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DEATH ATTRIBUTABLE TO ANAESTHESIA
Br.J. Anaesth. (1978), 50, 1041
DEATH ATTRIBUTABLE TO ANAESTHESIA A 10-year survey (1967-1976) G. G. HARRISON SUMMARY
Although anaesthesia per se does not correct deformity, restore health or stay death, it is perhaps the most important adjunct to the care of the surgical patient, making possible activities which do accomplish these things. Of itself non-therapeutic, above all it must be safe for the patient. In no field of medical endeavour does the precept "to do no harm" have more cogency than in clinical anaesthesia. Whatever advances are claimed for anaesthesia, they can be regarded as real advances only if they result in an increase in safety for the patient. A precise measure of this safety is difficult. We postulate that the most fundamental index of the safety of anaesthesia for the patient is the frequency with which factors related to the administration of an anaesthetic cause or are contributory to a patient's death. This in itself is not something that can be estimated with scientific precision, but if we can be content with a clinical assessment of the relevant data, a useful measure of the "safety of anaesthesia" does emerge. Of importance are the clinical lessons yielded by such assessment which are essential to the improvement of the service to the patient. A prospective survey and assessment of all mortality associated with anaesthesia at Groote Schuur Hospital, Cape Town, since 1956 has been undertaken. Groote Schuur Hospital is the 1300-bedded principal teaching hospital of the University of Cape Town Medical School. The data from the past 10 years, 1967-1976 are reported here, that is the mortality associated with 240 483 anaesthetics. GAISFORD G.
HARRISON, M.D.(U.C.T.), F.F.A.R.C.S.(ENG),
Department of Anaesthetics, University of Cape Town, Cape Town, S. Africa. 0007-0912/78/0050-1041 $01.00 85
DEFINITIONS
Death associated with anaesthesia is defined as a death occurring during or within 24 h of anaesthesia or after the failure of a patient, conscious before, to regain consciousness after anaesthesia. The choice of a period of 24 h after anaesthesia is arbitrary. It embraces a period adequate to permit identification of death attributed to anaesthesia without the study becoming unmanageably large. Extension of this study to a surveillance of the whole period after operation, although desirable in some respects, would have added considerably to its difficulties and complexities. It is acknowledged that in these circumstances a very small number of deaths to which anaesthesia was a major contributory factor, such as late deaths from aspiration and pneumonia, might have been missed. For each death associated with anaesthesia, the clinical records, together with an account of the conduct of the anaesthetic, were obtained from the anaesthetist concerned. This information, together with the postmortem report, was examined in the light of three questions: (1) Was the administration of the anaesthetic or other factors within the ambit of the anaesthetist's responsibility the cause of or a major contributory factor in the patient's death? Or was the death primarily a result of the patient's disease or the surgical procedure being undertaken ? The former were classed as "deaths contributed to by anaesthesia", the latter "deaths from other causes". (2) If it was considered to be death to which anaesthesia contributed, what was the precise cause ? © Macmillan Journals Ltd 1978
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The mortality associated with 240 483 anaesthetics administered over 10 years at Groote Schuur Hospital, Cape Town, is reported. The frequency of death to which anaesthesia contributed was 0.22 per 1000 anaesthetics (compared with 0.33 per 1000 in the previous 10 years). These deaths were responsible for 2.2% of the total mortality from surgery. Two-thirds of the "anaesthetic" deaths were attributable to (in order of frequency): (a) hypovolaemia; (b) respiratory inadequacy following myoneural blockade; (c) complications of tracheal intubation; (d) inadequate postoperative care and supervision.
1042
BRITISH JOURNAL OF ANAESTHESIA
(3) Was the death preventable ? What departure was there from accepted clinical practice ? Was there a clinical lesson to be learned ?
GENERAL FREQUENCY
The general statistical data are presented in table I. For comparison relevant data from the first 10 years of this survey (1957-1966) are included in parentheses (Harrison, 1968a, b). The figure for the number of anaesthetics administered is a crude total which includes all anaesthetics administered in the hospital, from those for minor surgery to those for cardiopulmonary bypass procedures. Though this begs the future refinement of this study to an analysis of mortality associated with anaesthesia in relation to specific surgical operations, pilot studies have not shown this to be really valuable in the present context. During the period of this survey, 531 deaths
No. of
deaths Total surgical mortality Deaths associated with anaesthesia Group 1. Deaths to which anaesthesia contributed
%of AAD
2442 (2026)
10.15 (11.38)
531
2.20 (2.33)
(414)
53
10
(58) 2. Other causes
343
65
(261) 3. Inevitable deaths
Frequency per 1000 anaesthetics
135
(95)
25
0.22 (0.33) 1.42 (1.43) 0.56 (0.53)
occurred in association with anaesthesia (2.2 deaths per 1000 anaesthetics) of which 10% (53) were finally assessed as those to which anaesthesia contributed. This frequency (0.22 per 1000 anaesthetics) is an improvement on that reported from the previous 10year period surveyed at this hospital, 0.33 per 1000 anaesthetics. As anaesthesia is but an adjunct to the total surgical care of the patient, a wider relevance emerges if the frequency of those deaths to which anaesthesia contributed is viewed against the background of the total surgical mortality, that is all deaths following operation, before discharge of the patient from hospital. Looked at in this way, we may say that, in our hospital, anaesthesia and its mismanagement were responsible in a preventable manner for 2.2% of the total surgical mortality. An examination of the frequency of the deaths attributable to anaesthesia from 1956 on an annual basis (fig. 1) reveals that, following an initial improvement, the frequency decreased to what appears to be an irreducible minimum around 0.15 deaths per 1000 anaesthetics. This is perhaps a reflection of the sad fact that despite the preventability of such deaths and the repetitiveness of the errors that cause it, all trainees must be educated clinically through the same mistakes. While a constant and adequate supervision of trainees by experienced specialist staff does improve matters, it is only part of the answer, for the most enduring lessons for the trainee come ultimately from the final acceptance of total clinical responsibility.
Downloaded from http://bja.oxfordjournals.org/ at University of Michigan on April 19, 2015
With regard to question (1), besides the two groups denned, deaths to which anaesthesia contributed and deaths from other causes, there emerged a need for a third group for deaths associated with the surgery of desperation, operations on the moribund, deaths for which although an anaesthetic aetiology may not have seemed directly responsible, often it could not be excluded entirely—circumstances in which anaesthesia might be regarded as being necessarily but unavoidably contributory. Such deaths were classified as a separate group, "inevitable deaths". In assessing the contributory role of anaesthesia, harsh criteria were adopted. This was done in order to avoid any bias that might encourage complacency. The causes of deaths attributable to anaesthesia were classified in terms of the simple concept of identification of the mechanism primarily responsible for the ultimate failure of perfusion of the brain with oxygenated blood which were, fundamentally, a failure of (a) respiratory homeostasis, or (b) circulatory homeostasis. Although there may be a prominent feature in the circumstances of a particular death, from the clinical aspect the causes of deaths attributable to anaesthesia are often multiple, compounded from the interaction of many variables. This creates difficulties in terms of a precise classification, but in a study of this nature it is the aspect of preventability—the clinical lesson that may be learnt—that is important. This I have endeavoured to accentuate at the expense of some overlap and imprecision in the classification of causes of death presented.
TABLE I. Deaths associated with anaesthesia {AAV) at Groote Schuur Hospital 1967-1976 (number of anaesthetics = 240 483). Figures for 1956-1966 in parentheses {number of anaesthetics = 177 928)
DEATH ATTRIBUTABLE TO ANAESTHESIA
1043
3.0 -i
25 -
2.0 DEATHS PER 1 5 1000 ANAESTHETICS
1963 64 65 66 67 68 69 70 71 72 73 74 7b 76
FIG. 1. Anaesthetic-associated mortality 1956-1976. Clear columns = Mortality associated with anaesthesia; Solid columns = Mortality attributable to anaesthesia. TABLE II. Causes of death to which anaesthesia contributed (ACD). *Clinical situation responsible for more than two-thirds of ACD (68%) Failure of Respiratory homeostasis
Circulatory homeostasis
Complications of regional anaesthesia
Cause of death Technical failure Vomiting, regurgitation, inhalation Bronchial obstruction "Complications of tracheal intubation "Respiratory inadequacy following myoneural blockade "Inadequate postoperative care "Hypovolaemia (hypotension after induction) Overhydration Cardiac arrest Drug induced 3 Heart block 1 Air embolism 1 Uncertain 2 Spinal/extradural + haemorrhage 2 Extradural/massive spinal 1
No. of deaths 1 2 3 9 10 6 11
1.9 3.8 5.7
i
17.0 19.0 11.3 20.8 1.9
7
ISM
3
5.7 100.3
53
Status of the patient and urgency of operation Of the 53 patients to whose deaths anaesthesia was considered contributory, 27 were in good to fair condition (ASA status I and II), while 26 were in poor condition (ASA status III and IV). With regards to the urgency of operation, 32 were subject to emergency operation while 19 underwent elective procedures.
% of ACD
MECHANISMS OF DEATHS TO WHICH ANAESTHESIA CONTRIBUTED
Four clinical situations were responsible for twothirds of these deaths (table II). These were (in the order of the table): (1) Complications of tracheal intubation. (2) Respiratory inadequacy following myoneural blockade.
Downloaded from http://bja.oxfordjournals.org/ at University of Michigan on April 19, 2015
1956 57 58 59 60
1044 (3) Inadequate care and observation after operation. (4) Hypovolaemia. Complications of trachael intubation (nine patients) Over one-half of these deaths (five) followed the technical failure of endotracheal intubation in the presence of anatomical abnormality. All could have been anticipated by adequate clinical examination before anaesthesia, yet, in each instance a neuromuscular blocking drug was given by the anaesthetist before he had assured himself that he could intubate the trachea and ventilate the lungs.
Respiratory inadequacy following myoneural blockade
(10 patients) Seven of these deaths involved patients with severe chronic obstructive lung disease plus abdominal distension as a result of intestinal obstruction. The anaesthetist concerned had in each case hesitated in providing artificial ventilation in the period after operation. The deaths of another three patients were in fact a result of "over-hydration", although the patients presented as respiratory inadequacy following myoneural blockade. The patient was in each case an overweight, middle-aged female who suffered intestinal obstruction as a result of an incarcerated para-umbilical hernia, with resultant gross abdominal distension, presenting at the hospital at night. In each case fluid replacement, both before and during operation, had been over-enthusiastic, misjudged and unmonitored by measurement of central venous pressure. The resultant interstitial pulmonary oedema presented as "respiratory inadequacy following myoneural blockade" following the establishment of spontaneous breathing at the end of operation. Inadequate postoperative care (six patients)
Two further deaths from overhydration resulting in frank pulmonary oedema in the period after operation followed the inadvertent administration of excess fluid because of "inadequate postoperative care and supervision". Other deaths in this category resulted from:
(a) direct connection of an oxygen cylinder to an endotracheal tube; (b) unobserved intra-nasal disconnection of a catheter mount from a nasotracheal tube in a patient requiring ventilation; (c) inhalation in the period after operation of a massive post-turbinectomy haemorrhage in a patient who was over-sedated with morphine; (d) "Ondine's curse"—post-arousal respiratory depression following administration of morphine. Hypovolaemia (11 patients) This group might be sub-titled "post-induction hypotension" because this is how the majority presented, and it constituted the commonest single clinical situation leading to death attributable to anaesthesia. I have included under this heading all those patients in whom frank failure of circulatory homeostasis followed the induction of anaesthesia, a failure that appears to have resulted from inadequate venous return. I have chosen to call attention in this classification to the initial hypovolaemia, as this is eminently correctable. The precipitating factor was frequently the exhibition of thiopentone to the sick, old and arteriosclerotic who have evidence of ischaemic heart disease. Although some might regard many of these deaths as "drug-induced" cardiac arrest because of their direct association with thiopentone, I have chosen to highlight the functional hypovolaemic state, as often this was the basic correctable fault. Miscellaneous
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Other deaths followed the complications of kinking of the endotracheal tube (two), respiratory obstruction following herniation of the tube cuff (one) and inadvertent bronchial intubation of a patient undergoing an emergency operation while suffering from pneumonia.
BRITISH JOURNAL OF ANAESTHESIA
The remaining patients, while not constituting such homogenous groups as the above, are worthy of brief comment. Cardiac arrest (7 patients). Included in this group are: (a) Three patients in whom cardiac arrest appeared to have been directly precipitated by the anaesthetic or adjuvant drugs (other than thiopentone). Two were associated with repeat doses of suxamethonium and one followed the administration of halothane to a patient with Parkinson's disease who was being treated with L-dopa. (b) In one patient, suffering from Mobitz Type II heart block, anaesthesia and surgery precipitated complete heart block, followed by cardiac arrest on three occasions, resuscitation failing finally. This was deemed to have been preventable by the preanaesthetic insertion of temporary ventricular pacing.
DEATH ATTRIBUTABLE TO ANAESTHESIA (c) A death which resulted from "air embolism" following an attempt by the anaesthetist to expedite transfusion of blood to a patient bleeding from a gastric ulcer by the inflation of air from a sphygmomanometer cuff directly into the transfusion bottle. (d) In two further instances the cause of cardiac arrest could not be established convincingly.
TABLE III. "Inevitable deaths" Circumstances of death Cardiac surgery Ruptured abdominal aortic aneurysm Other massive haemorrhage Multiple injuries Septicaemia/peritonitis Neuro trauma Pulmonary embolus Myocardial infarction before operation Other
No. of %of deaths group 3 45 21 23 15 19 8 1 1 2
33.3 15.6 17.0 11.1 14.1
135
99.9
5.9 0.7 0.7 1.5
groups of surgical procedures and conditions were responsible for three-quarters of these deaths. These were: (a) Cardiac surgery with cardiopulmonary bypass. Deaths from failure of respiratory homeostasis (b) The surgery of major vascular catastrophes, such other than those already described included: as a ruptured abdominal aortic aneurysm. Technical failure (one patient). Incorrect assembly of a self-inflating bellows caused the anoxic death of (c) Multiple injury and other conditions associated with massive haemorrhage. patient during transfer from the operating theatre to the intensive care unit. CONCLUSION Vomiting, regurgitation and inhalation (two patients). These followed (a) Caesarean section; (b) intestinal Because of the great number of variables which influence various author's estimates of the frequency of obstruction. Bronchial obstruction (three patients). The follow- those deaths to which anaesthesia contributed— ing circumstances caused fatal bronchial obstruction differences in the peri-operative period and type of surgery, in the assessment criteria and classifications during anaesthesia: adopted and in the computation of the background (a) Blood from oesophageal varices passing an in- surgical population—no statistical comparisons sufficiently inflated endotracheal tube cuff. between surveys are valid. Comparison of this survey (b) Lack of adequate bronchial toilette of a patient has been confined to that by the same author for the anaesthetized while suffering acute purulent previous 10-year period at the same institution. There bronchitis and undergoing laparotomy for an has been improvement. Four fundamental changes ectopic pregnancy. have occurred pari passu: (c) Total bronchospasm following trachael intubation (1) A continuing improvement in routine monitoring in a patient known to have asthma. of vital functions during anaesthesia. Complications of major local anaesthetic techniques (2) An increase in the consultant (full time specialist) (three patients). Three patients died following spinal registrar (trainee) ratio, now approximating 1 : 1 . or extradural anaesthesia. In two instances major (3) A decrease in the case load per anaesthetist. bleeding during operation in the face of sympathetic paralysis as a result of the technique caused profound (4) The introduction of recovery rooms within the theatre area and adjacent intensive care units. and uncontrollable hypotension. In the remaining instance the mismanagement of total spinal anaesthesia Although the actual frequency of death attributable complicating attempted extradural block caused the to anaesthesia was small (0.22 deaths per 1000 death of the patient. anaesthetics), it is salutory to reflect that the 10% of immediate operative mortality for which anaesthesia INEVITABLE DEATHS and its mismanagement was responsible was basically "Inevitable deaths" constituted 25% of those associ- preventable. It is sad to reflect that the causes of ated with anaesthesia (see table III). Three broad anaesthetic deaths are, by and large, simple and usually
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Overhydration (one patient). Although six patients died because of "overhydration", only one is listed here, the other five having been included above under "respiratory inadequacy following myoneural blockade" and "inadequate postoperative care". This remaining death was from pulmonary oedema following inadequately monitored resuscitation of a patient, who had a previous myocardial infarction, undergoing gastrectomy for haematemesis.
1045
1046
BRITISH JOURNAL OF ANAESTHESIA
REFERENCES
Harrison, G. G. (1968a). Anaesthetic contributory death. Part I. S. Afr. Med.J., 42, 514. (1968b). Anaesthetic contributory death. Part II. 5. Afr. Med. J., 42, 544. DECES ATTRIBUABLES A L'ANESTHESIE Etude portant sur 10 ans (1967-76) RESUME
La mortalite associee a 240 483 cas d'anesthesie administree pendant 10 ans a Ph6pital de Groote Schuur a Capetown fait Pobjet de ce rapport. La frequence des dices auxquels Panesthesie a contribui a ete de 0,22%o (par rapport a 0,33%o au cours des 10 annees precSdentes). Ces deces ont compte pour 2,2% du total de la mortality resultant des interventions chirurgicales. Les deux-tiers des dices par suite d'anesthe'sie ont ete attribuables (dans Pordre de frequence): (a) a Phypovolemie; (b) a Pinsuffisance respiratoire apres blocage myoneural; (c) aux complications
resultant de Pintubation tracheale; (d) a des soins et surveillance postoperatoires inadequate. TOD DURCH ANASTHESIE Ein Vberblick auf die 10 Jahre von 1967-1976 ZUSAMMENFASSUNG
Berichtet wurde die Sterblichkeitsziffer in Verbindung mit 240 483 Narkosen, verabreicht wahrend 10 Jahren im Groote Schuur Hospital in Cape Town. Die Sterblichkeitsrate, die auf Narkose zuruckzufuhren war, war 0,22 pro 1000 Narkosen (verglichen mit 0,33 pro 1000 in den vorausgegangenen 10 Jahren). Diese Tode machten 2,2% der gesamten Sterblichkeitsziffer der Chirurgie aus. Zwei Drittel der Narkosetode waren verursacht durch (in Reihenfolge der Haufigkeit): (a) Hypovolamie; (b) Atmungsversagen nach neuromuskularer Blockade; (c) Komplikationen der trachealen Intubation; (d) unzulangliche, postoperative Pflege und Beufsichtigung. MUERTE ATRIBUIBLE A ANESTESIA Un estudio que abarcb 10 afios (1967-1976) SUMARIO
Se informa sobre la mortalidad asociada con 240 483 anestesicos administrados durante un peridodo de 10 anos en el hospital de Groote Schuur, Ciudad del Cabo. La frecuencia de muerte atribuida a anestesia fue de 0,22 por 1000 anestesias (en comparacidn con un 0,33 por 1000 en los 10 anos anteriores). Estas muertes corresponden a un 2,2% de la mortalidad total por cirugia. Dos tercios de la muertes "anestesicas" fueron imputables a (en orden de frecuencia): (a) hipovolemia; (b) insuficiencia respiratoria siguiendo un bloqueo mioneural; (c) complicaciones de intubaci6n traqueal; (d) falta de ciudado y supervisi6n postoperatorios.
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follow the lack of observation of simple precautions, and the lack of clinical alertness. What is more, in general, these causes recur. It is also sobering to reflect that these patients reported here are probably the tip of an iceberg of clinical mismanagement. How many more have nearly died ? Surveys and studies such as this are somewhat pedestrian and are tedious in the extreme to conduct, but if they are carried out consistently and conscientiously, they will provide us not only with the clinical lessons by which we can improve our practice, but also the only means by which we may measure and evaluate the safety of anaesthesia for the patient.
DEATH ATTRIBUTABLE TO ANAESTHESIA A 10-year survey (1967-1976) G. G. HARRISON SUMMARY
Although anaesthesia per se does not correct deformity, restore health or stay death, it is perhaps the most important adjunct to the care of the surgical patient, making possible activities which do accomplish these things. Of itself non-therapeutic, above all it must be safe for the patient. In no field of medical endeavour does the precept "to do no harm" have more cogency than in clinical anaesthesia. Whatever advances are claimed for anaesthesia, they can be regarded as real advances only if they result in an increase in safety for the patient. A precise measure of this safety is difficult. We postulate that the most fundamental index of the safety of anaesthesia for the patient is the frequency with which factors related to the administration of an anaesthetic cause or are contributory to a patient's death. This in itself is not something that can be estimated with scientific precision, but if we can be content with a clinical assessment of the relevant data, a useful measure of the "safety of anaesthesia" does emerge. Of importance are the clinical lessons yielded by such assessment which are essential to the improvement of the service to the patient. A prospective survey and assessment of all mortality associated with anaesthesia at Groote Schuur Hospital, Cape Town, since 1956 has been undertaken. Groote Schuur Hospital is the 1300-bedded principal teaching hospital of the University of Cape Town Medical School. The data from the past 10 years, 1967-1976 are reported here, that is the mortality associated with 240 483 anaesthetics. GAISFORD G.
HARRISON, M.D.(U.C.T.), F.F.A.R.C.S.(ENG),
Department of Anaesthetics, University of Cape Town, Cape Town, S. Africa. 0007-0912/78/0050-1041 $01.00 85
DEFINITIONS
Death associated with anaesthesia is defined as a death occurring during or within 24 h of anaesthesia or after the failure of a patient, conscious before, to regain consciousness after anaesthesia. The choice of a period of 24 h after anaesthesia is arbitrary. It embraces a period adequate to permit identification of death attributed to anaesthesia without the study becoming unmanageably large. Extension of this study to a surveillance of the whole period after operation, although desirable in some respects, would have added considerably to its difficulties and complexities. It is acknowledged that in these circumstances a very small number of deaths to which anaesthesia was a major contributory factor, such as late deaths from aspiration and pneumonia, might have been missed. For each death associated with anaesthesia, the clinical records, together with an account of the conduct of the anaesthetic, were obtained from the anaesthetist concerned. This information, together with the postmortem report, was examined in the light of three questions: (1) Was the administration of the anaesthetic or other factors within the ambit of the anaesthetist's responsibility the cause of or a major contributory factor in the patient's death? Or was the death primarily a result of the patient's disease or the surgical procedure being undertaken ? The former were classed as "deaths contributed to by anaesthesia", the latter "deaths from other causes". (2) If it was considered to be death to which anaesthesia contributed, what was the precise cause ? © Macmillan Journals Ltd 1978
Downloaded from http://bja.oxfordjournals.org/ at University of Michigan on April 19, 2015
The mortality associated with 240 483 anaesthetics administered over 10 years at Groote Schuur Hospital, Cape Town, is reported. The frequency of death to which anaesthesia contributed was 0.22 per 1000 anaesthetics (compared with 0.33 per 1000 in the previous 10 years). These deaths were responsible for 2.2% of the total mortality from surgery. Two-thirds of the "anaesthetic" deaths were attributable to (in order of frequency): (a) hypovolaemia; (b) respiratory inadequacy following myoneural blockade; (c) complications of tracheal intubation; (d) inadequate postoperative care and supervision.
1042
BRITISH JOURNAL OF ANAESTHESIA
(3) Was the death preventable ? What departure was there from accepted clinical practice ? Was there a clinical lesson to be learned ?
GENERAL FREQUENCY
The general statistical data are presented in table I. For comparison relevant data from the first 10 years of this survey (1957-1966) are included in parentheses (Harrison, 1968a, b). The figure for the number of anaesthetics administered is a crude total which includes all anaesthetics administered in the hospital, from those for minor surgery to those for cardiopulmonary bypass procedures. Though this begs the future refinement of this study to an analysis of mortality associated with anaesthesia in relation to specific surgical operations, pilot studies have not shown this to be really valuable in the present context. During the period of this survey, 531 deaths
No. of
deaths Total surgical mortality Deaths associated with anaesthesia Group 1. Deaths to which anaesthesia contributed
%of AAD
2442 (2026)
10.15 (11.38)
531
2.20 (2.33)
(414)
53
10
(58) 2. Other causes
343
65
(261) 3. Inevitable deaths
Frequency per 1000 anaesthetics
135
(95)
25
0.22 (0.33) 1.42 (1.43) 0.56 (0.53)
occurred in association with anaesthesia (2.2 deaths per 1000 anaesthetics) of which 10% (53) were finally assessed as those to which anaesthesia contributed. This frequency (0.22 per 1000 anaesthetics) is an improvement on that reported from the previous 10year period surveyed at this hospital, 0.33 per 1000 anaesthetics. As anaesthesia is but an adjunct to the total surgical care of the patient, a wider relevance emerges if the frequency of those deaths to which anaesthesia contributed is viewed against the background of the total surgical mortality, that is all deaths following operation, before discharge of the patient from hospital. Looked at in this way, we may say that, in our hospital, anaesthesia and its mismanagement were responsible in a preventable manner for 2.2% of the total surgical mortality. An examination of the frequency of the deaths attributable to anaesthesia from 1956 on an annual basis (fig. 1) reveals that, following an initial improvement, the frequency decreased to what appears to be an irreducible minimum around 0.15 deaths per 1000 anaesthetics. This is perhaps a reflection of the sad fact that despite the preventability of such deaths and the repetitiveness of the errors that cause it, all trainees must be educated clinically through the same mistakes. While a constant and adequate supervision of trainees by experienced specialist staff does improve matters, it is only part of the answer, for the most enduring lessons for the trainee come ultimately from the final acceptance of total clinical responsibility.
Downloaded from http://bja.oxfordjournals.org/ at University of Michigan on April 19, 2015
With regard to question (1), besides the two groups denned, deaths to which anaesthesia contributed and deaths from other causes, there emerged a need for a third group for deaths associated with the surgery of desperation, operations on the moribund, deaths for which although an anaesthetic aetiology may not have seemed directly responsible, often it could not be excluded entirely—circumstances in which anaesthesia might be regarded as being necessarily but unavoidably contributory. Such deaths were classified as a separate group, "inevitable deaths". In assessing the contributory role of anaesthesia, harsh criteria were adopted. This was done in order to avoid any bias that might encourage complacency. The causes of deaths attributable to anaesthesia were classified in terms of the simple concept of identification of the mechanism primarily responsible for the ultimate failure of perfusion of the brain with oxygenated blood which were, fundamentally, a failure of (a) respiratory homeostasis, or (b) circulatory homeostasis. Although there may be a prominent feature in the circumstances of a particular death, from the clinical aspect the causes of deaths attributable to anaesthesia are often multiple, compounded from the interaction of many variables. This creates difficulties in terms of a precise classification, but in a study of this nature it is the aspect of preventability—the clinical lesson that may be learnt—that is important. This I have endeavoured to accentuate at the expense of some overlap and imprecision in the classification of causes of death presented.
TABLE I. Deaths associated with anaesthesia {AAV) at Groote Schuur Hospital 1967-1976 (number of anaesthetics = 240 483). Figures for 1956-1966 in parentheses {number of anaesthetics = 177 928)
DEATH ATTRIBUTABLE TO ANAESTHESIA
1043
3.0 -i
25 -
2.0 DEATHS PER 1 5 1000 ANAESTHETICS
1963 64 65 66 67 68 69 70 71 72 73 74 7b 76
FIG. 1. Anaesthetic-associated mortality 1956-1976. Clear columns = Mortality associated with anaesthesia; Solid columns = Mortality attributable to anaesthesia. TABLE II. Causes of death to which anaesthesia contributed (ACD). *Clinical situation responsible for more than two-thirds of ACD (68%) Failure of Respiratory homeostasis
Circulatory homeostasis
Complications of regional anaesthesia
Cause of death Technical failure Vomiting, regurgitation, inhalation Bronchial obstruction "Complications of tracheal intubation "Respiratory inadequacy following myoneural blockade "Inadequate postoperative care "Hypovolaemia (hypotension after induction) Overhydration Cardiac arrest Drug induced 3 Heart block 1 Air embolism 1 Uncertain 2 Spinal/extradural + haemorrhage 2 Extradural/massive spinal 1
No. of deaths 1 2 3 9 10 6 11
1.9 3.8 5.7
i
17.0 19.0 11.3 20.8 1.9
7
ISM
3
5.7 100.3
53
Status of the patient and urgency of operation Of the 53 patients to whose deaths anaesthesia was considered contributory, 27 were in good to fair condition (ASA status I and II), while 26 were in poor condition (ASA status III and IV). With regards to the urgency of operation, 32 were subject to emergency operation while 19 underwent elective procedures.
% of ACD
MECHANISMS OF DEATHS TO WHICH ANAESTHESIA CONTRIBUTED
Four clinical situations were responsible for twothirds of these deaths (table II). These were (in the order of the table): (1) Complications of tracheal intubation. (2) Respiratory inadequacy following myoneural blockade.
Downloaded from http://bja.oxfordjournals.org/ at University of Michigan on April 19, 2015
1956 57 58 59 60
1044 (3) Inadequate care and observation after operation. (4) Hypovolaemia. Complications of trachael intubation (nine patients) Over one-half of these deaths (five) followed the technical failure of endotracheal intubation in the presence of anatomical abnormality. All could have been anticipated by adequate clinical examination before anaesthesia, yet, in each instance a neuromuscular blocking drug was given by the anaesthetist before he had assured himself that he could intubate the trachea and ventilate the lungs.
Respiratory inadequacy following myoneural blockade
(10 patients) Seven of these deaths involved patients with severe chronic obstructive lung disease plus abdominal distension as a result of intestinal obstruction. The anaesthetist concerned had in each case hesitated in providing artificial ventilation in the period after operation. The deaths of another three patients were in fact a result of "over-hydration", although the patients presented as respiratory inadequacy following myoneural blockade. The patient was in each case an overweight, middle-aged female who suffered intestinal obstruction as a result of an incarcerated para-umbilical hernia, with resultant gross abdominal distension, presenting at the hospital at night. In each case fluid replacement, both before and during operation, had been over-enthusiastic, misjudged and unmonitored by measurement of central venous pressure. The resultant interstitial pulmonary oedema presented as "respiratory inadequacy following myoneural blockade" following the establishment of spontaneous breathing at the end of operation. Inadequate postoperative care (six patients)
Two further deaths from overhydration resulting in frank pulmonary oedema in the period after operation followed the inadvertent administration of excess fluid because of "inadequate postoperative care and supervision". Other deaths in this category resulted from:
(a) direct connection of an oxygen cylinder to an endotracheal tube; (b) unobserved intra-nasal disconnection of a catheter mount from a nasotracheal tube in a patient requiring ventilation; (c) inhalation in the period after operation of a massive post-turbinectomy haemorrhage in a patient who was over-sedated with morphine; (d) "Ondine's curse"—post-arousal respiratory depression following administration of morphine. Hypovolaemia (11 patients) This group might be sub-titled "post-induction hypotension" because this is how the majority presented, and it constituted the commonest single clinical situation leading to death attributable to anaesthesia. I have included under this heading all those patients in whom frank failure of circulatory homeostasis followed the induction of anaesthesia, a failure that appears to have resulted from inadequate venous return. I have chosen to call attention in this classification to the initial hypovolaemia, as this is eminently correctable. The precipitating factor was frequently the exhibition of thiopentone to the sick, old and arteriosclerotic who have evidence of ischaemic heart disease. Although some might regard many of these deaths as "drug-induced" cardiac arrest because of their direct association with thiopentone, I have chosen to highlight the functional hypovolaemic state, as often this was the basic correctable fault. Miscellaneous
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Other deaths followed the complications of kinking of the endotracheal tube (two), respiratory obstruction following herniation of the tube cuff (one) and inadvertent bronchial intubation of a patient undergoing an emergency operation while suffering from pneumonia.
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The remaining patients, while not constituting such homogenous groups as the above, are worthy of brief comment. Cardiac arrest (7 patients). Included in this group are: (a) Three patients in whom cardiac arrest appeared to have been directly precipitated by the anaesthetic or adjuvant drugs (other than thiopentone). Two were associated with repeat doses of suxamethonium and one followed the administration of halothane to a patient with Parkinson's disease who was being treated with L-dopa. (b) In one patient, suffering from Mobitz Type II heart block, anaesthesia and surgery precipitated complete heart block, followed by cardiac arrest on three occasions, resuscitation failing finally. This was deemed to have been preventable by the preanaesthetic insertion of temporary ventricular pacing.
DEATH ATTRIBUTABLE TO ANAESTHESIA (c) A death which resulted from "air embolism" following an attempt by the anaesthetist to expedite transfusion of blood to a patient bleeding from a gastric ulcer by the inflation of air from a sphygmomanometer cuff directly into the transfusion bottle. (d) In two further instances the cause of cardiac arrest could not be established convincingly.
TABLE III. "Inevitable deaths" Circumstances of death Cardiac surgery Ruptured abdominal aortic aneurysm Other massive haemorrhage Multiple injuries Septicaemia/peritonitis Neuro trauma Pulmonary embolus Myocardial infarction before operation Other
No. of %of deaths group 3 45 21 23 15 19 8 1 1 2
33.3 15.6 17.0 11.1 14.1
135
99.9
5.9 0.7 0.7 1.5
groups of surgical procedures and conditions were responsible for three-quarters of these deaths. These were: (a) Cardiac surgery with cardiopulmonary bypass. Deaths from failure of respiratory homeostasis (b) The surgery of major vascular catastrophes, such other than those already described included: as a ruptured abdominal aortic aneurysm. Technical failure (one patient). Incorrect assembly of a self-inflating bellows caused the anoxic death of (c) Multiple injury and other conditions associated with massive haemorrhage. patient during transfer from the operating theatre to the intensive care unit. CONCLUSION Vomiting, regurgitation and inhalation (two patients). These followed (a) Caesarean section; (b) intestinal Because of the great number of variables which influence various author's estimates of the frequency of obstruction. Bronchial obstruction (three patients). The follow- those deaths to which anaesthesia contributed— ing circumstances caused fatal bronchial obstruction differences in the peri-operative period and type of surgery, in the assessment criteria and classifications during anaesthesia: adopted and in the computation of the background (a) Blood from oesophageal varices passing an in- surgical population—no statistical comparisons sufficiently inflated endotracheal tube cuff. between surveys are valid. Comparison of this survey (b) Lack of adequate bronchial toilette of a patient has been confined to that by the same author for the anaesthetized while suffering acute purulent previous 10-year period at the same institution. There bronchitis and undergoing laparotomy for an has been improvement. Four fundamental changes ectopic pregnancy. have occurred pari passu: (c) Total bronchospasm following trachael intubation (1) A continuing improvement in routine monitoring in a patient known to have asthma. of vital functions during anaesthesia. Complications of major local anaesthetic techniques (2) An increase in the consultant (full time specialist) (three patients). Three patients died following spinal registrar (trainee) ratio, now approximating 1 : 1 . or extradural anaesthesia. In two instances major (3) A decrease in the case load per anaesthetist. bleeding during operation in the face of sympathetic paralysis as a result of the technique caused profound (4) The introduction of recovery rooms within the theatre area and adjacent intensive care units. and uncontrollable hypotension. In the remaining instance the mismanagement of total spinal anaesthesia Although the actual frequency of death attributable complicating attempted extradural block caused the to anaesthesia was small (0.22 deaths per 1000 death of the patient. anaesthetics), it is salutory to reflect that the 10% of immediate operative mortality for which anaesthesia INEVITABLE DEATHS and its mismanagement was responsible was basically "Inevitable deaths" constituted 25% of those associ- preventable. It is sad to reflect that the causes of ated with anaesthesia (see table III). Three broad anaesthetic deaths are, by and large, simple and usually
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Overhydration (one patient). Although six patients died because of "overhydration", only one is listed here, the other five having been included above under "respiratory inadequacy following myoneural blockade" and "inadequate postoperative care". This remaining death was from pulmonary oedema following inadequately monitored resuscitation of a patient, who had a previous myocardial infarction, undergoing gastrectomy for haematemesis.
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REFERENCES
Harrison, G. G. (1968a). Anaesthetic contributory death. Part I. S. Afr. Med.J., 42, 514. (1968b). Anaesthetic contributory death. Part II. 5. Afr. Med. J., 42, 544. DECES ATTRIBUABLES A L'ANESTHESIE Etude portant sur 10 ans (1967-76) RESUME
La mortalite associee a 240 483 cas d'anesthesie administree pendant 10 ans a Ph6pital de Groote Schuur a Capetown fait Pobjet de ce rapport. La frequence des dices auxquels Panesthesie a contribui a ete de 0,22%o (par rapport a 0,33%o au cours des 10 annees precSdentes). Ces deces ont compte pour 2,2% du total de la mortality resultant des interventions chirurgicales. Les deux-tiers des dices par suite d'anesthe'sie ont ete attribuables (dans Pordre de frequence): (a) a Phypovolemie; (b) a Pinsuffisance respiratoire apres blocage myoneural; (c) aux complications
resultant de Pintubation tracheale; (d) a des soins et surveillance postoperatoires inadequate. TOD DURCH ANASTHESIE Ein Vberblick auf die 10 Jahre von 1967-1976 ZUSAMMENFASSUNG
Berichtet wurde die Sterblichkeitsziffer in Verbindung mit 240 483 Narkosen, verabreicht wahrend 10 Jahren im Groote Schuur Hospital in Cape Town. Die Sterblichkeitsrate, die auf Narkose zuruckzufuhren war, war 0,22 pro 1000 Narkosen (verglichen mit 0,33 pro 1000 in den vorausgegangenen 10 Jahren). Diese Tode machten 2,2% der gesamten Sterblichkeitsziffer der Chirurgie aus. Zwei Drittel der Narkosetode waren verursacht durch (in Reihenfolge der Haufigkeit): (a) Hypovolamie; (b) Atmungsversagen nach neuromuskularer Blockade; (c) Komplikationen der trachealen Intubation; (d) unzulangliche, postoperative Pflege und Beufsichtigung. MUERTE ATRIBUIBLE A ANESTESIA Un estudio que abarcb 10 afios (1967-1976) SUMARIO
Se informa sobre la mortalidad asociada con 240 483 anestesicos administrados durante un peridodo de 10 anos en el hospital de Groote Schuur, Ciudad del Cabo. La frecuencia de muerte atribuida a anestesia fue de 0,22 por 1000 anestesias (en comparacidn con un 0,33 por 1000 en los 10 anos anteriores). Estas muertes corresponden a un 2,2% de la mortalidad total por cirugia. Dos tercios de la muertes "anestesicas" fueron imputables a (en orden de frecuencia): (a) hipovolemia; (b) insuficiencia respiratoria siguiendo un bloqueo mioneural; (c) complicaciones de intubaci6n traqueal; (d) falta de ciudado y supervisi6n postoperatorios.
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follow the lack of observation of simple precautions, and the lack of clinical alertness. What is more, in general, these causes recur. It is also sobering to reflect that these patients reported here are probably the tip of an iceberg of clinical mismanagement. How many more have nearly died ? Surveys and studies such as this are somewhat pedestrian and are tedious in the extreme to conduct, but if they are carried out consistently and conscientiously, they will provide us not only with the clinical lessons by which we can improve our practice, but also the only means by which we may measure and evaluate the safety of anaesthesia for the patient.