Prevention of anaphylactic reactions to anaesthetic drugs.

Although screening tests to prevent anaphylaxis during anaesthesia have been advocated, such tests are unlikely to have significant impact on reducing the incidence of anaphylaxis during anaesthesia. This is due to the low prevalence of the disease, the diversity of drugs used in anaesthesia and the incidence of false positive and negative tests. The suggested risk factors of allergy, i.e. atopy, asthma, family history, female sex, previous exposure, vasectomy, use of zinc protamine sulfate insulin and allergy to cosmetics, eggs, fish and non-anaesthetic drugs are not valid. Although all have theoretical or real associations with anaphylaxis during anaesthesia the majority of patients with such a history undergo uneventful anaesthesia. Fruit allergy, anaphylaxis to cephalosporins and penicillin, barbiturate allergy, gelatin allergy and allergy to metabisulphite and eggs require consideration in avoiding particular drugs. The incidence of anaesthetic anaphylaxis can be reduced by avoiding latex exposure in patients with spina bifida or latex allergy, and preventing second reactions in patients with a history of anaphylaxis, or major undiagnosed or undocumented adverse events during anaesthesia. Determining the cause of an adverse event and the drug responsible, and adequately communicating those findings can reduce second reactions. Avoiding neuromuscular blocking drugs (NMBDs) in patients who have reacted to an NMBD, and use of non-intravenous techniques should also reduce the incidence of second reactions. Desensitisation, and blocking with monovalent quaternary ammonium compounds may allow improved safety of NMBDs and pretreatment with antihistamines and corticosteroids may block or ameliorate the severity of reactions, but there is currently little evidence to support their routine use.