Using photoplethysmography imaging for objective contactless pain assessment

Abstract

This work presents an extension to the known Analgesia Nociception Index (ANI), which provides an objective estimation of the current depth of analgesia. An adequate "measure" would facilitate so-called balanced anesthesia. Generally, ANI is computed using heart rate variability or rather beat-to-beat intervals based on an electrocardiogram (ECG). There are clinical situations where no ECG monitoring is available or required, but only photoplethysmography (PPG), e.g., in some cases in postoperative care or pain therapy. In addition, a combination of PPG and ECG for obtaining beat-to-beat intervals may lead to increased robustness and reliability for dealing with artifacts. This work therefore investigates the computation of ANI using standard PPG. In addition, new methods and opportunities are presented using contactless PPG imaging (PPGI). PPGI® enables contactless PPG recordings for deriving beat-to-beat intervals as well as analysis of local perfusion and wounds. © Czech Technical University in Prague, 2014.