Nociception Monitors: A comparison based on different clinical cases

Abstract

Maintaining a good level of anesthesia along a surgery is essential both for intraoperative and postoperative outcomes. General anesthesia is a combination of a hypnotic effect, to achieve an unconscious level, and an analgesic effect, to relief or inhibit nociception. Up to present, analgesia was administered based on clinical signs during surgery. However, in the recent years new monitors have been developed based on different technologies in order to advise doctors on the amount of analgesia they have to manage. Since these monitors are quite new in the market, there is not enough study that accurately establishes their performances. Hence, the aim of this work is to compare several nociception indices computed by four different devices: the Conox, the ANI, the Algiscan and the qCO. Three objectives are addressed: to see how similar the monitors are between them, to assess the performance of each device based on the prediction of the nociception response and to identify some parameters that could be interfering the prediction. The correlation of 43 surgeries with Conox, qCO, and Algiscan and 13 surgeries with ANI was done to calculate the similarity between these monitors. The prediction probability (Pk) was computed and a statistical significance test was performed in order to assess the capability of each index to predict the nociception response. Finally, to identify the parameters that were affecting the monitors, the mean and the standard deviation (SD) of different groups based on the index prediction performances were calculated. From the obtained results it can be concluded that the qNOX index computed with the Conox and the parameters based on pupil size computed with Algiscan data, were able to predict the nociception response to Tetanus stimulus with a Pk>0.75. Nevertheless, the age and the Burst Suppression were affecting the qNOX index in a bad way. Finally, the ANI monitor shows moderate correlation with the HFn index of the qCO monitor, while the qNOX most correlate with the Algiscan index.