Utilización de parámetros derivados de la señal fotopletismográfica (ppg) para la valoración de dolor inducido experimentalmente en sujetos sanos: estudio de factibilidad

Abstract

Given the need to assess pain experienced by patients in an adequate and objective way, several efforts have been made to determine whether it is possible to assess the pain suffered by an individual through physiological indicators. However, most of these efforts have focused on evaluating the response of subjects to thermal or, even, electrical stimuli, and very little evidence exists on the feasibility of detecting and/or quantifying the intensity of pain experimentally induced by mechanical stimuli. In addition, the use of multiple parameters can bring complications during implementation, electrical risk and discomfort for the subject. Based on this, the objective of this study was to assess whether it is possible, through certain parameters derived from the photoplethysmographic signal (PPG), to detect the presence or absence of pain caused by mechanical stimuli. The three parameters used were heart rate, PPG signal amplitude (PPGA), and the high-frequency component of heart rate variability. Fifteen healthy subjects (11 men and 4 women; between 18 and 45 years old) voluntarily participated in the study, after signing an informed consent. A mechanical stimulus was applied at three different intensities: 3, 6 and 9 N, for approximately 3 seconds, and the variations of the chosen parameters were captured through an acquisition circuit and a processing algorithm programmed in the MATLAB environment. The results obtained suggest that, even though the three parameters were able to distinguish pain from no pain, only the heart rate was able to differentiate between low and medium pain levels, as well as low and high pain levels. However, it was shown that, regardless of tensity, a mechanical stimulus capable of inducing pain could significantly influence the parameters analyzed. Future work could include a larger number of participants and randomize the application of the stimulus.