RESUMO
Background: Benzodiazepines are used for perioperative conscious sedation. However, its use may be associated with paradoxical reactions. The known risk factors for these reactions are age, alcohol and drug abuse and psychiatric disorders. Aim: To assess the incidence and impact of risk factors of paradoxical reactions to midazolam. Material and Methods: Cross sectional study of 218 patients aged 50 ± 16 years (51% women) scheduled for elective surgical procedures under regional anesthesia and midazolam sedation. The paradoxical reactions were classified according to their severity in three categories. Results: The incidence of paradoxical reactions to midazolam was 8.3% (95% confidence interval (CI) 5.0-12.7). All were mild and only 28% of the affected patients required pharmacological treatment, none of them flumazenil. A multivariable logistic regression model showed that the variables independently associated with a paradoxical reaction to midazolam were the use of psychoactive medications (Odds Ratio (OR) = 3.4 [1.1-11], p = 0.04, and the dose of midazolam (OR 1.35 [1.03-1.78], p = 0.03. Conclusions: The incidence of paradoxical reactions to midazolam was 8,3% and all were mild. Their risk factors are the use of psychoactive medications and the use of higher doses of midazolam.