Fig. 2. Interactions of Bispectral Index (BIS) monitoring, anesthetic duration, surgical procedure, and anesthetic technique on time spent in the postanesthesia care unit (PACU). ( Upper left ) Comparison of PACU duration in BIS-monitored patients and controls separated into categories based on anesthetic duration (0–100, 101–200, 201–400, > 400 min). Not significant for BIS-monitored patients versus controls. ( Upper right ) Comparison of PACU duration in four anesthetic groups, separated into categories based on anesthetic duration (0–100, 101–200, 201–400, > 400 min). P < 0.05 by analysis of variance for 0–100, 100–200, and longer than 400 min. ( Lower left ) Comparison of PACU duration in BIS-monitored patients and controls separated into categories based on surgical procedure. ABD = abdominal surgery; FMJ = major body surface surgery; N/A = other surgical procedures; OMI = minor orthopedic surgery; PMJ = major orthopedic surgery, SMI = minor body surface surgery. Not significant for BIS-monitored patients versus controls. ( Lower right ) Comparison of PACU duration in four anesthetic groups separated into categories based on surgical procedure.