[Allergic reactions and pseudoallergies in surgical interventions with general anesthesia]

The Spanish Societies of Allergology and Anesthesiology have established a protocol for action for the performance of allergy tests for anesthesia. The protocol was published by the General Directorate of INSALUD, along with an informed consent form for general and loco-regional anesthesia, on 30 June 1994. Despite this, demands for care and requests for allergologic and anesthetic studies have increased. This review examines the diagnostic, preventive, and therapeutic criteria for adverse reactions during general anesthesia according to the most relevant international literature. Pseudoallergic reactions are one of the most frequent and important adverse reactions that occur during general anesthesia. These reactions are caused by the release of histamine and, probably, other mediators. The histamine-releasing effect depends on the dose of the medication. The most potent medications are morphine and almost all muscular relaxants, in the following proportions (succinylcholine: 43%; vecuronium: 37%; pancuronium: 13%; alcuronium: 76%; atracurion: 6.8%; galamine: 56%). Somewhat less than 50% of all severe intraoperative allergic reactions are really anaphylactoid reactions. The mediators involved in anaphylactic/anaphylactoid responses are: IgE in type I hypersensitivity mechanisms, IgA, immunocomplexes, complement activated by an alternative pathway, tryptase, and histamine. Numerous and varied agents are involved. Table III lists general intravenous anesthetics; table IV shows muscular relaxants. According to national studies, intraoperative latex sensitization occurs in 1% to 5% of health-care personnel and 40% of children with spina bifida. More than 6% of blood donors have IgE against latex. Cross-reactions between latex and fruit proteins, such as banana and kiwi, have been reported. As many as 50% of patients with latex allergy have such cross-reactions, according to some authors. Diagnostic methods include skin tests, challenge, histamine release test, RIA, human basophil optical degranulation test, and ImmunoCAP. Skin tests are the technique most often used in Allergology Units in Spain. Risk factors are debated. Although the female sex is accepted as predominant, atopy is controversial. The only known negative factor is the insertion of an endotracheal tube in asthmatic patients. Prevention should begin with the selection of less potent drugs, such as histamine releasing agents. Slow administration of drugs, as opposed to bolus administration, has been demonstrated to be more effective. The use of combined H1 and H2 antihistamines as a preanesthetic medication can significantly reduce tachycardia/bradycardia, hypotension, skin response, and even gastric pH changes induced by histamine release.