Pain assessment tool with Electrodermal Activity for post-operative patients: A method validation study (Preprint)
BACKGROUND Accurate objective pain assessment is required in the healthcare domain and clinical settings for appropriate pain management. Automated objective pain detection from physiological data in patients provides valuable information to hospital staff and caregivers to better manage pain, in particular for those patients who are unable to self-report. Galvanic Skin Response (GSR) is one of the physiologic signals that refers to the changes in sweat gland activity, which can identify the features of emotional states and anxiety induced by varying pain levels. In this study, we used different statistical features extracted from GSR data collected from postoperative patients to detect their pain intensity. To the best of our knowledge, we are the first work building pain models using postoperative adult patients instead of healthy subjects. OBJECTIVE The goal of this paper is to present an automatic pain assessment tool using GSR signals to predict different pain intensities in non-communicative postoperative patients. METHODS The study was designed to collect biomedical data from post-operative patients reporting moderate to high pain levels. 25 subjects were recruited with the age range of 23 to 89. First, a Transcutaneous Electrical Nerve Stimulation (TENS) unit was employed to obtain patients' baselines. In the second part, the Empatica E4 wristband was attached to patients while they were performing low intensity activities. Patient self-report based on the NRS was used to record pain intensities used to correlate with the objective measured data. The labels were downsampled from 11 pain levels to 5 different pain intensities including the baseline. Two different machine learning algorithms were used to construct the models. The mean decrease impurity method was used to find the top important features for pain prediction and improve the accuracy. We compared our results with a previously published research study to estimate the true performance of our models. RESULTS Four different binary classification models were constructed using each machine learning algorithm to classify the baseline and other pain intensities (Baseline (BL) vs. Pain Level (PL) 1, BL vs. PL2, BL vs. PL3, and BL vs. PL4). Our models achieved the higher accuracy for the first three pain models in comparison with BioVid paper approach despite the challenges in analyzing real patient data. For BL vs. PL1, BL vs. PL2, and BL vs. PL4, the highest prediction accuracies were achieved when using a Random Forest classifier (86.0, 70.0, and 61.5, respectively). For BL vs. PL3, we achieved the accuracy of 72.1 using a K-nearest neighbors classifier. CONCLUSIONS We are the first to propose and validate the pain assessment tool to predict different pain levels in real postoperative adult patients using GSR signals. We also exploited feature selection algorithms to find the top important features related to different pain intensities. INTERNATIONAL REGISTERED REPORT RR2-10.2196/17783