title: Wavelet transform cardiorespiratory coherence detects patient movement during general anesthesia.
abstract: Heart rate variability (HRV) may provide anesthesiologists with a noninvasive tool for monitoring nociception during general anesthesia. A novel wavelet transform cardiorespiratory coherence (WTCRC) algorithm has been developed to calculate estimates of the linear coupling between heart rate and respiration. WTCRC values range from 1 (high coherence, no nociception) to 0 (low coherence, strong nociception). We have assessed the algorithm's ability to detect movement events (indicative of patient response to nociception) in 39 pediatric patients receiving general anesthesia. Sixty movement events were recorded during the 39 surgical procedures. Minimum and average WTCRC were calculated in a 30 second window surrounding each movement event. We used a 95% significance level as the threshold for detecting nociception during patient movement. The 95% significance level was calculated relative to a red noise background, using Monte Carlo simulations. It was calculated to be 0.7. Values below this threshold were treated as successful detection. The algorithm was found to detect movement with sensitivity ranging from 95% (minimum WTCRC) to 65% (average WTCRC). The WTCRC algorithm thus shows promise for noninvasively monitoring nociception during general anesthesia, using only heart rate and respiration.
authors.affiliation: Department of Electrical & Computer Engineering, University of British Columbia, Vancouver, BC, Canada. chrisb@ece.ubc.ca
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Brouse
authors.forename: Walter
authors.initials: W
authors.lastname: Karlen
authors.forename: Dorothy
authors.initials: D
authors.lastname: Myers
authors.forename: Erin
authors.initials: E
authors.lastname: Cooke
authors.forename: Jonathan
authors.initials: J
authors.lastname: Stinson
authors.forename: Joanne
authors.initials: J
authors.lastname: Lim
authors.forename: Guy A
authors.initials: GA
authors.lastname: Dumont
authors.forename: J Mark
authors.initials: JM
authors.lastname: Ansermino
mesh_terms: D000465:Algorithms; D000768:Anesthesia, General / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D009068:Movement; D010146:Pain / Q000175:diagnosis* / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods*; D015203:Reproducibility of Results; D056152:Respiratory Rate; D012680:Sensitivity and Specificity; D058067:Wavelet Analysis