Comparative evaluation of methods for the detection of electrodermal responses to multilevel intensity thermal noxious stimuli

Abstract

Purpose In this study, three different methods to identify event-related electrodermal responses (ER.EDRs) were applied, comparing noxious heat stimulation at four different levels. Although the level of heat leading to subjective pain is individual, temperatures above 40 to 45°C are normally experienced as painful due to the stimulation of heat-sensitive nociceptors. Methods Skin conductance (SC) data from 96 healthy participants aged between 18 and 65 years old were analyzed by means of continuous decomposition analysis (CDA), discrete decomposition analysis (DDA), and trough-to-peak analysis (TTP). Several EDR features estimated from these methods were statistically compared. Results Within the analysis window following each single stimulation, CDA and DDA methods identified more electrodermal responses between 1 and 9 s after noxious stimulation than TTP for all stimulation intensities. However, the occurrence rates of at least one ER.EDR after noxious stimulation were similar among the three methods and tended to increase with increasing intensities. Among the common features, amplitude sum had better discriminative power for differentiating noxious stimulation intensities regardless of the method. Conclusion The results suggest that all investigated methods performed similarly in identifying electrodermal changes in response to high-intensity thermal noxious stimuli. In the experimental conditions of cutaneous heat stimulation of nociceptors, good discrimination among stimulation intensities was found using the amplitude sum feature. In conclusion, although CDA and DDA were more sensitive than TTP for identifying ER.EDRs, neither CDA nor DDA brought further discriminative power to the study of noxious stimulation intensities when compared with the traditional TTP method.