J. E. Utting

Human misadventure in anaesthesia

SummaryAn account is given of the 602 anaesthetic accidents reported to the Medical Defence Union of the United Kingdom over the eight-year period 1970-1977: these were reported from a total membership of 2,000 anaesthetists. It is known that reporting of minor accidents, for example damage to teeth, is very imcomplete, and that many deaths associated with surgery but due to disease processes rather than anaesthesia would not be reported either. It is thought, however, that the reporting by members of other accidents involving death and cerebral damage is likely to be complete, or nearly so.Cases of death and cerebral damage reported numbered 348 (60 per cent of the total) and the causes of these two major accidents were so closely similar that it was possible to deal with them together. This appears to be a suitable approach since cerebral damage can be as great, or greater, a catastrophe than death. In nearly half of this group of accidents there was discernibly faulty technique. Failure of postoperative care ( 10 per cent of the 348 cases) was another prominent and avoidable cause.Analysis of the faulty anaesthetic techniques which led to these major accidents showed that factors involved in tracheal intubation were preeminent, and that misuse of apparatus was also conspicuous. Over all error was deemed to be twice as common a cause of death and cerebral damage as was misadventure.RésuméEntre 1970 et 1977, 602 accidents anesthésiques ont été rapportés au Medical Defense Union qui représente environ 87,000 médecins et dentistes (dont 2,000 anesthésistes) dans les cas de poursuites liées à la pratique de leur profession.Il est clair que ce total ne représente pas la totalité des accidents survenus. En effet, beaucoup ďaccidents mineurs, comme les traumatismes dentaires, ne sont probablement pas rapportés. De même, on ne rapporte généralement pas les décçs clairement liés à une pathologie pré-existante. Par ailleurs, il apparaït probable que la presque totalité des accidents suivis de décçs ou de dommages cérébraux sont effectivement rapportés.De tels accidents (suivis de décçs ou de dommages cérébraux) représentaient 60 pour cent du total, soit 318 cas sur 602. Les causes de ces deux types ďaccidents étaient si semblables que ľon a choisi de les considérer dans un même ensemble. Cette approche apparaït justifiée lorsque ľon considçre qu’un cas de dommage cérébral peut être aussi catastrophique qu’un décçs.Dans près de la moitié de ces accidents graves, on a pu mettre en évidence une faute technique (tube trachéal dans ľœsophage ou incapacité ďintuber et de ventiler un malade obstrué aprçs ľavoir endormi et cu rari sé, aspiration de contenu gastrique, respirateur ou tubes ďappareil ďanesthésie débranchés, cylindres ďoxygçne épuisés, usage du protoxyde ďazote alors que ľon croyait utiliser ľoxygçne, etc). Dix pour cent des cas sont survenus en phase post-opératoire (surtout des problçmes ďobstruction des voies aériennes. Par comparaison aux situations peu prévisibles (hyperthermic maligne, hépatites à ľhalothane) reliées à la pathologie préexistante, ľerreur humaine était en cause dans une proportion de deux pour un.

A comparison of the induction characteristics of thiopentone and propofol (2, 6‐di‐isopropyl phenol)

A study has been undertaken to compare the induction characteristics of the new intravenous anaesthetic agent 2,6 di‐isopropyl phenol, newly prepared in a lipid emulsion (propofol) with those of thiopentone. Despite a significantly higher incidence of pain on injection and spontaneous movement, the new agent was felt to perform comparably to thiopentone as an induction agent. Unfortunately, propofol caused decreases in blood pressure which were significantly greater than those seen after thiopentone. This feature may prove to be a considerable hurdle to the general acceptance of propofol.

Vecuronium in the myasthenic patient

The use of vecuronium in six patients with myasthenia gravis undergoing thymectomy is described; the train‐of‐four twitch technique was used to monitor neuromuscular function. The first two patients received an initial dose of 0.02 mg/kg and incremental doses of 4 μg/kg, which is in the order of one fifth of that normally used. Satisfactory depression of the first twitch of the train‐of‐four, however, was not obtained and, therefore, in the remaining four patients the doses were doubled. At this dose satisfactory depression of the first twitch was achieved. Neostigmine 5.0 mg produced adequate reversal of residual neuromuscular blockade and the train‐of‐four twitch response recovered to normal levels. With reduced dosage and with careful neuromuscular monitoring. vecuronium can be used safely in the myasthenic patient.

Atracurium in the myasthenic patient

The use of the new competitive muscle relaxant, atracurium, is described in five myasthenic patients presenting for thymectomy. With an initial dose of 0.1 mg/kg, that is approximately one‐fifth of that normally used, and incremental doses of 0.02–0.04 mg/kg, satisfactory clinical conditions were achieved. Neuromuscular function was monitored throughout using the train‐of‐four mechanical twitch response, and residual neuromuscular blockade was reversed satisfactorily at the end of the procedure with neo‐stigmine 5.0 mg. A marked increase in the magnitude of the first twitch of the train‐of‐four to greater than control levels, accompanied by pronounced fade. was found on reversal. In reduced dosage and with careful neuromuscular monitoring, atracurium is safe to use in the myasthenic patient.

The circle system without absorber

An investigation is described into the performance of two types of circle system used without a carbon dioxide absorber in both the laboratory and in the operating theatre with controlled ventilation. The newer system was found to be more efficient than the old but in both types of system the tidal volume was found to be very important, a large tidal volume resulted in increased efficiency. The possibility of predicting arterial blood carbon dioxide using this system is briefly discussed, and rules are suggested for the use of the system.

Carcinoid syndrome with myasthenia gravis. An unusual and interesting case

The anaesthetic management of a patient suffering from carcinoid syndrome and myasthenia gravis is described including the successful treatment of a carcinoid attack with intravenous aprotonin. The differences between myasthenia gravis and the myasthenic (Eaton‐Lambert) syndrome are considered and the rationale for the choice of vecuronium as the muscle relaxant is discussed.

THE CIRCLE SYSTEM WITHOUT ABSORBER. USE WITH CONTROLLED VENTILATION

An investigation is described into the performance of two types of circle system used without a carbon dioxide absorber in both the laboratory and in the operating theatre with controlled ventilation. The newer system was found to be more efficient than the old but in both types of system the tidal volume was found to be very important, a large tidal volume resulted in increased efficiency. The possibility of predicting arterial blood carbon dioxide using this system is briefly discussed, and rules are suggested for the use of the system.

Anaesthetists, lawyers and the public

medicine is now more scientific. The recent recommendations from the Association acknowledge that there is no conclusive evidence of a reduction in mortality or morbidity and are based therefore more on commonsense than science. The Colleges, Faculties and Associations have failed to arrange nationally based schemes to examine practice and determine what is ‘the best’ without the need for the qualifying ‘in my opinion’. The CEPOD report and its companion on maternal mortality are the nearest, but they have yet to tell me the best way to conduct a laparoscopy. Let us not confuse stupidity and arrogance with commonsense and clinical freedom, or believe that there is an unlimited source of funding to procure all for all.

Effect of Acute Hypocapnia on Some Aspects of Renal Function in Anaesthetized Dogs

Hypocapnia was induced in dogs lightly anaesthetized with nitrous oxide and fentanyl. Measurements were made of estimated renal plasma flow (ERPF), glomerular filtration rate, vascular resistance and urine production. During the (short) duration of the experiments hypocapnia was found to be associated with ERPF twice that during normocapnia. Glomerular filtration rate and urine output were increased by hypocapnia in an approximately similar proportion, whilst renal vascular resistance halved. Though some of the experimental animals had a degree of metabolic acidosis this was thought not to have greatly influenced the results.

PHILLIP GETT MEMORIAL LECTURE AWARENESS IN ANAESTHESIA

An attempt is made to assess the importance of awareness and dreaming in patients subjected to light anaesthesia with muscle relaxants. Frank awareness is probably an uncommon event if the anaesthetic be given competently, but unpleasant dreams can, in some circumstances, be significant.