Higuchi fractal dimension as a measure of analgesia

Avoidance of patients' intraoperative awareness and explicit recall of pain during surgery is important. Conventional methods of depth of anesthesia (DoA) monitoring involve physiological monitoring which are influenced by the administered anesthetic drugs. Balanced anesthesia is fusion of its four components analgesia, amnesia, motor blockade and hypnosis. One major component is analgesia which means inability to feel pain during surgery. Pain cannot be estimated any single physio-pathological signal. A proper analgesia index proportional to the degree of pain experienced by the patient is required. Electroencephalogram (EEG) is a reliable means to determine real time DoA. In the present study, EEG of 12 volunteer subjects was recorded during relaxed and during pain. It was found that the Higuchi fractal dimension (HFD) feature of EEG from parietal region of brain reflects the sensation of pain and gives an overall accuracy of 95% in determining the pain experienced by the patient.