Caudal Block Reduces Demand of Sevoflurane for Adequate Depth of Anesthesia in Children

Song, Jang Ho; Lee, Hong Sik; Kim, Byung Gun; Lim, Hyun Kyoung; Shinn, Helen Ki; Jung, Sung Mee

Abstract

BACKGROUND
It is generally known that neuraxial anesthesia for adults reduces the demand for hypnotics needed for adequate sedation. Therefore, this study examined the effect of a preoperative caudal block on the general anesthetic requirements for an adequate depth of anesthesia in children.
METHODS
Twenty children aged 3-5 years, who were set to undergo inguinal herniorraphy, were divided into 2 groups of 10 children each, normal saline and lidocaine groups. Tracheal intubation was performed. After setting up the bispectral index (BIS) monitor, a caudal block was administered to both groups differently, normal saline 0.7 ml/kg was administered to the normal saline group and 1.5% lidocaine 0.7 ml/kg was administered to lidocaine group. The end-tidal concentration of sevoflurane was maintained at 1.5 vol% for 10 minutes in the first patient in both groups, and the BIS value, was measured 6 times every 10 seconds, and averaged. When the BIS was > or = 50, the end-tidal concentration of sevoflurane was increased by 0.2 vol% in the subsequent patient. When the BIS was less than or equal to 50, the end-tidal concentration of sevoflurane was decreased by 0.2 vol% in the subsequent patient. The MAC(BIS50) in both groups was calculated using probit analysis. Relative median potency analysis was used to compare the results in both groups.
RESULTS
The MAC(BIS50) of sevoflurane was significantly lower with a 1.5% lidocaine caudal block (1.40 vol% [95% CI, 1.25-1.55 vol%]) compared with the normal saline group (1.77 vol% [95% CI, 1.61-2.00 vol%]).
CONCLUSIONS
A preoperative caudal block reduces the demand for sevoflurane required for an adequate depth of anesthesia, as measured by the BIS in children.