[Prospective epidemiologic study of perioperative anaphylactoid reactions occurring in Catalonia (1996-7)]

To determine the incidence, immunological mechanisms, severity and clinical course of perioperative allergic reactions.

Prospective epidemiological study lasting 2 years (1996-97). In 20 hospitals in Catalonia (Spain), we studied patients who suffered allergic reactions equal to or greater than grade Ib according to the classification of Laxenaire. Serum and urine samples were collected during the first and sixth hours after the onset of a reaction. Complement factors, total serum and latex-specific serum IgE antibodies, hemostatic markers, serum tryptase and urinary methylhistamine were assayed. Tests for allergy to the drugs used during the perioperative period were performed on all patients who consented.

Anesthetic procedures were performed 328,430 times in the 20 hospitals. Thirty-two allergic reactions were reported (1 case/10,263 anesthesias); the frequency was greater during general anesthesia (1 case/6,978 anesthesias). Women suffered 58.3% of the reactions, and the mean patient age was 47.8 +/- 16.5 years. Fifty-six percent of the reactions were severe (grades III-IV), and 68.7% occurred upon immediate exposure. Induction was the moment of greatest risk (50%). Treatment was required by 90.6% of the patients, but no deaths or serious sequelae occurred. Complete analyses could be carried out immediately for 25 patients. High urinary methylhistamine and/or serum tryptase levels were found for 57% of the patients with grade Ib reactions, for 80% of those with grade II reactions, and for 91.7% of those with grade III reactions (p = 0.05). High serum tryptase levels were the only findings for 53.8% of the grade III reactions (p = 0.007). Skin tests were positive for 62.5% of the patients.

The frequency of allergic reactions in Catalonia is 1 case per 10,263 anesthesias performed, but the rate is higher in general anesthesia. Fifty-six percent of the reactions were severe. Most developed immediately and the moment of induction involved the greatest risk. Early assessment of methylhistamine and tryptase levels has been shown to be useful and positivity is linearly associated with severity of reaction. In 62.5% of the patients, positive results were seen in skin tests performed later.