High levels of impulsivity may contraindicate midazolam premedication in children.

Purpose: To investigate the effects of midazolam on emotional reactivity during induction of anesthesia in a pediatric day surgery setting. A secondary purpose was to determine if these effects were influenced by child temperament factors.

Methods: Forty children (age four to six years) scheduled for myringotomy were randomly assigned, in a double blind fashion, to receive either oral midazolam 0.5 mg.kg-1 mixed with acetaminophen suspension or acetaminophen alone. The Emotionality, Activity, Sociability, and Impulsivity (EASI) scale was used as a measure of child temperament. The modified Yale Preoperative Anxiety Scale (m-YPAS), an observer-rated measure of state anxiety, was employed to assess anxiety pre- and post-drug, and also at induction of anesthesia.

Results: Children who received midazolam reacted significantly less to induction of anesthesia than did children in the placebo control group, F (1, 38) = 7.46, P = 0.01. A significant positive association was observed between baseline levels of anxiety and observer-rated anxiety at anesthetic induction, but only in the placebo group, r = 0.58, P < 0.01. A significant positive association was observed between levels of impulsivity at baseline and observer-rated anxiety at anesthetic induction, but only in the midazolam group, r = 0.42, P < 0.05.

Conclusions: Midazolam dampened adverse reactivity during anesthetic induction, particularly among children with high baseline levels of anxiety. Baseline level of impulsivity was positively associated with adverse reactions to anesthesia induction in the drug group, but not in the placebo group, suggesting that high levels of trait impulsivity may contraindicate the use of midazolam as a preoperative medication.