Clinical Study attributes
Most critically ill patients receive sedative and analgesic drugs to attenuate discomfort and pain. The excessive use of sedatives and analgesics has undesirable effects for patients. Whereas undersedation is mostly easy to identify, oversedation with its associated problems is more difficult to recognize. Stopping sedation daily helps to avoid gross oversedation, but this is not always possible. Monitoring the depth of sedation is difficult and is currently based on clinical assessment and the use of clinical scoring systems. These scoring systems cannot be applied continuously, they are subjective and the level of consciousness can be altered when sedation is assessed. Several methods based on the electroencephalogram have been tested to avoid these problems, but the results have been disappointing so far, so the BIS Monitor an dthe Entropy monitor.We have previously shown that the time-locked cortical response to standard external stimuli (long-latency auditory evoked potentials or event-related potentials; ERPs) can discriminate between clinically relevant light to moderate and deep sedation levels in healthy volunteers, when sedation is induced with a combination of propofol or midazolam with remifentanil. We therefore hypothesized that ERPs may be used to monitor the depth of sedation in ICU patients as well. As the first step to test this hypothesis, we evaluated the use of ERPs to assess the level of sedation in patients undergoing elective major surgery and admitted to the ICU for short term postoperative mechanical ventilation.
