PAIN-RELATED HEART RATE VARIABILITY RESPONSES IN THE CONTEXT OF EXPERIMENTAL PAIN STIMULATION

Objective pain assessment is still an ongoing issue in health sciences, and the analysis of Heart Rate Variability (HRV) is considered a promising tool to provide quantitative information regarding pain sensation. However, commonly used HRV analysis comprises features determined in longer time-periods (at least five minute length recordings), which might be impractical for the development of some online monitoring systems. Thus, we aimed to analyze 10 time- domain features using ultra-short HRV analysis in the context of thermal-induced painful stimulation. Electrocardiographic data from 85 participants from the Biovid Pain Database were analyzed. Ten time-domain features were extracted from pre- and post-stimulation periods using 10-second duration windows. Then, after normal distribution assessment with Lilliefors normality test, we compared intra-group variability by means of paired t-test. Three features (SDNN, RANGE and HR) significantly increased after stimulation, while two features (pNN20 and MEAN) decreased. Further, the higher the stimulation intensity, the larger the number of sensitive features. Although we suppose that the analysis of lower intensities stimulation was impaired by the short inter-stimuli interval duration, SDNN, RANGE, pNN20, MEAN and HR seem to be feasible time-domain features to assess experimental pain by means of ultra-short HRV analysis.