Approximate Entropy of Hypertension: Effect of Anesthesia

Kim, Hee Soo; Yeom, Jong Hoon; Shin, Woo Jong; Kim, Yong Chul; Lee, Dong Ho; Yum, Myoung Gul

Abstract

BACKGROUND
Recently, measurement of heart rate variability and the nonlinear complexity of heart rate dynamics have been used as indicators of cardiovascular health. Hypertensive patients showed alternation of cardiovascular homeostasis. We designed this study to evaluate the effect of anesthesia in hypertensive patients with approximate entropy (ApEn), representing the nonlinear complexity.
METHODS
With informed consent, none premedicated normotensive (n=18) and hypertensive patients (n=18) were included in this study. ECG data were collected from 10 minutes before induction to 15 minutes after induction. Collected ECG data were stored into computer binary files. We calculated ApEn from the collected ECG data.
RESULTS
Before induction, ApEn of hypertensive patients was significantly lower than that of normotensive patients (p<0.05). During induction and maintenance of anesthesia, there was no difference of ApEn between the two groups. ApEn of normotensive patients during induction and maintenance of anesthesia was significantly lower than that of pre-induction (p<0.05). ApEn during maintenance of anesthesia was lower than that of induction of anesthesia (p<0.05). ApEn of hypertensive group during maintenace of anesthesia was significantly lower than that of pre-induction of anesthesia (p<0.05).
CONCLUSIONS
As the ApEn of hypertensive patients is lower than that of normotensive patients during pre-inducton period, the heart rate dynamics of hypertensive patients is more regular normotensive patients. The anesthesia is deepened, the heart rate dynamics of the both group is more regular. During the maintenance of anesthesia, the regularity of the heart rate dynamics that not different in both group from the results.