D3.45 - Perioperative Immediate Hypersensitivity Reactions: First Chilean Cohort Study 2020-2024 Clinical Hospital University of Chile

Immediate hypersensitivity reactions (IHR) in the perioperative setting are a medical challenge, due to multiple simultaneous drug use, surgery related factors and exposure to hidden agents. The sensitization profiles are influenced by geographic factors, related mainly to drug exposure. 

Objective: To describe the epidemiology, clinical presentation and sensitization profile of Chilean patients with perioperative IHR.

A descriptive cross-sectional study of patients evaluated for suspected IHR in perioperative context, who underwent an allergological study at the Clinical Hospital University of Chile, Allergy Center, between January 2020 and December 2024, was performed. The clinical records, in vivo and in vitro allergological studies were retrospectively analyzed.

A total of 78 patients were included, with 45 active agents tested. Median age of 47 years (range 10-83) with a female predominance (78%). The main clinical presentation was anaphylaxis (70.5%), of which 57.7% were grade III or above. Cardiovascular symptoms were reported in 91% of anaphylaxis, while grade I reactions predominantly involved mucocutaneous symptoms. Most of the reactions occurred during anesthetic induction (58%) and recovery (24%). 68% of patients were studied within the first year after the event. Positive results were observed in 17% of skin prick tests and 74% of intradermal reactions. Specific IgE to latex was performed in 23% of patients, with 6.4% positivity, ascending to 9% in anaphylaxis cohort. Sensitization was confirmed in 81% of the cases. The main cause for perioperative IHR was neuromuscular blockers (NMBs) (37%), primarily Atracurium (24%), followed by Rocuronium (18%). Beta-lactam antibiotics, involved in 22% of cases, with Cefazolin (19%) as the primary culprit. Other causes included opioids (8%, led by Methadone), Chlorhexidine (8%), hypnotics (6%), latex (6%), non-steroidal anti-inflammatory drugs (5%, all due to Metamizole), and Ondansetron (5%).

NMBs and antibiotics were the most frequent triggers, consistent with studies from Europe and Asia. However, the frequency of Methadone, Metamizole and Latex, differed, reflecting local influences. This is the first descriptive study on perioperative allergic reaction performed in Chile, provides data from Latin America and highlights the need to monitor local sensitization patterns and pharmacological use, to develop prevention strategies.