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ANÆSTHESIA FOR NEUROSURGERY
ANESTHESIA FOR NEUROSURGERY WITH SPECIAL REFERENCE TO TRICHLORETHYLENE BY PHILIP AYRE,
M.R.C.S. (Eng.), L.R.C.P. (Lond.),. Newcastle-upon-Tyne
prejudice the ultimate recovery of the patient. It is most important, therefore, that vascular congestion should be reduced to the minimum, and for this reason methods of anaesthesia which give every satisfaction in other branches of surgery may require modification before they are suitable for neurosurgical procedures. Even with the most expert administration nitrous oxideoxygen may in certain cases lead to vascular congestion and peripheral venous oozing. Two factors are responsible for this (i) there may be accumulation of excess C0 2 in the rebreathing-bag, and (2) the patient exhales against the resistance of the rebreathing-bag and spring-loaded expiratory valve. Admittedly the resistance may be very small, but in certain circumstances it tends to raise the intrathoracic pressure and partially obstruct the venous return to the left heart, resulting in vascular congestion and venous oozing at the site of operation. The degree in which this may be present varies according to the amount of respiratory obstruction present, the state of the patient's cardiovascular system, the nature of the operation and the efficiency or otherwise of the anaesthetic apparatus. During an abdominal operation haemorrhage may be negligible, but when vascular parts such as the breast or perineum are involved it may be so profuse as to arouse misgivings in the mind of the most bigoted gas-oxygen (or cyclopropane) enthusiast. The surB
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
URING a surgical operation on the brain or spinal D cord haemorrhage not only adds greatly to the technical difficulties encountered by the surgeon, but may seriously
18
British Journal of Anaesthesia
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geon usually has no doubts about the cause of the haemorrhage, and is apt to make sarcastic references to the " good old days " of open ether and chloroform. Even when the CO, absorption technique is employed increased bleeding may still be present, especially towards the end of the operation when the skin and underlying tissues are being sutured. Whether this is due to the soda-lime losing its efficiency, "straining" under light anaesthesia, or a rise in bloodpressure following closure of the abdominal cavity, one fact cannot be disputed—vascular congestion and haemorrhage are definitely less when " o p e n " methods of anaesthetic administration are employed. Apart from the question of venous oozing, nitrous oxideoxygen has many disadvantages from the point of view of the neurosurgeon. Unless full doses of morphia, scopolamine, tribromethanol or other depressant drugs are previously administered, it is not possible to maintain anaesthesia without anoxaemia. On the other hand, morphia and basal narcotics depress the vital centres in the medulla to an extent which may be dangerous, especially when the intracranial pressure is already raised by injury or disease. Moreover, the prolonged postoperative sleep which often follows the use of these drugs may mask important cerebral symptoms which would otherwise be recognized in time. During the last eight years the majority of cases in the Neurosurgical Department of the Newcastle-upon-Tyne General Hospital have been anaesthetized by the "open " T-piece technique,1 in which the rebreathing-bag is replaced by a rubber tube open to the air at one end and connected to the intratracheal tube at the other. Through the transverse limb of a metal T-piece incorporated in the rubber tubing, nitrous oxide-oxygen supplemented by ether or other volatile anaesthetic is "injected" into the system. Theoretically it might seem impracticable to administer nitrous oxide with the circuit open to the air; but, in practice, a light plane of anaesthesia can be maintained indefinitely by adjusting the flow of nitrous oxide to 2 to 4 litres with oxygen i£ to 2 litres a minute, the gases being supplemented by minimal quantities of ether or chloroform. So marked is the absence of vascular congestion with the T-piece technique
Anaesthesia for Neurosurgery
19
DESCRIPTION OF TECHNIQUE
When preparing the patient for a neurosurgical operation it is most important that starvation and violent purgation should be avoided. If the operation has been arranged for the afternoon a light breakfast may be allowed in the morning supplemented by a cup of soup or meat extract at midday. It is wise to administer glucose in one form or another during the preceding 24 hours, especially in the case of children. If the patient cannot sleep a barbiturate or other mild hypnotic may be given in the evening before operation, but often this is unnecessary. One hour before the time of operation the patient is given a hypodermic injection of Omnopon (pantopon) gr. 1/3 with Atropine gr. 1/100. On arriving at the anaesthetic anteroom the throat and vocal cords are sprayed with 2 per cent Decicain (Pantocain) or Nupercaine: this helps to eliminate straining or coughing—another cause of vascular conges-
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
that the present Surgeon in Charge of the Neurosurgical Department refuses to allow any other method, although for many years his cases were anaesthetized (in another clinic) by more orthodox methods involving the use of tribromethanol and nitrous oxide-oxygen administered by the closed or semi-closed technique. Until a year ago ether or chloroform was used as the supplementary agent, and despite the bad reputation of the latter drug the condition of the patients both during operation and afterwards was excellent in every respect. However, it must be admitted that considerable judgment is required to administer chloroform successfully, and in the hands of an incompetent or inexperienced anaesthetist it may be anything but safe. A year or two ago Langton Hewer2 introduced trichlorethylene as a general anaesthetic, and it seemed that here might be a non-inflammable agent suitable for use with diathermy apparatus and without the potential dangers associated with chloroform. This proved to be the case, and since July 1942 105 patients undergoing operation on the brain or spinal cord have been anaesthetized with trichlorethylene, with such good results that this agent is now used as a routine for neurosurgical cases.
20
British Journal of Anaesthesia
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u'on3—during the early stages of the operation. In most cases anaesthesia is induced by intravenous injection of 5 per cent Pentothal Sodium, the amount varying from 4 to 10 c.c. according to the physical condition of the patient. Nitrous oxide-oxygen and trichlorethylene are administered by the orthodox semi-closed technique until the jaw is sufficiently relaxed to insert a Magill tube into the trachea; this is preferably carried out orally under direct vision laryngoscopy. Anaesthesia is continued until the patient is firmly established in the first plane of the third stage, when the rebreathing-bag is removed and replaced by the T-piece attachment. To the distal or open end of the latter is attached a length of widebore (internal diameter 1 cm. approx.) rubber tubing. The exact length of the rubber tubing is not important and may be varied to suit the conditions; for adults 3 to 3^ feet will be about right, especially in neurosurgical cases where the anaesthetist has to work at a distance from the site of operation. Finally, the mouth is packed off with gauze wrung out in liquid paraffin. During the operation the flow of gases is adjusted so that the minute volume of nitrous oxide is 2 to 4 litres with oxygen 2 litres, the gases being allowed to flow over the surface of the trichlorethylene—it is rarely necessary to " bubble through " the liquid. In the case of exceptionally resistant patients a little ether may be given for ten minutes until the patient has settled down. The average quantity of trichlorethylene required to maintain anaesthesia in the first plane varies from 2 to 4 drachms an hour, although rather more than this may be needed during the first hour while the bone flap is being trephined. After the dura has been opened and the brain exposed, the nitrous oxide is usually discontinued, the flow of oxygen being increased to 4 litres a minute, and trichlorethylene administered intermittently. With practice it is surprising how little anaesthetic is needed to maintain adequate anaesthesia, and not infrequently on removing the intratracheal tube at the end of the operation the patient will open his eyes and reply to questions. Indeed, if the patient is still deeply asleep and the superficial reflexes are absent, it is highly probable that some cerebral complication (e.g. a blood clot) has arisen.
Anaesthesia for Neurosurgery
21
While the operation is in progress routine observations should be taken of the blood-pressure, pulse and respiration. The latter may conveniently be observed by affixing a single strand of gauze to the distal end of the rubber tubing: this will wave to and fro with the patient's respirations. It is also wise to set up an intravenous " drip " during the early part of the operation, so that plasma or whole blood may be given without unnecessary delay. CASE RECORDS
Brain tumour Brain abscess Nerve root section Laminectomy Head injuries Miscellaneous
-
35 3 12
...
25
...
15
15
These figures represent cases anaesthetized by the writer and do not include those done by other members of the anaesthetic staff, who also used trichlorethylene with equally good results. In fact one of the great advantages of the T-piece method is that once the intratracheal tube is in position the patient can be safely left with a junior housesurgeon or nurse. It is practically impossible for any harm to come to the patient; even if the oxygen supply should inadvertently run out the patient can still inhale air through the T-piece until the deficiency has been rectified. The following are case reports and anaesthetic charts of four patients undergoing neurosurgical operations. CASE I . A woman, aged 64, in bad physical condition (grade 3) and suffering from a tumour in the right cerebral hemisphere. Clinical data. Blood-pressure 150/95; pulse 120. Cachetic and dehydrated. Premeditation. Atropine, gr. 1/200.
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During a period of twelve months, commencing in July 1942, a total of 105 neurosurgical patients were anaesthetized with nitrous oxide-oxygen and air supplemented by trichlorethylene. These may be subdivided as follows:
22
British Journal of Anaesthesia
Induction. Nitrous oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Local infiltration of scalp with procaine. Operation (September gth, 1942). Partial extirpation of large meningioma. Operation lasted three hours and twenty minutes during which one ounce and three drachms of trichlorethylene were administered. Ten minutes after the operation was ended the patient replied to questions. Blood-pressure, 125/85; pulse 135. No pallor or sweating. Progress. Vomited more than usual, possibly owing to poor physical condition. Fairly well the next morning and was discharged from hospital one week later. Comments. Respirations averaged 30 to 35 during operation, but otherwise anaesthesia was tranquil and free from vascular congestion. One pint of plasma was administered intravenously during operation. Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
CASE 2. A female child, aged 6, in bad physical condition (grade 3), suffering from a tumour of the cerebellum. Under weight and poor physique. Due to raised intracranial pressure she was flushed and irritable, with a slow pulse, irregular in rate and force. Clinical data. Blood-pressure, 95/65; pulse 50 (75 after atropine). Premedication. Atropine, gr. 1/200. Induction. Oxygen-nitrous oxide and trichlorethylene. Maintenance. .Oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Local infiltration. Operation (February 1st, 1943). Removal of cystic glioma in midline of cerebellum. No special difficulties encountered during operation which lasted four hours. At end of operation child was moving and superficial reflexes were present. General condition very fair. Blood-pressure, 85/58; pulse-rate 140. Good colour. No sweating. Comments. Respirations averaged 30 to 40. Any increase in trichlorethylene, which was given intermittently throughout, tended to increase rate of respiration. Pulse regular and not unduly rapid until after removal of tumour, when it rose to 140. One pint of plasma was given intravenously during operation. Special note. No anxiety was experienced regarding the use of trichlorethylene in this case; but ether would have been substituted if the rate of respiration had risen any further, or if the pulse had become irregular. Seven drachms of triohlorethylene were used. Progress. No vomiting or other complication. Child was discharged from hospital about three weeks later.
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Anaesthesia for Neurosurgery
27
CASE 4. A middle-aged man, 50, in fair general condition (grade 2), with three years history of headache and vomiting due to a tumour of the cerebellum. Clinical data. Blood-pressure 140/100; pulse-rate 128 (after preBiedication). Physique and weight normal. Slight chronic bronchitis. Premedication. Omnopon gr. 4, with atropine gr. 1 /100. Induction. Pentothal sodium, six c.c. of 5 per cent solution. Nitrous Operation (May 31st, 1943). Removal of cystic astrocytoma from oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and triohlorethylene. Technique. Oral intubation. " Open " T-piece. Local infiltration, left lobe of cerebellum. One and three-quarter ounces of trichlorethylene were given over a period of four hours and ten minutes. At the
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
CASE 3. A young man, aged 17, injured b,y hand-grenade exploding prematurely during Home Guard exercises. When admitted to hospital lie was pale, semicomatose and incontinent. It was discovered that a large portion of the bolt of a rifle had entered through the left orbit, and was firmly embedded in the brain at the base of the skull. Apart from shock due to the injury he was in good general condition. Bloodpressure, 140/40; pulse-rate 62. Premedication. Omnopon gr. 3, with atropine gr. 1 /100. Induction. Nitrous oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Operation (April 4th, 1943). Foreign body could be seen through erbit and also through hole in skull. Eventually removed with considerable force through orbital wound. Operation lasted three hours during which ij^ ounces of trichlorethylene were used. Condition of patient at close was good. Superficial reflexes present. Blood-pressure 132/60; pulse-rate 106. Good colour. No sweating. Comments. Respirations averaged 20 to 27. Anaesthesia satisfactory. One pint of plasma given intravenously during operation. Progress. No vomiting or other complication. Went home six •weeks later apparently healed and well. Two weeks later he unfortanately developed meningitis following a cold, and was readmitted to hospital in status epilepticus. Died a few days later. Post-mortem revealed a defect in the inner aspect of the orbit with perforated cribiform plate on the left side. The optic nerve was severed and there was a large laceration in the left frontal lobe of the brain. The left and part of the right side of the cribiform plate were missing, and the brain was protruding through the gap.
28
British Journal of Anaesthesia
EFFECT OF TRICHLORETHYLENE ON RESPIRATION
In the series of 105 neurosurgical cases under review, the maximum rate of respiration was as follows: 0 21 31 41 51
Rate Number of cases to 20 per minute 14 to 30 ,, 47 to 40 ,, 34 to 50 6 to 60 4
From the above figures it will be seen that in approximately 60 per cent of cases the rate of respiration was below 30, in 30 per cent it was between 30 and 40, and in 10 per cent of cases it exceeded 40 per minute. Although as yet only one explanation* has been offered as to why the respiratory rate should increase in this manner, no harm seems to come to the patient, nor is any inconvenience caused to the surgeon as a rule. Of the ten cases when the rate of respiration exceeded 40, two were children under six years of age, three were in poor physical condition due to toxaemia or malignant cachexia and one was an obese short-necked man of 64 suffering from chronic bronchitis and emphysema.
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end of the operation the patient was moving and groaning. Bloodpressure 130/90; pulse 90. No pallor or sweating. Comments. Owing to the very high intracranial pressure in this case the patient was unduly depressed during induction of anaesthesia, and oral intubation was performed during a period of apnoea. Controlled respiration immediately restored normal breathing, and no further difficulty was experienced during the operation. Respirations averaged 8 to 10 during the first 2% hours and were periodic and apneustic in character. After a cyst in the left lobe of the cerebellum had been tapped, respirations improved to 18 for the remainder of the operation. Nearly a pint of plasma and a pint of blood were given intravenously. Special note. Possibly an error of judgment was made in giving this patient both Omnopon and Pentothal, in view of the high intracranial pressure before operation. Progress. Patient recovered consciousness half an hour after leaving the theatre. No vomiting or chest complications. Convalescence was normal.
Anaesthesia for Neurosurgery
29
CARDIAC IRREGULARITIES DUE TO TRICHLORETHYLENE
POSTOPERATIVE COMPLICATIONS
Owing to pressure of work and war difficulties detailed information concerning postoperative vomiting was not obtained in every case. In the majority of cases vomiting was slight or absent, and only on a very few occasions did
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Considerable discussion* has arisen regarding the effect of trichlorethylene on the conducting tissue and muscle of the heart. In the present series only two cases occurred in which the cardiac condition gave rise to anxiety. Both were elderly women in very bad physical condition (grade 4), and undergoing operation for brain tumour. In one case a 2:1 heart block (Pauricular flutter) persisted until the trichlorethylene was discontinued. In the other case the pulse became very irregular shortly after induction of anaesthesia: in spite of ether being substituted for trichlorethylene the irregularity persisted for an hour and a half, when the pulse improved. Trichlorethylene was again administered cautiously, but the pulse remained regular and there was no further change during the remainder of the operation. In neither of these cases was there any alteration in respiration or blood-pressure associated with the cardiac irregularities. Apart from these two cases minor cardiac irregularities were observed on five other occasions, bringing the number of cardiac complications up to seven or a little over 6 per cent of the total. One patient had a few extra-systoles following local infiltration of the scalp with procaine containing adrenaline—the only occasion on which adrenaline appeared to have any effect on the pulse during trichlorethylene anaesthesia. Persistent bradycardia, as reported by Gordon and Shackleton,6 was not present on any occasion. It should be mentioned, however, that in the present series the depth of anaesthesia never descended below the first plane of the third stage, which possibly accounts for the low incidence of cardiac irregularities observed. Unfortunately, electrocardiograph studies were not obtained.
30
British Journal of Anaesthesia
patients complain of nausea after operation. One patient developed a postoperative atelectasis involving the lower lobe of the left lung: owing to technical difficulties caused by kinking of the intratracheal tube, the respirations were somewhat laboured during the course of the operation, and it is probable that trichlorethylene was not to blame on this occasion. An epileptic patient with chronic bronchitis had a cough accompanied by pyrexia for a few days following operation. Apart from these two cases there were no chest complications due to trichlorethylene. Postoperative recovery was rapid, and most patients were fully conscious, within an hour from the time the operation ended. COMMENTS AND CONCLUSIONS Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
Trichlorethylene provides a safe and pleasant anaesthesia for neurosurgical operations, most of which require little more than analgesia. By using the " open " T-piece technique anaesthesia is tranquil and free from vascular congestion. Possibly because air is admitted to the system and there is no accumulation of anaesthetic, cardiac irregularities are few and the rate of respiration is not unduly rapid. From reports published it is evident that most of the difficulties encountered are associated with closed methods of administration, in which the anaesthetic concentration may rise to a higher level than when an open method is employed. Trichlorethylene should be used with caution in the case of young children or patients suffering from toxaemia or heart disease. It is especially suitable for operations where a light plane of anaesthesia is required; when deep anaesthesia is necessary, cyclopropane or ether is better from every point of view. When the services of a skilled anaesthetist are available almost any neurosurgical operation (except closed head injuries) can be performed under general anaesthesia with benefit to all concerned. For minor procedures continuous intravenous Pentothal Sodium is very useful, providing care is taken to maintain a free airway. If the anaesthetist is prepared to support the patient's jaw for four hours, this method may also be used for major operations; but it is
Anaesthesia for Neurosurgery
31
doubtful whether the results are worth the trouble. In suitable cases rectal Pentothal (1 gm. per 50 lbs. body weight) forms a pleasant method of inducing anaesthesia in young children, especially for encephalograms, or " cleaning up " and suturing scalp wounds. Recently a technique has been described' in which rectal tribromethanol supplemented by intravenous Pentothal Sodium is the anaesthetic of choice for neurosurgical operations: this method has attractive possibilities but it is not stated whether difficulties are encountered in maintaining a free airway. In concluding this paper I wish to acknowledge the help and encouragement which I have received from Mr. G. F. Rowbotham, Surgeon in Charge of the Neurosurgical Department at the Newcastle-upon-Tyne General Hospital.
1. Ayre, T. P. Lancet. March 6th, 1937, p. 561. 2. Hewer, C. L. Proceedings of the Royal Society of Medicine (Anaesthetic Section), March 6th, 1942; also " Recent Advances in Anaesthesia and Analgesia," 4th edition, chapter VII. 3. Brennan, H. J. Lancet, February 5th, 1938, p. 315. 4. Culbert, T. D. Brit. Med. Journ., May 8th, 1943, p. 582. 5. Waters, R. M., O. S. Orth, and N. A. Gillespie. Anesthesiology, January 1943, Vol. IV, No. 1. 6. Gordon, R. A., and R. P. W. Shackleton. Brit. Med. Journ., March 27th, 1943, p. 380. 7. Durshordwe, Clarence J. Current Researches in Anesthesia and Analgesia, March, 1942, Vol, 21, No. 2, p. 61.
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REFERENCES
M.R.C.S. (Eng.), L.R.C.P. (Lond.),. Newcastle-upon-Tyne
prejudice the ultimate recovery of the patient. It is most important, therefore, that vascular congestion should be reduced to the minimum, and for this reason methods of anaesthesia which give every satisfaction in other branches of surgery may require modification before they are suitable for neurosurgical procedures. Even with the most expert administration nitrous oxideoxygen may in certain cases lead to vascular congestion and peripheral venous oozing. Two factors are responsible for this (i) there may be accumulation of excess C0 2 in the rebreathing-bag, and (2) the patient exhales against the resistance of the rebreathing-bag and spring-loaded expiratory valve. Admittedly the resistance may be very small, but in certain circumstances it tends to raise the intrathoracic pressure and partially obstruct the venous return to the left heart, resulting in vascular congestion and venous oozing at the site of operation. The degree in which this may be present varies according to the amount of respiratory obstruction present, the state of the patient's cardiovascular system, the nature of the operation and the efficiency or otherwise of the anaesthetic apparatus. During an abdominal operation haemorrhage may be negligible, but when vascular parts such as the breast or perineum are involved it may be so profuse as to arouse misgivings in the mind of the most bigoted gas-oxygen (or cyclopropane) enthusiast. The surB
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
URING a surgical operation on the brain or spinal D cord haemorrhage not only adds greatly to the technical difficulties encountered by the surgeon, but may seriously
18
British Journal of Anaesthesia
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
geon usually has no doubts about the cause of the haemorrhage, and is apt to make sarcastic references to the " good old days " of open ether and chloroform. Even when the CO, absorption technique is employed increased bleeding may still be present, especially towards the end of the operation when the skin and underlying tissues are being sutured. Whether this is due to the soda-lime losing its efficiency, "straining" under light anaesthesia, or a rise in bloodpressure following closure of the abdominal cavity, one fact cannot be disputed—vascular congestion and haemorrhage are definitely less when " o p e n " methods of anaesthetic administration are employed. Apart from the question of venous oozing, nitrous oxideoxygen has many disadvantages from the point of view of the neurosurgeon. Unless full doses of morphia, scopolamine, tribromethanol or other depressant drugs are previously administered, it is not possible to maintain anaesthesia without anoxaemia. On the other hand, morphia and basal narcotics depress the vital centres in the medulla to an extent which may be dangerous, especially when the intracranial pressure is already raised by injury or disease. Moreover, the prolonged postoperative sleep which often follows the use of these drugs may mask important cerebral symptoms which would otherwise be recognized in time. During the last eight years the majority of cases in the Neurosurgical Department of the Newcastle-upon-Tyne General Hospital have been anaesthetized by the "open " T-piece technique,1 in which the rebreathing-bag is replaced by a rubber tube open to the air at one end and connected to the intratracheal tube at the other. Through the transverse limb of a metal T-piece incorporated in the rubber tubing, nitrous oxide-oxygen supplemented by ether or other volatile anaesthetic is "injected" into the system. Theoretically it might seem impracticable to administer nitrous oxide with the circuit open to the air; but, in practice, a light plane of anaesthesia can be maintained indefinitely by adjusting the flow of nitrous oxide to 2 to 4 litres with oxygen i£ to 2 litres a minute, the gases being supplemented by minimal quantities of ether or chloroform. So marked is the absence of vascular congestion with the T-piece technique
Anaesthesia for Neurosurgery
19
DESCRIPTION OF TECHNIQUE
When preparing the patient for a neurosurgical operation it is most important that starvation and violent purgation should be avoided. If the operation has been arranged for the afternoon a light breakfast may be allowed in the morning supplemented by a cup of soup or meat extract at midday. It is wise to administer glucose in one form or another during the preceding 24 hours, especially in the case of children. If the patient cannot sleep a barbiturate or other mild hypnotic may be given in the evening before operation, but often this is unnecessary. One hour before the time of operation the patient is given a hypodermic injection of Omnopon (pantopon) gr. 1/3 with Atropine gr. 1/100. On arriving at the anaesthetic anteroom the throat and vocal cords are sprayed with 2 per cent Decicain (Pantocain) or Nupercaine: this helps to eliminate straining or coughing—another cause of vascular conges-
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
that the present Surgeon in Charge of the Neurosurgical Department refuses to allow any other method, although for many years his cases were anaesthetized (in another clinic) by more orthodox methods involving the use of tribromethanol and nitrous oxide-oxygen administered by the closed or semi-closed technique. Until a year ago ether or chloroform was used as the supplementary agent, and despite the bad reputation of the latter drug the condition of the patients both during operation and afterwards was excellent in every respect. However, it must be admitted that considerable judgment is required to administer chloroform successfully, and in the hands of an incompetent or inexperienced anaesthetist it may be anything but safe. A year or two ago Langton Hewer2 introduced trichlorethylene as a general anaesthetic, and it seemed that here might be a non-inflammable agent suitable for use with diathermy apparatus and without the potential dangers associated with chloroform. This proved to be the case, and since July 1942 105 patients undergoing operation on the brain or spinal cord have been anaesthetized with trichlorethylene, with such good results that this agent is now used as a routine for neurosurgical cases.
20
British Journal of Anaesthesia
Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
u'on3—during the early stages of the operation. In most cases anaesthesia is induced by intravenous injection of 5 per cent Pentothal Sodium, the amount varying from 4 to 10 c.c. according to the physical condition of the patient. Nitrous oxide-oxygen and trichlorethylene are administered by the orthodox semi-closed technique until the jaw is sufficiently relaxed to insert a Magill tube into the trachea; this is preferably carried out orally under direct vision laryngoscopy. Anaesthesia is continued until the patient is firmly established in the first plane of the third stage, when the rebreathing-bag is removed and replaced by the T-piece attachment. To the distal or open end of the latter is attached a length of widebore (internal diameter 1 cm. approx.) rubber tubing. The exact length of the rubber tubing is not important and may be varied to suit the conditions; for adults 3 to 3^ feet will be about right, especially in neurosurgical cases where the anaesthetist has to work at a distance from the site of operation. Finally, the mouth is packed off with gauze wrung out in liquid paraffin. During the operation the flow of gases is adjusted so that the minute volume of nitrous oxide is 2 to 4 litres with oxygen 2 litres, the gases being allowed to flow over the surface of the trichlorethylene—it is rarely necessary to " bubble through " the liquid. In the case of exceptionally resistant patients a little ether may be given for ten minutes until the patient has settled down. The average quantity of trichlorethylene required to maintain anaesthesia in the first plane varies from 2 to 4 drachms an hour, although rather more than this may be needed during the first hour while the bone flap is being trephined. After the dura has been opened and the brain exposed, the nitrous oxide is usually discontinued, the flow of oxygen being increased to 4 litres a minute, and trichlorethylene administered intermittently. With practice it is surprising how little anaesthetic is needed to maintain adequate anaesthesia, and not infrequently on removing the intratracheal tube at the end of the operation the patient will open his eyes and reply to questions. Indeed, if the patient is still deeply asleep and the superficial reflexes are absent, it is highly probable that some cerebral complication (e.g. a blood clot) has arisen.
Anaesthesia for Neurosurgery
21
While the operation is in progress routine observations should be taken of the blood-pressure, pulse and respiration. The latter may conveniently be observed by affixing a single strand of gauze to the distal end of the rubber tubing: this will wave to and fro with the patient's respirations. It is also wise to set up an intravenous " drip " during the early part of the operation, so that plasma or whole blood may be given without unnecessary delay. CASE RECORDS
Brain tumour Brain abscess Nerve root section Laminectomy Head injuries Miscellaneous
-
35 3 12
...
25
...
15
15
These figures represent cases anaesthetized by the writer and do not include those done by other members of the anaesthetic staff, who also used trichlorethylene with equally good results. In fact one of the great advantages of the T-piece method is that once the intratracheal tube is in position the patient can be safely left with a junior housesurgeon or nurse. It is practically impossible for any harm to come to the patient; even if the oxygen supply should inadvertently run out the patient can still inhale air through the T-piece until the deficiency has been rectified. The following are case reports and anaesthetic charts of four patients undergoing neurosurgical operations. CASE I . A woman, aged 64, in bad physical condition (grade 3) and suffering from a tumour in the right cerebral hemisphere. Clinical data. Blood-pressure 150/95; pulse 120. Cachetic and dehydrated. Premeditation. Atropine, gr. 1/200.
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During a period of twelve months, commencing in July 1942, a total of 105 neurosurgical patients were anaesthetized with nitrous oxide-oxygen and air supplemented by trichlorethylene. These may be subdivided as follows:
22
British Journal of Anaesthesia
Induction. Nitrous oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Local infiltration of scalp with procaine. Operation (September gth, 1942). Partial extirpation of large meningioma. Operation lasted three hours and twenty minutes during which one ounce and three drachms of trichlorethylene were administered. Ten minutes after the operation was ended the patient replied to questions. Blood-pressure, 125/85; pulse 135. No pallor or sweating. Progress. Vomited more than usual, possibly owing to poor physical condition. Fairly well the next morning and was discharged from hospital one week later. Comments. Respirations averaged 30 to 35 during operation, but otherwise anaesthesia was tranquil and free from vascular congestion. One pint of plasma was administered intravenously during operation. Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
CASE 2. A female child, aged 6, in bad physical condition (grade 3), suffering from a tumour of the cerebellum. Under weight and poor physique. Due to raised intracranial pressure she was flushed and irritable, with a slow pulse, irregular in rate and force. Clinical data. Blood-pressure, 95/65; pulse 50 (75 after atropine). Premedication. Atropine, gr. 1/200. Induction. Oxygen-nitrous oxide and trichlorethylene. Maintenance. .Oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Local infiltration. Operation (February 1st, 1943). Removal of cystic glioma in midline of cerebellum. No special difficulties encountered during operation which lasted four hours. At end of operation child was moving and superficial reflexes were present. General condition very fair. Blood-pressure, 85/58; pulse-rate 140. Good colour. No sweating. Comments. Respirations averaged 30 to 40. Any increase in trichlorethylene, which was given intermittently throughout, tended to increase rate of respiration. Pulse regular and not unduly rapid until after removal of tumour, when it rose to 140. One pint of plasma was given intravenously during operation. Special note. No anxiety was experienced regarding the use of trichlorethylene in this case; but ether would have been substituted if the rate of respiration had risen any further, or if the pulse had become irregular. Seven drachms of triohlorethylene were used. Progress. No vomiting or other complication. Child was discharged from hospital about three weeks later.
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Anaesthesia for Neurosurgery
27
CASE 4. A middle-aged man, 50, in fair general condition (grade 2), with three years history of headache and vomiting due to a tumour of the cerebellum. Clinical data. Blood-pressure 140/100; pulse-rate 128 (after preBiedication). Physique and weight normal. Slight chronic bronchitis. Premedication. Omnopon gr. 4, with atropine gr. 1 /100. Induction. Pentothal sodium, six c.c. of 5 per cent solution. Nitrous Operation (May 31st, 1943). Removal of cystic astrocytoma from oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and triohlorethylene. Technique. Oral intubation. " Open " T-piece. Local infiltration, left lobe of cerebellum. One and three-quarter ounces of trichlorethylene were given over a period of four hours and ten minutes. At the
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CASE 3. A young man, aged 17, injured b,y hand-grenade exploding prematurely during Home Guard exercises. When admitted to hospital lie was pale, semicomatose and incontinent. It was discovered that a large portion of the bolt of a rifle had entered through the left orbit, and was firmly embedded in the brain at the base of the skull. Apart from shock due to the injury he was in good general condition. Bloodpressure, 140/40; pulse-rate 62. Premedication. Omnopon gr. 3, with atropine gr. 1 /100. Induction. Nitrous oxide-oxygen and trichlorethylene. Maintenance. Nitrous oxide-oxygen-air and trichlorethylene. Technique. Oral intubation and " open " T-piece. Operation (April 4th, 1943). Foreign body could be seen through erbit and also through hole in skull. Eventually removed with considerable force through orbital wound. Operation lasted three hours during which ij^ ounces of trichlorethylene were used. Condition of patient at close was good. Superficial reflexes present. Blood-pressure 132/60; pulse-rate 106. Good colour. No sweating. Comments. Respirations averaged 20 to 27. Anaesthesia satisfactory. One pint of plasma given intravenously during operation. Progress. No vomiting or other complication. Went home six •weeks later apparently healed and well. Two weeks later he unfortanately developed meningitis following a cold, and was readmitted to hospital in status epilepticus. Died a few days later. Post-mortem revealed a defect in the inner aspect of the orbit with perforated cribiform plate on the left side. The optic nerve was severed and there was a large laceration in the left frontal lobe of the brain. The left and part of the right side of the cribiform plate were missing, and the brain was protruding through the gap.
28
British Journal of Anaesthesia
EFFECT OF TRICHLORETHYLENE ON RESPIRATION
In the series of 105 neurosurgical cases under review, the maximum rate of respiration was as follows: 0 21 31 41 51
Rate Number of cases to 20 per minute 14 to 30 ,, 47 to 40 ,, 34 to 50 6 to 60 4
From the above figures it will be seen that in approximately 60 per cent of cases the rate of respiration was below 30, in 30 per cent it was between 30 and 40, and in 10 per cent of cases it exceeded 40 per minute. Although as yet only one explanation* has been offered as to why the respiratory rate should increase in this manner, no harm seems to come to the patient, nor is any inconvenience caused to the surgeon as a rule. Of the ten cases when the rate of respiration exceeded 40, two were children under six years of age, three were in poor physical condition due to toxaemia or malignant cachexia and one was an obese short-necked man of 64 suffering from chronic bronchitis and emphysema.
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end of the operation the patient was moving and groaning. Bloodpressure 130/90; pulse 90. No pallor or sweating. Comments. Owing to the very high intracranial pressure in this case the patient was unduly depressed during induction of anaesthesia, and oral intubation was performed during a period of apnoea. Controlled respiration immediately restored normal breathing, and no further difficulty was experienced during the operation. Respirations averaged 8 to 10 during the first 2% hours and were periodic and apneustic in character. After a cyst in the left lobe of the cerebellum had been tapped, respirations improved to 18 for the remainder of the operation. Nearly a pint of plasma and a pint of blood were given intravenously. Special note. Possibly an error of judgment was made in giving this patient both Omnopon and Pentothal, in view of the high intracranial pressure before operation. Progress. Patient recovered consciousness half an hour after leaving the theatre. No vomiting or chest complications. Convalescence was normal.
Anaesthesia for Neurosurgery
29
CARDIAC IRREGULARITIES DUE TO TRICHLORETHYLENE
POSTOPERATIVE COMPLICATIONS
Owing to pressure of work and war difficulties detailed information concerning postoperative vomiting was not obtained in every case. In the majority of cases vomiting was slight or absent, and only on a very few occasions did
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Considerable discussion* has arisen regarding the effect of trichlorethylene on the conducting tissue and muscle of the heart. In the present series only two cases occurred in which the cardiac condition gave rise to anxiety. Both were elderly women in very bad physical condition (grade 4), and undergoing operation for brain tumour. In one case a 2:1 heart block (Pauricular flutter) persisted until the trichlorethylene was discontinued. In the other case the pulse became very irregular shortly after induction of anaesthesia: in spite of ether being substituted for trichlorethylene the irregularity persisted for an hour and a half, when the pulse improved. Trichlorethylene was again administered cautiously, but the pulse remained regular and there was no further change during the remainder of the operation. In neither of these cases was there any alteration in respiration or blood-pressure associated with the cardiac irregularities. Apart from these two cases minor cardiac irregularities were observed on five other occasions, bringing the number of cardiac complications up to seven or a little over 6 per cent of the total. One patient had a few extra-systoles following local infiltration of the scalp with procaine containing adrenaline—the only occasion on which adrenaline appeared to have any effect on the pulse during trichlorethylene anaesthesia. Persistent bradycardia, as reported by Gordon and Shackleton,6 was not present on any occasion. It should be mentioned, however, that in the present series the depth of anaesthesia never descended below the first plane of the third stage, which possibly accounts for the low incidence of cardiac irregularities observed. Unfortunately, electrocardiograph studies were not obtained.
30
British Journal of Anaesthesia
patients complain of nausea after operation. One patient developed a postoperative atelectasis involving the lower lobe of the left lung: owing to technical difficulties caused by kinking of the intratracheal tube, the respirations were somewhat laboured during the course of the operation, and it is probable that trichlorethylene was not to blame on this occasion. An epileptic patient with chronic bronchitis had a cough accompanied by pyrexia for a few days following operation. Apart from these two cases there were no chest complications due to trichlorethylene. Postoperative recovery was rapid, and most patients were fully conscious, within an hour from the time the operation ended. COMMENTS AND CONCLUSIONS Downloaded from http://bja.oxfordjournals.org/ at University of Arizona on July 8, 2015
Trichlorethylene provides a safe and pleasant anaesthesia for neurosurgical operations, most of which require little more than analgesia. By using the " open " T-piece technique anaesthesia is tranquil and free from vascular congestion. Possibly because air is admitted to the system and there is no accumulation of anaesthetic, cardiac irregularities are few and the rate of respiration is not unduly rapid. From reports published it is evident that most of the difficulties encountered are associated with closed methods of administration, in which the anaesthetic concentration may rise to a higher level than when an open method is employed. Trichlorethylene should be used with caution in the case of young children or patients suffering from toxaemia or heart disease. It is especially suitable for operations where a light plane of anaesthesia is required; when deep anaesthesia is necessary, cyclopropane or ether is better from every point of view. When the services of a skilled anaesthetist are available almost any neurosurgical operation (except closed head injuries) can be performed under general anaesthesia with benefit to all concerned. For minor procedures continuous intravenous Pentothal Sodium is very useful, providing care is taken to maintain a free airway. If the anaesthetist is prepared to support the patient's jaw for four hours, this method may also be used for major operations; but it is
Anaesthesia for Neurosurgery
31
doubtful whether the results are worth the trouble. In suitable cases rectal Pentothal (1 gm. per 50 lbs. body weight) forms a pleasant method of inducing anaesthesia in young children, especially for encephalograms, or " cleaning up " and suturing scalp wounds. Recently a technique has been described' in which rectal tribromethanol supplemented by intravenous Pentothal Sodium is the anaesthetic of choice for neurosurgical operations: this method has attractive possibilities but it is not stated whether difficulties are encountered in maintaining a free airway. In concluding this paper I wish to acknowledge the help and encouragement which I have received from Mr. G. F. Rowbotham, Surgeon in Charge of the Neurosurgical Department at the Newcastle-upon-Tyne General Hospital.
1. Ayre, T. P. Lancet. March 6th, 1937, p. 561. 2. Hewer, C. L. Proceedings of the Royal Society of Medicine (Anaesthetic Section), March 6th, 1942; also " Recent Advances in Anaesthesia and Analgesia," 4th edition, chapter VII. 3. Brennan, H. J. Lancet, February 5th, 1938, p. 315. 4. Culbert, T. D. Brit. Med. Journ., May 8th, 1943, p. 582. 5. Waters, R. M., O. S. Orth, and N. A. Gillespie. Anesthesiology, January 1943, Vol. IV, No. 1. 6. Gordon, R. A., and R. P. W. Shackleton. Brit. Med. Journ., March 27th, 1943, p. 380. 7. Durshordwe, Clarence J. Current Researches in Anesthesia and Analgesia, March, 1942, Vol, 21, No. 2, p. 61.
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REFERENCES