Sedation Monitoring Using Frontal Electroencephalogram, Electromyogram and Hemodynamic Responses to Pain in Critical Care

Purpose: Assessing nociception and sedation in mechanically ventilated patients in the ICU is challenging, with few reliable methods available for continuous monitoring. Measurable cardiovascular and neurophysiological variables, such as blood pressure, heart rate, frontal EEG, and frontal EMG, might provide a medium for sedation and nociception monitoring. The hypothesis of this explorative study is that the aforementioned variables correlate with the level of sedation, as described by the Richmond Agitation-Sedation score (RASS). Methods: Thirty adult postoperative ICU patients on mechanical ventilation and receiving intravenous sedation, excluding patients with primary neurological disorders, head injury, or need for continuous neuromuscular blockage. Continuous measurements of bispectral index (BIS), EMG power (EMG), EMG-derived Responsiveness Index (RI), averaged blood pressure variability (ARV), and Surgical Pleth Index (SPI) were tested against repeated RASS measurements, and separately against responsiveness to painful stimuli at varying RASS levels.