Wavelet transform cardiorespiratory coherence for monitoring nociception

Heart rate variability (HRV) may provide anesthesiologists with a noninvasive tool for nociception monitoring during general anesthesia. A novel wavelet transform cardiorespiratory coherence (WTCRC) algorithm was used to calculate estimates of the linear coupling between heart rate and respiration. WTCRC was tested on clinical data from 19 pediatric patients receiving general anesthesia during dental surgery. WTCRC decreased during nociception, and increased following additional anesthetic drugs. Data were divided into categories with normal respiratory rate (RR) (in the HF band) and low RR (in the LF band), then split into 2-minute windows. WTCRC and LF/HF were calculated for each window and compared in each category. The algorithms showed correlations of -0.5506 and -0.1403 for data with normal and low RR, respectively. WTCRC and LF/HF are comparable when the RR is normal, and WTCRC significantly outperforms when the RR is low.