Minimum Alveolar Concentration of Desflurane for Maintaining BIS Below 50 in Children and Effect of Caudal Analgesia on it

CONTEXT: Neuraxial techniques have sedative properties secondary to decreased inputs from sensory and motor afferents. We hypothesized that caudal analgesia decreases the requirement of desflurane as measured by bispectral index (BIS). AIMS: This study aims to determine the minimum alveolar concentration (MAC) of desflurane for maintaining BIS below 50 (MACBIS(50)) in children undergoing infraumbilical surgeries with laryngeal mask airway (LMA) and study the effect of caudal analgesia on the same. SETTINGS AND DESIGN: This is prospective and observational study. SUBJECTS AND METHODS: Thirty-nine American Society of Anesthesiologists physical status Classes I and II children in between 1 and 8 years of age undergoing elective infraumbilical surgery under general anesthesia were allocated randomly into two groups (Group C and Group D) after induction with sevoflurane and LMA insertion. In Group C, caudal block was performed with 0.75 mL/kg of 0.25% bupivacaine and BIS values were recorded after 10 min for 1 min at 10 s intervals. In Group D, BIS was recorded for desflurane for 1 min at 10 s intervals followed by a caudal block with the same dose. STATISTICAL ANALYSIS USED: Dixon up-down method with a step size of 0.5%, and probit analysis were used for analysis. RESULTS: A total of 39 patients were enrolled. MAC of desflurane for maintaining MACBIS(50) was 5.57 (95% confidence interval [CI] 5.22–5.95) in Group D and 4.31 (95% CI 3.12–5.08) in Group C. The use of caudal anesthesia lowered the MAC of desflurane for maintaining MACBIS(50) in children by 22.36% (P < 0.001). CONCLUSIONS: The use of caudal analgesia significantly reduced MAC of desflurane for maintaining MACBIS(50) in children undergoing infraumbilical surgeries using LMA.