Abstract
Introduction: EEG derived indices, like Bispectral Index (BIS) and
Spectral Entropy, have been shown to be robust indicators for the depth of
hypnosis during anesthesia. BIS has already been validated in both adults and
children (1). Spectral Entropy has been validated in adults (2), but not in
children. There-fore, the aim of this study was to validate Spectral Entropy
(State Entropy, SE and Response Entropy, RE) (3) as a marker of the level of
hypnosis during general anesthesia in infants and children.
Methods: 20 infants (1 month - 1 year) and 40 children (1-16 years) in good
general health and under-going surgery were included. Premedication was oral
midazolam 0.3 mg/kg. The EEG signal already for the baseline values was
collected with two sensors placed on the forehead. Anesthesia was induced with
5% sevoflurane via face mask with 70% nitrous oxide in oxygen until the loss
of eyelash reflex, fol-lowed by sevoflurane 2% during the venous cannulation.
Thereafter, fentanyl 2 ug/kg and rocuronium 0.5 mg/kg were administered to
facilitate tracheal intubation. Maintenance of anesthesia consisted of
sevoflurane in 70% N2O and 30% O2, together with fentanyl and rocuronium as
needed. All the data of SE, RE, and BIS, end-tidal concentration of
sevoflurane and the vital signs were collected. The level of consciousness was
also measured with Modified Observer’s Assessment of Alertness/Sedation Scale
(OAAS) at various phases. Relationship between SE, RE and BIS values and OAAS
scale was analysed with prediction probability (pk). The pk values for
different indexes were compared using the Wilcoxon rank-sum test, comparisons
of pk values between different age groups were done using the Mann-Whitney
test. Relationship between SE, RE, BIS and end-tidal sevoflurane was analysed
with correlation coefficients.
Results: When all cases were analyzed as a single group, the prediction
probabilities of both SE (p-value 0.04, table, ¤) and RE (p-value 0.04, table,
*) were higher than BIS. The prediction probability in infants was higher
with RE than BIS (p-value 0.02, table, #). The prediction probability of BIS
was better in children than infants (p-value 0.01, table, §). All these
findings in the operation phase were significant. Also there was a significant
inverse correlation between SE, RE, BIS values and the end-tidal
sevoflu-rane.
Conclusion: Our study showed that both spectral entropies (SE & RE) and BIS
reflect reliably the vari-ous phases of anesthesia in infants and children.
Entropy seems to perform more consistently with in-fants than BIS.
| Original language | English |
|---|---|
| Title of host publication | ANESTHESIOLOGY® Annual Meeting Abstract Website |
| Publisher | American Society of Anesthesiologists |
| Publication status | Published - 2004 |