  Variations of instantaneous heart rate appears regularly oscillatory in
deeper levels of anesthesia and less regular in lighter levels of anesthesia.
It is impossible to observe this "rhythmic-to-non-rhythmic" phenomenon from raw
electrocardiography waveform in current standard anesthesia monitors. To
explore the possible clinical value, I proposed the adaptive harmonic model,
which fits the descriptive property in physiology, and provides adequate
mathematical conditions for the quantification. Based on the adaptive harmonic
model, multitaper Synchrosqueezing transform was used to provide time-varying
power spectrum, which facilitates to compute the quantitative index:
"Non-rhythmic-to-Rhythmic Ratio" index (NRR index). I then used a clinical
database to analyze the behavior of NRR index and compare it with other
standard indices of anesthetic depth. The positive statistical results suggest
that NRR index provides addition clinical information regarding motor reaction,
which aligns with current standard tools. Furthermore, the ability to indicates
the noxious stimulation is an additional finding. Lastly, I have proposed an
real-time interpolation scheme to contribute my study further as a clinical
application.
