Is halothane obsolete? Two standards of judgement

Professor Weis and Dr Engelhardt (Anaesthesia 1989; 4 4 97-100) have again! given their view that double standards are applied in the criticism of various drugs and techniques in anaesthesia. Their argument is based, first on the risks from halothane being less, and sometimes considerably less, than those of other potentially lethal drugs or techniques. Second, because the animal models do not exactly conform to the human scenario, animal data are of little relevance. Third, since the tests used to establish the diagnosis of halothane-associated hepatitis are positive in less than 100% of patients (believed on clinical grounds to be so afflicted), then the tests have little validity, and finally, as the alternative agents may also cause hepatitis (although this may be an event of even greater rarity) the advantage of those alternatives must be viewed with scepticism. Halothane-associated hepatitis continues to cause morbidity and, very rarely, mortality despite warnings against its use in specific patients known to be peculiarly at risk.* Surely the tragedy of even a solitary avoidable anaesthesiarelated death is not diminished simply because its cause is not fully established or is of extreme rarity? The Confidential Enquiry into Peri-operative Deaths3 (CEPOD) has established that the contemporary risk of avoidable death attributable to anaesthesia alone is of the order of 1 in 185 000. To be fair, none of the 4034 deaths included in the CEPOD report was attributed to hepatitis associated with halothane. The evidenceb7 for the existence of fulminant halothaneassociated hepatitis based on antibody studies should not be overlooked. Similarly, the frequent occurrence of transient, and seemingly clinically insignificant, elevation of liver function enzymes after halothane cannot be denied,”-” especially when this appears to occur less readily after the alternative volatile agent~ . l*-~~ The incidence of liver dysfunction is considerably higher in some groups of patients: for instance, Zaric and colleagues1° found that approximately one in 300 postoperative patients (four cases) aged 45 years or older, with otherwise unexplained nausea, vomiting or pyrexia, had altered liver function tests. Two of these four cases developed severe liver failure. As Weis and Engelhardt have already stressed,! the risks of a particular anaesthetic cannot be considered apart from the overall risks of anaesthesia. Currently there are fewer fatal cases in Britain each year of maternal aspiration of