types of surgical operation lasting up to 10 minutes were undertaken. In the average adult they injected 2-3 ml. of the 10% solution quite rapidly, and after about 11/2 minutes a further quantity, depending
798 TABLE I-FINDINGS WITH BAYTENAL IN FIVE INPATIENTS
the depth of narcosis or duration of operation. In no case did the total dose exceed 1 g. Where muscular relaxation was needed succinylcholine was administered. on
Weese and Koss emphasise that, because the freedom from subsequent excitement, the slight respiratory depression, and, above all, the very rapid elimination of this drug, the patients needed no supervision after operation ; there was no vomiting or other complication. Outpatients were able to leave the operating-theatre within a few minutes of the end of the operation, and to go home in 20-30 minutes. Clinical Trial
A clinical trial of baytenal has been undertaken at Chase Farm Hospital. Because little of the drug was available the series included only eleven patients. Their ages ranged from 17 to 62 ; and, in order to obtain an unobscured picture of the effects of the baytenal, cases were selected to exclude so far as possible those where the addition of long-acting relaxants, inhalational agents, or other intravenous drugs would be necessary. The inpatients, with one exception, received premedication with ’Omnopon ’ gr. 1/3 and seopolamine gr. 1/no’ The outpatients received no premedieation, with the exception of one who was given atropine gr. 1/100’ Baytenal was given mostly in a single dose, injected as rapidly as possible. The dose was estimated on the basis of the patient’s age, weight, and general condition and the probable duration of the operation. During anaesthesia some patients breathed air, while others received a nitrous-oxide/oxygen mixture at the rate of 5 and 2 litres per minute respectively either immediately following the injection or after several minutes where return of consciousness seemed likely before the end of the operation. Particular attention was directed to the duration of unconsciousness, judged by the time taken by the patients to register complete awareness of surroundings in response to questioning. The degree of respiratory depression, the time which elapsed before the patients were able to sit or walk unaided, and the presence or absence of excitement, amnesia, and nausea or vomiting were noted. The results are summarised in tables i and 11.
The blood-pressure was recorded and spirometry tracings taken by two observers. No premedication was given; the spirometer facepiece was applied, and time given to become accustomed to the apparatus. Baytenal 0-6 g. was given slowly over a period of 1 minutes. Rapid loss of consciousness occurred, preceded by a brief sensation of drowsiness; no taste was experienced. The blood-pressure fell from 138/90 to 120/80 mm. Hg and the pulse-rate rose from 72 per minute to 120 per minute. Very slight depression of respiratory amplitude was registered on the spirometer, but respiratory rate was unchanged. After a further P/2 minutes baytenal 0-4 g. was injected as quickly as possible. This injection was followed by a slight fall in both rate and volume of respiration, which returned to normal within 2 minutes. 2 minutes after this second injection a painful stimulus (digital pressure over the brachial plexus) caused increased depth and rate of respiration. 6 minutes after the initial injection the subject regained consciousness. He had no mental confusion whatever and was able to answer questions regarding time and place; there was no retrograde amnesia. After a further 6 minutes he was able to walk in a straight line, and within 22 minutes from the first injection was able to write an account of subjective sensations. The return to full consciousness was rapid, Slight euphoria persisted for about 2 hours ; but this in no way impaired the sense of wakefulness, nor the ability to drive a car and carry on with normal work within that period, This contrasted strongly with the 3-4 hours of pronounced somnolence experienced by the subject after 0-2 g. of sodium thiopentone a week previously. were
Discussion
The most striking feature in this series was the very short time in which patients regained normal conscious. ness with freedom from postansesthetic confusion or drowsiness. Equally important was the very short interval between recovery of consciousness and return of ability to sit, stand, and walk unaided. During anaesthesia respiratory depression was very slight, and in no case (except where succinylcholine was used) did apncea of more than a few seconds’ duration appear. Retching occurred in only three cases, and lasted for about 3 /.-1minute ; two of these three patients had received omnopon gr. 1/3 and scopolamine gr. 1/lso as premedication. In five cases a normal meal was taken within 2 hours after the anesthetic. It would seem that, if the " single-dose technique is used, at least 0-5 g. should be given to an adult patient. Baytenal may prove of special value for casualty or outpatient cases where it is particularly desired to avoid "
Experimental The
drug (P. N.).
was
administered
Observation
experimentally
to
a
volunteer
TABLE II-FINDINGS WITH BAYTENAL IN
SIX OUTPATIENTS
799 the
unpleasantness
of induction with
an
inhalation
anaesthetic, but where it is also important that the a very short time. Because of its rapid elimination it may be worth trying its administration by continuous drip infusion for longer operations. The contra-indications to sodium thiopentone should be applied equally to baytenal, though this drug causes less severe respiratory depression and may thus be more suitable for " poor risk " cases.
patient is ambulant within
Summary A new short-acting thiobarbiturate,Baytenal’ has been tested in eleven patients and in a healthy volunteer. This drug depresses respiration very slightly. It may prove particularly useful for anaesthesia in outpatients because of the rapid return of consciousness and the absence of postaneesthetic somnolence and confusion.
My thanks are due to Dr. P. W. S. Gray and Dr. D. Zuck, consultant anaesthetists to Chase Farm Hospital, for their help and encouragdment in the preparation of this paper. I am also grateful to Messrs. Bayer, of Leverkusen, Germany, for a
supply
of
Baytenal. REFERENCES
Dietman, K. (1954) Chirurg. 25, 185. Weese, H., Koss, F. H. (1954) Dtsch. med. Wschr. 79, 601.
Medical Societies ROYAL SOCIETY OF MEDICINE Induced
Hypothermia
further fall in the central temperature from this cause might lead to ventricular fibrillation and death. Dr. Scurr described how he induced hypothermia in small children under light anaesthesia and oxygen, perhaps with a muscle relaxant to prevent shivering. He used a cooling blanket through which circulated water at 2-4°C. Dr. T. C. GRAY (Liverpool) described the results of induced hypothermia in 110 patients, almost all adults. He advocated surface-cooling and demonstrated the technique with a colour film. Hypothermia was induced during light anaesthesia, with a muscle relaxant, and under the vasodilator effect of chlorpromazine. There was no shivering, and an adequate temperature fall could be obtained in one and a half hours. The tendency " towards an after-drop in temperature when active cooling ceased could be prevented by tilting the patient at fifteen-minute intervals, to prevent local accumulation of blood. Dr. Gray showed that this " after-drop " was most common in patients with a large surface-area whose temperature fell slowly during cooling. He thought that this technique was altogether more satisfactory than intravenous administration of a mixture of chlorpromazine, promethazine hydrochloride, and pethidine followed by surface-cooling, which was slow in effect and often complicated by shivering. He and his colleagues had used induced hypothermia for intrathoracic, neurosurgical, and general surgical operations. Hypothermia had also been produced therapeutically, but without conspicuous success. In neurosurgery its particular value seemed to be the increased safety with which induced hypotension could be used for long periods with the patient in the upright position, while in general surgery a low temperature seemed to offer some protection against the effects of surgical trauma ; this was most obvious in poor-risk patients. In the whole series of 110 cases there were 13 deaths. These were very poor-risk patients ; but 3 of the deaths among patients submitted to neurosurgical operations were from pulmonary embolus, and Dr. Gray thought there might be some significance in this. Attempts to measure the pituitary-adrenal responses of patients to surgical stress with and without induced hypothermia had not yet shown much difference, but from experimental work on dogs Dr. Gray thought there was evidence that these responses were modified to the ultimate benefit of the animal. In the discussion that followed, Dr. J. W. DUNDEE (Liverpool) remarked on the particular value of induced hypothermia for neurosurgical cases. In one case he described the surgeon had clamped the middle cerebral artery for seven and a half minutes without postoperative
THE anaesthetics section met on April 1, under the of Dr. BERNARD JOHNSON, president of the to discuss Induced Hypothermia. section, Dr. C. F. ScuRR observed that tissue anoxia due to circulatory arrest, unless rapidly relieved, led to cellular death ; but if the body-temperature was lowered cellular metabolism and oxygen demands were reduced, so the cells survived the anoxia for longer periods. A hypothermic technique might be valuable for intracardiac operations, for transposition of the great vessels, for operations for congenital cyanotic heart-disease, for certain intracranial operations, and for some abdominal and thoracic operations such as excision of an aortic aneurysm. There were five advantages to be gained. First, the oxygen requirements of the tissues were reduced, since if shivering was prevented oxygen consumption fell in a linear fashion with fall of body-temperature. Secondly, cardiac work was reduced. Thirdly, the coagulation-time of the blood was increased, which might be beneficial in certain types of cardiovascular surgery where thrombosis was a potential danger. Fourthly, anaesthetic requirements were reduced. Fifthly, harmful bacterial and enzyme activity was Dr. Scurr noted several disadvantages which necessitated special care on the part of the anaesthetist, such as a tendency towards carbon-dioxide retention, a shift to the left in the oxyhaemoglobin dissociation curve, and a retardation in the elimination of non-volatile anaesthetic agents. Moreover, the heart-rate, cardiac output, and blood-pressure were all decreased, with a tendency to cardiac irregularities at levels around 25°C. Such irregularities presaged ventricular fibrillation ; and, because of this, continuous electrocardiographic control was, in Dr. Scurr’s opinion, essential. Sinus bradycardia with normal complexes had usually been seen in his cases.
chairmanship
suspended.
During rewarming " after-cooling might occur owing to the opening up of the peripheral circulation with the transfer of very cold blood to the main circulation. A "
-
"
sequeloe.. Dr. B. G. B. LucAS remarked on the difference between the tolerance of the brain and of the heartfor ischaemia during induced hypothermia. The heart was more susceptible under these conditions than the brain-a reversal of the order at normal temperature-which suggested that the future of very deep hypothermia might lie in methods of reducing heart work. Mr. C. E. DREW suggested that hypothermia was of great value for operations on congenitally cyanotic children, particularly when it was not possible to tell preoperatively what surgical procedure might be necessary. The antithrombotic effect was probably of value when an anastomosis was performed. Dr. G. J. REES (Liverpool) doubted whether hypothermia was ever of value for the Blalock shunt operation. He remembered anaesthetising a child with congenital heart-disease and cyanotic coma-a very severe casewith a successful outcome. He considered that if this was possible with a standard anaesthetic technique, then it was unnecessary to submit the child to further risks. "
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