- Email: [email protected]
Hypotensive an˦sthesia in plastic surgery
HYPOTENSIVE ANZESTHESIA IN PLASTIC SURGERY 1 By G. E. HALE ENDERBY,F.F.A.R.C.S., D.A.(Eng.) The Queen Victoria Hospital, East Grinstead IT is ten years since hypotensive anmsthesia was started at East Grinstead, and during this time a series of 5,4o7 hypotcnsivc anresthetics has been completed out of a total during the same period of 3o,95 o operations. It had been my intention originally to present straightforward figures for a mortality rate in the hypotensive and non-hypotensive series, but for reasons which will become clear later this is impossible. I want instead to spend the time at my disposal in a critical examination of the deaths which have occurred with hypotension. TABLE
Mortality ( T o t a l 7 i n 5 , 4 o 7 h y p o t e n s i v e anmsthetics)
i Cause of D e a t h .
T i m e of Occurrence.
T i m e of Death.
days after operation During operation
Operation.
Facial plastic
Sex.
F.
I. Inadequate ventilation
D u r i n g operation
2. A i r e m b o l i s m
Resection m a n d i b l e , M. tongue and block dissection glands F. During operation D u r i n g operation PIastic reconstruction of ear M. Four hours after F o u r h o u r s after Excision m a n d i b l e operation Block dissection operation glands neck J~/]. Half hour after Four days after Facial plastic operation operation Twenty hours Block d i s s e c t i o n ' F. Twenty hours after operation glands neck after operation Five days after Excision mandible I F, operation
3. A d r e n a l insufficiency 4. Spontaneous ~neumothorax 5. Acute Respiratory obstruction
6. Cardiac collapse 7. Mental disturbance ~ . P u r u l e n t bronchiolitis f
During operation
Thirteen
AL 4o 8r 27 63 63
There were twenty deaths in association with these 30,950 operations, and this implies that death occurred at or after operation and that it was caused by the anaesthesia, the surgery, or both. There were seven deaths in association with the 5,407 hypotensive anaesthetics (see table). The details of these deaths are as follows: three fatalities followed cardiac arrest on the operation table. In one of them this was caused by inadequate ventilation due to severe respiratory depression following thiolSentone. Cardiac massage restored the heart's action but the patient did not make a full recovery and died after thirteen days. Of the other two, one died from air embolism via the jugular veins, and the other from adrenal insufficiency. On theoretical grounds air embolism is more likely to occur when the neck veins are collapsed and empty and elevated above heart level as in the reversed Trendelenburg position and therefore the hypotensive technique may have contributed to this fatality, but it must be remembered that air embolism is a well-known complication of neck surgery performed with or without 1 Read at the A n n u a l M e e t i n g of the British Association o f Plastic Surgeons at East G r i n s t e a d , July 196o. 41
42
BRITISH
JOURNAL
OF
PLASTIC
SURGERY
hypotension. In the second case the use of a short-acting hypotensive agent induced a very moderate fall of pressure at the outset of the operation and it might in some way have contributed to the fatal outcome, but it is difficult to consider that it was an important contributory factor in this patient. The remaining four deaths occurred between four hours and thirteen days after operation. In two of them this was due to respiratory obstruction, one caused by a spontaneous pneumothorax and the other to airway difficulties in a black man half an hour after the operation had finished. The latter patient was resuscitated by cardiac massage but did not make a full recovery and died four days later. The third patient collapsed and died twenty hours after operation for block dissection of the glands of the neck for carcinoma. There is no ciear indication from the records that inadequate ventilation, which can easily occur after this operation, played a decisive part in this fatal result, but only that there was " cardiac collapse " in an old patient with malignant disease. The last fatality occurred five days after operation in a fat woman of 6 3 who was stone deaf. She underwent an extensive resection of the mandible for carcinoma, and the bloodpressure was not accurately controlled. An exact measurement of the pressure was not made because this occurred before the introduction of the oscillometer without which accurate control is impossible. Her recovery from anmsthesia was apparently satisfactory and indeed she was discharged from the recovery ward the following day, but back in her own ward she was non-co-operative and did not appear to understand what was happening although this was difficult to assess because of her deafness. It is conceivable that her condition was caused by an acute mental disturbance precipitated by operation or hypotension or both, and when she died five days later from purulent bronchiolitis no natural disease was found at post-mortem examination to explain her mental condition. There is therefore some doubt as to the exact cause of this fatality. D i s c u s s i o n . m F r o m all these results it is apparent that death occurred three times because of inadequate ventilation (Nos. I, 4, and 5) in association with hypotensive drugs and surgery and in a fourth patient (No. 6) it cannot be excluded with certainty. These resuks emphasise again what has been stated before, that the myocardium will not tolerate anoxia associated with hypotension. It is also important to realise that residual ganglion paralysis after long-acting hypotensive drugs diminishes the capacity of the patient to withstand such insults as respiratory obstruction or depression. In the absence of such drugs a patient can often pull through these adverse conditions, but a fatal outcome is very likely when the ganglia are paralysed. It is therefore chastening to realise that of these seven deaths, two were certainly avoidable (Nos. I and 5) by the basic principles of good amesthesia in the maintenance of a clear airway and full oxygenation. It is doubtful whether the hypotensive technique was in any way responsible for the one death which occurred twenty hours after operation for block dissection of the glands of the neck (No. 6), whilst the patient with fatal air embolism (No. 2) died for a reason quite outside the control of the ana:sthetist and one which may occur any time during an operation in the region of the great veins of the neck. The one unexplained death (No. 7) must be considered a likely complication of the hypotensive technique, particularly as the blood-pressure was not carefully controlled. This complication has not occurred in any other patient in this large series.
HYPOTENSIVE
AN/~STHESIA
IN
PLASTIC
SURGERY
43
These figures give a mortality rate of one in 800 and it is tempting to compare xhis with the overall mortality rate which as already stated was twenty in 3o,95o ,operations. But a detailed examination of these records shows that death occurred from such a wide variety of causes that any attempt at comparison or statistics is quite worthless. Thus, for instance, this series includes death from coronary -thrombosis twenty-four hours after operation and from the severe intoxication of burns three days after grafting, as well as death in the theatre from pulmonary ~embolism and an obvious anmsthetic accident. It is of no value whatever to lump all these together in order to give a neat figure for a mortality rate, for this has no :meaning. It is of greater value to analyse these results individually to find out where the error in technique or the lack of knowledge occurred. On!y one comparison Js possible. Inadequate ventilation was responsible for so many of the fatalities with hypotension, but it did not figure prominently as a cause of death in the series without hypotension. What conclusions can be drawn from this large series ? How safe is ~hypotension and how justified are we in adding ganglion paralysis to unconscious:hess ? The early mistakes which were responsible for one death (respiratory depression) (No. I) should no longer occur, and indeed it is fair to observe that the :increased skill and knowledge of the trained anmsthetist are now capable of giving adequate hypotensive operating conditions with safety. Cardiac arrest during operation has not recurred since the early days but for this we must thank the :increased care and skill devoted to an exact knowledge of blood-pressure and anmsthesia. Without this the risk of cardiac arrest is considerably greater with ~hypotensive drugs. These figures point out that such care and skill must be carried on in the immediate post-operative period, and makes the provision of skilled :nursing a necessity during recovery. The advantages of hypotension cannot be ignored in trying to assess justification for a technique with known dangers. From these results, however, it is fair to state that so many of these dangers are now clearly understood, and :indeed that the study of hypotensive anmsthesia has greatly enriched our knowledge of the mechanisms leading to sudden collapse and cardiac failure. The cause of death and the circumstances leading up to it are clearly understood in six of these 'seven deaths associated with hypotensive drugs. It is fair to state, therefore, that they are in large part avoidable, but whereas the skill of the anmsthetist may be capable of this, it must be remembered that others are involved in the care of these patients and the level of skill throughout the surgical and nursing team may not be adequate to cope with every eventuality. But it must be remembered, too, that where knowledge exists, skill will follow, particularly when that skill is ,obtained by careful and exact training.
Mortality ( T o t a l 7 i n 5 , 4 o 7 h y p o t e n s i v e anmsthetics)
i Cause of D e a t h .
T i m e of Occurrence.
T i m e of Death.
days after operation During operation
Operation.
Facial plastic
Sex.
F.
I. Inadequate ventilation
D u r i n g operation
2. A i r e m b o l i s m
Resection m a n d i b l e , M. tongue and block dissection glands F. During operation D u r i n g operation PIastic reconstruction of ear M. Four hours after F o u r h o u r s after Excision m a n d i b l e operation Block dissection operation glands neck J~/]. Half hour after Four days after Facial plastic operation operation Twenty hours Block d i s s e c t i o n ' F. Twenty hours after operation glands neck after operation Five days after Excision mandible I F, operation
3. A d r e n a l insufficiency 4. Spontaneous ~neumothorax 5. Acute Respiratory obstruction
6. Cardiac collapse 7. Mental disturbance ~ . P u r u l e n t bronchiolitis f
During operation
Thirteen
AL 4o 8r 27 63 63
There were twenty deaths in association with these 30,950 operations, and this implies that death occurred at or after operation and that it was caused by the anaesthesia, the surgery, or both. There were seven deaths in association with the 5,407 hypotensive anaesthetics (see table). The details of these deaths are as follows: three fatalities followed cardiac arrest on the operation table. In one of them this was caused by inadequate ventilation due to severe respiratory depression following thiolSentone. Cardiac massage restored the heart's action but the patient did not make a full recovery and died after thirteen days. Of the other two, one died from air embolism via the jugular veins, and the other from adrenal insufficiency. On theoretical grounds air embolism is more likely to occur when the neck veins are collapsed and empty and elevated above heart level as in the reversed Trendelenburg position and therefore the hypotensive technique may have contributed to this fatality, but it must be remembered that air embolism is a well-known complication of neck surgery performed with or without 1 Read at the A n n u a l M e e t i n g of the British Association o f Plastic Surgeons at East G r i n s t e a d , July 196o. 41
42
BRITISH
JOURNAL
OF
PLASTIC
SURGERY
hypotension. In the second case the use of a short-acting hypotensive agent induced a very moderate fall of pressure at the outset of the operation and it might in some way have contributed to the fatal outcome, but it is difficult to consider that it was an important contributory factor in this patient. The remaining four deaths occurred between four hours and thirteen days after operation. In two of them this was due to respiratory obstruction, one caused by a spontaneous pneumothorax and the other to airway difficulties in a black man half an hour after the operation had finished. The latter patient was resuscitated by cardiac massage but did not make a full recovery and died four days later. The third patient collapsed and died twenty hours after operation for block dissection of the glands of the neck for carcinoma. There is no ciear indication from the records that inadequate ventilation, which can easily occur after this operation, played a decisive part in this fatal result, but only that there was " cardiac collapse " in an old patient with malignant disease. The last fatality occurred five days after operation in a fat woman of 6 3 who was stone deaf. She underwent an extensive resection of the mandible for carcinoma, and the bloodpressure was not accurately controlled. An exact measurement of the pressure was not made because this occurred before the introduction of the oscillometer without which accurate control is impossible. Her recovery from anmsthesia was apparently satisfactory and indeed she was discharged from the recovery ward the following day, but back in her own ward she was non-co-operative and did not appear to understand what was happening although this was difficult to assess because of her deafness. It is conceivable that her condition was caused by an acute mental disturbance precipitated by operation or hypotension or both, and when she died five days later from purulent bronchiolitis no natural disease was found at post-mortem examination to explain her mental condition. There is therefore some doubt as to the exact cause of this fatality. D i s c u s s i o n . m F r o m all these results it is apparent that death occurred three times because of inadequate ventilation (Nos. I, 4, and 5) in association with hypotensive drugs and surgery and in a fourth patient (No. 6) it cannot be excluded with certainty. These resuks emphasise again what has been stated before, that the myocardium will not tolerate anoxia associated with hypotension. It is also important to realise that residual ganglion paralysis after long-acting hypotensive drugs diminishes the capacity of the patient to withstand such insults as respiratory obstruction or depression. In the absence of such drugs a patient can often pull through these adverse conditions, but a fatal outcome is very likely when the ganglia are paralysed. It is therefore chastening to realise that of these seven deaths, two were certainly avoidable (Nos. I and 5) by the basic principles of good amesthesia in the maintenance of a clear airway and full oxygenation. It is doubtful whether the hypotensive technique was in any way responsible for the one death which occurred twenty hours after operation for block dissection of the glands of the neck (No. 6), whilst the patient with fatal air embolism (No. 2) died for a reason quite outside the control of the ana:sthetist and one which may occur any time during an operation in the region of the great veins of the neck. The one unexplained death (No. 7) must be considered a likely complication of the hypotensive technique, particularly as the blood-pressure was not carefully controlled. This complication has not occurred in any other patient in this large series.
HYPOTENSIVE
AN/~STHESIA
IN
PLASTIC
SURGERY
43
These figures give a mortality rate of one in 800 and it is tempting to compare xhis with the overall mortality rate which as already stated was twenty in 3o,95o ,operations. But a detailed examination of these records shows that death occurred from such a wide variety of causes that any attempt at comparison or statistics is quite worthless. Thus, for instance, this series includes death from coronary -thrombosis twenty-four hours after operation and from the severe intoxication of burns three days after grafting, as well as death in the theatre from pulmonary ~embolism and an obvious anmsthetic accident. It is of no value whatever to lump all these together in order to give a neat figure for a mortality rate, for this has no :meaning. It is of greater value to analyse these results individually to find out where the error in technique or the lack of knowledge occurred. On!y one comparison Js possible. Inadequate ventilation was responsible for so many of the fatalities with hypotension, but it did not figure prominently as a cause of death in the series without hypotension. What conclusions can be drawn from this large series ? How safe is ~hypotension and how justified are we in adding ganglion paralysis to unconscious:hess ? The early mistakes which were responsible for one death (respiratory depression) (No. I) should no longer occur, and indeed it is fair to observe that the :increased skill and knowledge of the trained anmsthetist are now capable of giving adequate hypotensive operating conditions with safety. Cardiac arrest during operation has not recurred since the early days but for this we must thank the :increased care and skill devoted to an exact knowledge of blood-pressure and anmsthesia. Without this the risk of cardiac arrest is considerably greater with ~hypotensive drugs. These figures point out that such care and skill must be carried on in the immediate post-operative period, and makes the provision of skilled :nursing a necessity during recovery. The advantages of hypotension cannot be ignored in trying to assess justification for a technique with known dangers. From these results, however, it is fair to state that so many of these dangers are now clearly understood, and :indeed that the study of hypotensive anmsthesia has greatly enriched our knowledge of the mechanisms leading to sudden collapse and cardiac failure. The cause of death and the circumstances leading up to it are clearly understood in six of these 'seven deaths associated with hypotensive drugs. It is fair to state, therefore, that they are in large part avoidable, but whereas the skill of the anmsthetist may be capable of this, it must be remembered that others are involved in the care of these patients and the level of skill throughout the surgical and nursing team may not be adequate to cope with every eventuality. But it must be remembered, too, that where knowledge exists, skill will follow, particularly when that skill is ,obtained by careful and exact training.