Indian Journal of Anaesthesia (Jan 2008)
Comparative Evaluation of Spectral Entropy and Bispectral Index during Propofol/Thiopentone Anaesthesia in Patients with Supratentorial Tumours - A Preliminary Study
Abstract
Previous studies have confirmed the usefulness of Bispectral index (BIS) and spectral entropy in non-neurosurgical patients. The effects of thiopentone or propofol on BIS and entropy in patients with supratentorial tumours have not been studied. To address the above issue, we carried out a prospective, randomised controlled trial to determine the correlation between BIS, Response entropy and State entropy during different stages of induction of anaesthesia in neurosurgical patients. Twenty ASA I/II patients of either gender, aged 19-58 years undergoing excision of supratentorial tumour were selected for the study. The BIS was recorded using A-2000 BIS monitor (Aspect medical systems, Newton, MA) and entropy monitored with Datex-Ohmeda S/5 entropy module (Helsinki, Finland) at various stages of induction of anaesthesia, using either thiopentone or propofol as the induction agent. We found that BIS and Entropy parameters correlated strongly at different stages of induction. The correlation was significant between BIS and Entropy at baseline, after fentanyl administration, after induction, and after intubation. We also noted that Entropy parameters unlike BIS are not affected by haemodynamic response due to intubation. To conclude, Entropy may be considered a valid indicator of the effects of thiopentone and propofol during different stages of induction of general anaesthesia neurosurgical patients.
