New method for pain evaluation：1st report; analysis method

Objective: Recently, it was reported that low frequency components (LF; 0.04Hz～0.15Hz) of electrocardiogram (ECG) voltage fluctuation by wavelet analysis were changed depending on the existence of cancer pain. The report suggests the likelihood that can evaluate pain objectively. In this study, we analyzed the change of LF during lode the experimental pain stimulation in the intraoral space and investigated whether or not this method would be applicable in dental clinical fields. Methods: The subjects were 5 healthy volunteers (29.0±1.5 years). Gingival retraction was performed around the maxillary right central incisor of these subjects as the experimental pain stimulation. During experimentation, ECG voltage fluctuation from the 3rd lead (left collarbone - left under rib) was measured using RADARCIRC (electrocardiograph for pain monitoring; Dainippon Sumitomo Pharma. Co., Ltd.) and FLUCLET (fluctuation analyzing software; Dainippon Sumitomo Pharma. Co., Ltd.). The cubic spline function was determined from the time series of R wave potentials of ECG. The spline function was re-sampled at 1 kHz and analyzed with wavelet method. In analysis, the area under the curve of LF amplitude (AUC) in the rest condition was compared that in the experimental pain stimulation using Wilcoxon signed-ranks test (significance level; p < 0.05). Results: There was a significant difference (p < 0.05) between AUC in the rest condition (0.44±0.12 mV/min·rootHz) and that in the experimental pain stimulation (2.83±1.29 mV/min·rootHz). Conclusion: Even if the experimental pain stimulation was loaded in intraoral space as well as cancer pain awareness time, a change of AUC was confirmed. This suggests that objective evaluation of pain will be enabled by reviewing the change of LF obtained by wavelet analysis of ECG voltage fluctuation in dental clinical fields.