Comparison of bispectral index (BIS) and entropy in patients with cerebral palsy during sevoflurane induction

Kim, Nam Yeop; Lee, Il Ok; Lim, Byung Gun; Kim, Hee Zoo; Kong, Myoung Hoon; Lee, Mi Kyoung; Lim, Sang Ho; Kim, Nan Suk

Abstract

BACKGROUND
Demand of anesthesia for patients with cerebral palsy is more increasing. But there is still lacking in clinical research regarding how BIS and entropy reflect well on sedative and hypnotic state in patients with cerebral palsy.
METHODS
Fifteen patients with cerebral palsy (Group CP) and fifteen patients without cerebral palsy (Group NL) scheduled for elective orthopedic surgery were included in the study. Induction of anesthesia was done by having the patient inhale 1 vol% sevoflurane and 100% oxygen using a total fresh gas flow of 8 L/min. Simultaneously BIS, state entropy (SE), response entropy (RE), end-tidal sevoflurane concentration were recorded every 15 seconds till there was no self respiration. When end-tidal sevoflurane concentration had not risen any more for 30 seconds, we increased inhaled sevoflurane concentration in 1 vol% increments. End point of recording was when self respiration was lost or the time sevoflurane concentration reached 8 vol%.
RESULTS
No significant differences in RE, SE, BIS at baseline and end point were found between the two groups. No significant difference in the time reach end point was found between the two groups. BIS, SE and RE correlated with end-tidal sevoflurane concentration in the two groups.
CONCLUSIONS
The authors found no significant difference in the entropy values between patients with CP and normal patients. Also, the entropy values could be interpreted like BIS in patients with CP. And BIS showed a stronger correlation with end tidal sevoflurane concentrations than entropy.