Correlation between BIS and layered behavior of heart rate in children under general anesthesia

Yum, Myung Kul; Kim, Hyun Joo; Kim, Jin Tae; Kim, Chong Sung; Kim, Seong Deok; Kim, Hee Soo

Clinical Research

Pediatric Anesthesia

Anesthesia and Pain Medicine 2008;3(4):327-329.
Published online October 30, 2008.

Correlation between BIS and layered behavior of heart rate in children under general anesthesia

Myung Kul Yum, Hyun Joo Kim, Jin Tae Kim, Chong Sung Kim, Seong Deok Kim, Hee Soo Kim

¹Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Korea. dami0605@snu.ac.kr
²Department of Pediatrics, Hanyang University College of Medicine, Seoul, Korea.

Abstract

BACKGROUND
The bispectral index (BIS) is based on changes in the electroencephalogram, and is commonly used to monitor depth of anesthesia. The central nervous system (CNS) controls heart rate variability (HRV). The purpose of this study was to examine the relationship between heart rate variability and changes in BIS.
METHODS
We recruited 33 patients, aged 2-12 years. On arrival at the operating room, electrocardiograph (ECG), SpO2, noninvasive blood pressure, and BIS were monitored. After induction and intubation, patients were ventilated with sevoflurane in 35% oxygen in air. At a tidal volume of 7 ml/kg, the respiratory rate was adjusted to maintain an end-tidal CO2 of 35-40 mmHg. Inspired and expired end-tidal sevoflurane concentrations were held constant at 1.0 or 2.5 vol% for more than 10 minutes, after which ECG and BIS data were obtained for 15 minutes. Low-frequency power (LFP), highfrequency power (HFP), approximate entropy (ApEn), maximum layered behavior indices (MaxLI), and mean layered behavior indices (MeanLI) were calculated from the ECG. The relationship between mean BIS and variability indices at the two sevoflurane concentrations was measured by Pearson's correlation coefficient.
RESULTS
MaxLI and MeanLI were positively correlated to BIS; whereas LFP, HFP, and ApEn were not.
CONCLUSIONS
BIS and ECG indices are correlated during sevoflurane anesthesia in children, and thus ECG-derived indices could be used to monitor depth of anesthesia.

Key Words: BIS, children, heart rate variability, sevoflurane