Fractal Properties of Heart Rate Dynamics: A New Biomarker for Anesthesia—Biphasic Changes in General Anesthesia and Decrease in Spinal Anesthesia

Figures

• 

  Figure 1. An example of spinal anesthesia R-R interval spectral analysis. (a) Without any premedication, on the day of surgery, the patient lay in a supine position in a quiet room at least 5 min prior to preanesthetic baseline data collection. (b) Shifting of power by R-R interval spectral analysis 30 min after spinal anesthesia. (c) The sliding window of 60 s shows the shifting power of LF and HF after spinal anesthesia.

• 

  Figure 2. Calculation of DFA. (a) Original R–R interval and integrated time series. (b) The total time series was divided into segments; each segment was then detrended by subtracting the best linear fit F(n). (c) Root mean square of the detrended time series as a function of the segment size n. (d) If the time series is self-similar, a relationship indicates the presence of power law (fractal) scaling. The scaling exponent α can be estimated by a linear fit on the log-to-log plot of F(n) versus n. The α value represents the correlation properties of the time series. The global scaling exponent a value was calculated within the range of n, between n = 4 and n = 165 space. Short-term α1 was calculated between n = 4 and n = 11.

• 

  Figure 3. LF/HF ratio at baseline and post-general anesthesia for Group P (propofol); Group D (desflurane). Box plots show the median, 10th, 25th, 75th, and 90th percentiles as vertical boxes with error bars and plot all data points that lie outside the 10th and 90th percentiles as black circle dots. The significance levels with paired t-tests between baseline and successive measurement periods are as follows: * p < 0.05.

• 

  Figure 4. DFAα1 ratio at baseline and post-general anesthesia for Group P (propofol); D: Group D (desflurane). Box plots showing the median, 10th, 25th, 75th, and 90th percentiles as vertical boxes with error bars and plot all data points outside the 10th and 90th percentiles as black circle dots. The significance levels with paired t-tests between baseline and successive measurement periods are as follows: * p < 0.05; *** p < 0.001.

• 

  Figure 5. LF/HF ratio at baseline and post-spinal anesthesia. (A): Group LM; (B): Group LMf; Box plots showing the median, 10th, 25th, 75th, and 90th percentiles as vertical boxes with error bars and plot all data points outside the 10th and 90th percentiles as black circle dots. The significance levels with paired t-tests between baseline and successive measurement periods are as follows: ** p < 0.01; *** p < 0.001.

• 

  Figure 6. DFAα1 at baseline and post-spinal anesthesia. (A): Group LM; (B): Group LMf; Box plots showing the median, 10th, 25th, 75th, and 90th percentiles as vertical boxes with error bars and plot all data points outside the 10th and 90th percentiles as black circle dots. The significance levels with paired t-tests between baseline and successive measurement periods are as follows: *** p < 0.001.

• 

  Figure 7. Receiver-operating curves analyses of DFAα1 and LF/HF ratio at baseline and postspinal (A) and general anesthesia (B,C) showing fractal analysis of HRV provided a more sensitive and specific information than traditional spectral measurement.