New method for pain evaluation：2nd report; correlation with VAS

Objective: In the dental field, there are many kinds and intensities of pain. Pain is generally evaluated based on the patient's subjective expression using VAS (visual analog scale) and FS (face scale). It is necessary for the dentists to evaluate pain objectively in order to estimate the pain of pre- and post- treatment more accurately. Following the first report, this study evaluated the correlation between objective data from wavelet analysis of ECG voltage fluctuation and subjective data from VAS, and we investigated whether or not wavelet analysis of ECG voltage fluctuation is applicable in the clinical field. Methods: The subjects were 9 healthy volunteers (35±5.0 years). Clamp application was performed around the right lower first molar of these subjects for one minute as an experimental pain stimulation. During experimentation, ECG was measured continuously using RADARCIRC (electrocardiograph for pain monitoring; Dainippon Sumitomo Pharma. Co., Ltd.). A subjective method of evaluating pain, VAS, was used at the same time. As objective data on pain, ECG voltage fluctuation from the 3rd lead (left collarbone-left under rib) during clamp application was assessed by wavelet analysis using FLUCLET (fluctuation analyzing software; Dainippon Sumitomo Pharma.Co., Ltd.), and the area under the spectral amplitude curve (AUC) was evaluated. In analysis, the correlation between VAS and AUC was examined employing Spearman's rank correlation coefficient. Results: There was a significant correlation between AUC and VAS on clamp application (correlation coefficient: r=0.75, p<0.05). Conclusion: Wavelet analysis of ECG voltage fluctuation using RADERCIRC and FLUCLET showed a correlation with a subjective evaluation method, VAS. The results suggests that our new method for pain evaluation can be applied in the clinical dental field. Further, it will be available as a new objective method for analyzing pain intensity in the near future.