Assessment of Diabetic Autonomic Nervous Dysfunction with a Novel Percussion Entropy Approach

Figure 1

Computation of percussion rate by matching changes in the amplitudes (Amp, defined as the height of a waveform from foot point to peak) of n successive photoplethysmography (PPG)-acquired digital volume pulse (DVP) waveforms with changes in R-R intervals (RRI) using a shift number (s) of 1 and the dimension of vector pattern (m) (i.e., impact points) of 2. Note that n = 1000 for the present study. PPG: photoplethysmography; EKG: electrocardiogram; Amp(n): amplitude of DVP waveform during cardiac cycle; RRI(n): R-R interval during cardiac cycle; a: binary code denoting increase (i.e., 1) or decrease (i.e., 0) in amplitude when compared with the previous waveform; r: binary code denoting increase (i.e., 1) or decrease (i.e., 0) in RRI when compared with the previous cardiac cycle.