Detrended Fluctuation Analysis Used in Heart Rate Variability to Assess the Depth of Anesthesia

In this paper, a detrended fluctuation analysis (DFA) method is applied to assess the depth of anesthesia. General assessment of the depth of anesthesia (DoA) method is monitoring the cerebral cortex activity. The purpose of this study is to develop a new index which is different from the cerebral cortex activity monitoring index. Forty surgery patients (25 males + 15 females) were investigated. For every patient, the procedure is divided into three stages, before surgery 5 minute (stage A), during the surgery (stage B) and after the surgery 5 minute (stage C). The DFA values of each patient were calculated, and the mean ± standard deviation of DFA in 40 patients were calculated. Calculated results show that patients before surgery α, α1 and α2 values were 0.795 ± 0.188, 0.862 ± 0.165 and 0.839 ± 0.200, during surgery were 0.696 ± 0.353, 0.650 ± 0.107 and 0.690 ± 0.215, and after surgery were 0.803 ± 0.195, 0.871 ± 0.172 and 0.846 ± 0.209. The results have been shown significant differences (P < 0.05) in α and α2 values (including stages A and B, stages A and C) and none significant difference in α1 value (any two stages combination A, B and C). Therefore, the value of α and α2 have index effect in distinguish the physiological characteristics of patients before and after anesthesia.