The effects of caudal local anesthesia blockade on the Bispectral Index during general anesthesia in children.
BACKGROUND
Peripheral deafferentation induced by epidural or spinal anesthesia reduces the degree of cortical arousal in adults. This study aimed at determining if caudal blockade decreases the level of arousal, as measured by Bispectral Index (BIS) in unstimulated children, and to determine if this effect differed between age groups.


METHODS
Hospital ethics committee approval and parental consent was obtained. Children (age between 24 months and 5 years) and infants (between 6 and 24 months of age) were recruited if they were scheduled for below umbilical surgery that would usually require caudal local anesthesia blockade. Before the procedure, subjects within each age group were randomized to either caudal group (1 ml.kg(-1) 0.25% bupivacaine), or control group (no caudal). In all groups, anesthesia was induced with sevoflurane and maintained at a constant endtidal concentration of 1.5% sevoflurane without N(2)O. Five minutes after induction a baseline BIS was recorded (BIS(1)). In the caudal groups, a caudal block was then performed while in the control groups no block was performed. Fifteen minutes later, the BIS was again recorded (BIS(2)). The change in BIS over this time period was the primary outcome (BIS(Delta)). After measurement, subjects in the control groups received a caudal block before the start of surgery.


RESULTS
Twenty-nine infants and 18 children completed the study protocol. In children, BIS(Delta) was significantly different between the caudal group and control (-5.7 vs -0.7, P = 0.04). In infants, no significant difference was detected in BIS(Delta) between caudal and control groups.


CONCLUSIONS
Caudal blockade decreased the degree of arousal, as measured by BIS, in unstimulated children aged 2-5 years. No change in arousal was detected in infants.
Davidson
Andrew J
AJ
Department of Anaesthesia and Pain Management, Royal Children's Hospital, Parkville, VIC, Australia. andrew.davidson@rch.org.au
Ironfield
Craig M
CM
Skinner
Adam V
AV
Frawley
Geoff P
GP
D000704:Analysis of Variance; D000763:Anesthesia, Caudal; D000768:Anesthesia, General; D000769:Anesthesia, Inhalation; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D001143:Arousal / Q000187:drug effects*; D002045:Bupivacaine; D002675:Child, Preschool; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects / Q000379:methods; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008738:Methyl Ethers; D016343:Monitoring, Intraoperative; D009609:Nitrous Oxide; D000077149:Sevoflurane; D013519:Urogenital Surgical Procedures
D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide; D002045:Bupivacaine