Background: Perioperative anaphylaxis or anaphylactoid reaction is an uncommon event and difficult to diagnose. Clinical symptoms range from mild with skin lesion to serious life-threatening conditions.

Objective: To describe characteristics of patients who developed anaphylaxis or anaphylactoid reaction during anesthesia including signs, symptoms, treatment, outcome, and suggestive strategies for perioperative anaphylaxis or anaphylactoid reaction in Thailand.

Materials and Methods: A prospective descriptive study was conducted by using data from first 2,000 incident reports of the Perioperative and Anesthetic Adverse Events in Thailand [PAAd Thai] study. Patient characteristic and detail of anaphylaxis including signs, symptoms, probable causes, treatment, and immediate outcome were recorded. All data were reviewed by three experienced anesthesiologists. Descriptive statistics was used.

Results: After reviewed, 70 incidents were identified as perioperative anaphylaxis or anaphylactoid reaction. Anaphylaxis occurred more commonly in female. Most (98.5%) were ASA I-III with mean age 42.6±2.5 years. Seventy-two-point-nine percent of events occurred during general anesthesia. By using clinical severity, patients were classified as grade I, II, III, in 38, 4, and 28 patients, respectively. Suspected causes were identified in 41 cases. The most common causes were antibiotic, blood component, and colloid, in 13, 9, and 6 cases, respectively. Clinical manifestations of grade III were hypotension, rash or urticarial, bronchospasm, tachycardia, and angioedema, in 21, 18, 15, 11, and 5 patients, respectively. Only 19 from 28 patients in grade III received adrenaline treatment. All patients in grade I and II recovered completely. In grade III, surgery was postponed in five cases and two cases were admitted to ICU. Only one patient received serologic test and skin test.

Conclusion: To improve outcome, guidelines for perioperative anaphylaxis management should be followed. After anaphylaxis event, proper investigation to identify definite cause should be done at proper time.

Keywords: Anaphylaxis, Anaphylactoid reactions, Allergic reactions, Perioperative, Adverse event, Drug allergy