A Randomized Controlled Trial to Determine the Effect of Depth of Anesthesia on Emergence Agitation in Children

BACKGROUND: The cause of emergence agitation (EA) in children is unknown. Rapid emergence from inhaled anesthesia has been implicated because EA is more common with sevoflurane than with halothane. A dose-dependent effect of sevoflurane, which increases seizure-like electroencephalogram activity, has also been proposed. METHODS: To determine whether depth of anesthesia as measured by bispectral index (BIS) affects EA, 40 ASA physical status I to II children aged 2 to 8 years undergoing ophthalmic surgery were enrolled in a blinded randomized controlled trial of low-normal (40-45, deep) versus high-normal (55-60, light) anesthesia. To distinguish transient irritability from severe EA, the primary outcome was first-stage postanesthesia care unit (PACU I) peak Pediatric Assessment of Emergence Delirium (PAED) score, with secondary outcomes of PAED and Face, Legs, Activity, Cry, and Consolability scores at emergence, postoperative fentanyl dose, emergence time, and discharge time. Subjects received a standard anesthesia protocol with oral midazolam followed by mask induction with sevoflurane 8%, fentanyl 1 to 1.5 mu g/kg IV (then as needed), neuromuscular blockade, and endotracheal intubation. Providers titrated expired sevoflurane (in N2O 67%) from 0.5% to 3% to maintain BIS range. PAED, Richmond Agitation Sedation Scale, and Face, Legs, Activity, Cry, and Consolability scores were measured at emergence, at PACU I arrival, and during PACU I stay. RESULTS: There was little difference between the groups in the primary outcome, peak PACU I PAED score (light: 7.7 +/- 4.6; deep: 8.6 +/- 5.3; mean difference, 0.9; 95% confidence interval, 4.1 to -2.3; effect size, 0.18). Discharge times were similar between groups. Treatment for severe EA was rare. CONCLUSIONS: There was no significant effect of BIS-guided deep versus light anesthesia on severe EA.