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. 2015 Jun;59(6):348-52.
doi: 10.4103/0019-5049.158738.

Comparison of electroencephalogram entropy versus loss of verbal response to determine the requirement of propofol for induction of general anaesthesia

Akasapu Karunakara Rao  1 , Indira Gurajala  2 , Ramachandran Gopinath  2
Affiliations

Comparison of electroencephalogram entropy versus loss of verbal response to determine the requirement of propofol for induction of general anaesthesia

Akasapu Karunakara Rao et al. Indian J Anaesth. 2015 Jun.

Abstract

Background and aims: Propofol causes dose-dependent reduction in blood pressure (BP). This study was done to evaluate the use of spectral entropy on the dose of propofol required and the haemodynamic stability during induction of general anaesthesia (GA).

Methods: In this randomised controlled study, 72 American Society of Anesthesiologists' physical status I and II patients undergoing general and orthopaedic surgeries were divided into Group S (n-36) and Group C (n-36). Patients in Group C were induced with propofol till loss of response to verbal commands and in Group S until the state entropy was <50 and state and response entropy difference was <10. The induction dose of propofol, haemodynamic parameters and the entropy values were recorded. Numerical data were expressed as a mean ± standard deviation and analysed using unpaired, two-tailed t-test. Categorical data were compared using Chi-square test. P < 0.05 value was considered significant.

Results: The dose of propofol per kg was significantly more in the entropy group (1.80 ± 0.23 mg/kg in the Group C and 1.98 ± 0.217 mg/kg in the Group S [P < 0.05]). After induction, at intubation and 1 min after intubation, entropy values were lower in Group S than Group C (P < 0.05). The BP decreased significantly after induction compared with the baseline (P < 0.05), but there was no difference between the groups.

Conclusion: Propofol required for induction of GA when guided by electroencephalogram entropy was significantly higher than the induction dose based on loss of verbal response. Both conventional induction and induction with entropy as the endpoint resulted in similar haemodynamic profile.

Keywords: Electroencephalogram entropy; induction dose; propofol.

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Conflict of interest statement

Conflict of Interest: None declared

Figures

Figure 1
Figure 1
The dose of propofol required for induction of anaesthesia in the control and study group. * - P < 0.05 between the groups
Figure 2
Figure 2
Entropy recordings in the control and study groups at baseline, induction, intubation and 1 min after intubation. SE - State entropy, RE - Response entropy * - P < 0.05 between the groups
Figure 3
Figure 3
Heart rate in the control and study groups at baseline, induction, intubation and 1 min after intubation. B - Baseline, IND - Induction, INT - Intubation, INT1 - Intubation at 1 min. * - P < 0.05 between the groups
Figure 4
Figure 4
Blood pressure in the control and study groups at baseline, induction, intubation and 1 min after intubation. B - Baseline, IND - Induction, INT - Intubation, INT1 - Intubation at 1 min, SBP C - Systolic blood pressure control, SBP S - Systolic blood pressure study, DBP C - Diastolic blood pressure control, DBP S - Diastolic blood pressure study. x - P < 0.05 indicating a significant decrease in blood pressure after induction when compared to baseline in both groups
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