Journal of Biomedical Imaging and Bioengineering

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Monitor sedline®: is it effective to monitor intraoperative awareness?

To assess if there is a relationship between intraoperative awareness and the use of Sedline® monitor in patients under general intravenous anaesthesia. Observational, descriptive and cross-sectional study performed between 2014 and 2015 in 93 patients. We excluded: patients premedicated with benzodiazepines or opioids, not extubated in the operating room, under 18 years or with a history of neurological or psychiatric alterations. Sedline® obtains the Patient State Index (PSI), which is a value for classifying anaesthetic depth. The reference values are: 100-70: Aware patient.70-50: Sedation.25-50: Ideal Anaesthetic Depth. 0-25: Deep Anaesthetic Plane. We use Brice questionnaire to evaluate intraoperative awareness. The variables are age, sex, weight, ASA, BMI, type and duration of surgery, PSI values at baseline, induction, 5 minutes postinduction, surgical incision and extubation. Statistical significance level p<0.05. The incidence of intraoperative awareness was zero. Seven patients reported intraoperative dreams. With a PSI>39 in induction, 10.2% had dreams, whereas those with a value of less than 39 had only 3.3% dreamed (p>0.05). Of the total sample, at induction, the average PSI value was 49.83 (DS18.70) with values greater than 50 at 37.6%. During extubation, 44.1% of the patients had PSI<70, of which 6.5% woke up with values below 50. There were no cases of intraoperative awareness. Seven cases had dreams, 6 of them had a PSI value at induction greater than 39. It could suggest that values above 39 at induction are related to the possibility of dream recall. In the total sample the average PSI value during induction was very close to 50, which corresponds to the upper limit to be in the optimum state of hypnosis. The PSI value in extubation is below 70 in 44.1%. This value does not assure the reliable awakening state for the patient.

Author(s): Elena Garcia