Monitoring Depth of Anesthesia During Opioid Free Anesthesia

Patients who undergo general anaesthesia are more or less extensively monitored, with the sole purpose of surveilling depth of anesthesia and nociception. Parameters such as heart rate, blood pressure, pupillary size and sweating has historically been used as predictive markers for this surveillance. However, these clinical parameters have low predictive capacity and there is a tendency to overdue perioperative sedation and misinterpret sympathetically derived reactions as pain. This could lead to higher incidence of postoperative delirium and opioid induced hyperalgesia. On the contrary, an overestimated trust in the mentioned parameters might lead to increased risk of intra-operative awareness.

The usefulness of processed encephalography (pEEG) during anesthesia has since long been promoted for anesthesia providers. Since then, several commercial devices has been developed and deployed for clinical use. Although mixed results are presented in clinical studies there is now a significant empirical experience for its use in routine anesthesia with volatile anesthetics and propofol. Density spectral array (DSA) is the latest contribution in the field of encephalographic monitoring. It is a two-dimensional graph plotting the power of each frequency-interval on a time-scale.

More and more data on the effectiveness and safety of opioid free anaesthesia (OFA) have been released, especially as a direct result of the ongoing opioid-epidemic affecting a large number of people worldwide. The algorithms for the commercial devices, using DSA, has to this date not been validated for multimodal anesthetic regimens using ketamine and dexmedetomidine.

The purpose of this observational study is to compare DSA pattern and data for pEEG between OFA and total intravenous anaesthesia or general anaesthesia with volatile anesthetics for patients undergoing laparoscopic surgery.