Detection of Awareness in Surgical Patients with Patient State Index and Isolated Forearm Technique

Activity: Talk or presentation types › Poster presentation

Description

The aim of this study was to evaluate the ability of electroencephalogram based Patient State Index (PSI) to assess changes in the level of unconsciousness in patients undergoing intravenous induction with propofol followed by sevoflurane anesthesia. We compared PSI with clinical loss of consciousness defined as loss of isolated hand movements to verbal command.. Standard anaesthesia technique was applied for 17 ASA I-III patients by intravenous administration of medication in following order - Fentanyl 1-2 mcg/kg, Propofol 2-3 mg/kg and Atracurium 0.25-0.5 mg/kg. Anesthesia was maintained with sevoflurane 0.8-1.0 MAC and 1-2 mcg/kg/h infusion of Fentanyl. Forearm contralateral to intravenous cannula was isolated for 30 min using arterial tourniquet before each muscle relaxant administration. PSI, isolated hand movement to verbal command, exhaled and inhaled sevoflurane concentration were registered during the induction of anaesthesia, intubation, before, during and after operation and before extubation. Hand movements were defined as specific, non-specific and absence of movement. PSI in the range of 25-50 was considered to indicate optimal hypnotic state for general anesthesia. Presence of intraoperative awareness was assessed using Bruce questionnaire.. After induction of anesthesia and intubation specific hand movements were observed in 41% of patients, 12% showed non-specific hand movements and 47% showed no movement. Before incision specific hand movements were observed in 12% cases. During surgery and immediately after surgery no hand movements were observed. Median PSI after intubation was 34, 31 and 25 in patients who had specific, non-specific and no hand movement (p=0.14). Median PSI before incision was 42 vs 35 in patients with and without hand movement (0.26). No patients reported intraoperative awareness.. There was no significant correlation between PSI indicating adequate hypnosis and absence of movement after induction of anesthesia and before incision. PSI monitoring may not be fully reliable for determining depth of general anesthesia. 
Period29 Mar 2023
Event titleRSU International Research Conference 2023: Knowledge for Use in Practice
Event typeConference
OrganiserRīga Stradiņš University
LocationRiga, LatviaShow on map
Degree of RecognitionInternational

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