Comparison of Opioid Consumption During Target Controlled Infusion (TCI) Guided By Nociception Level Index (NOL) or Standard Care Undergoing Intracranial Tumor Surgery

Muhammet Esat Demirel,1,* Hulya Bilgin,2,* Selcan Akesen2 1Department of Anesthesiology, Bursa City Hospital, Bursa, Türkiye; 2Department of Anesthesiology, Bursa Uludağ University Faculty of Medicine, Bursa, Türkiye*These authors contributed equally to this workCorrespondence: Muhammet Esat Demirel, Email [email protected]: This prospective, randomized controlled study aims to compare opioid doses in patients undergoing intracranial tumor surgery managed with Total Intravenous Anesthesia using Target Controlled Infusion (TIVA-TCI) combined with Nociception Level (NOL) monitoring. The NOL index, an artificial intelligence–driven multiparameter index, integrates physiological signals such as heart rate, skin conductance, and photoplethysmography to provide an objective measure of nociception and guide personalized opioid administration. Additionally, the study evaluates the consumption of hypnotic drugs, hemodynamic parameters, variability in the NOL index, and changes in Heart Rate (HR) in the study group patients who received NOL monitoring following severe noxious stimuli.Patients and Methods: The study involved 50 ASA II–III patients undergoing intracranial tumor surgery, with 25 in the standard care guided group and 25 in the NOL guided group. The control group received standard monitoring while NOL monitoring added in the study group. Propofol and remifentanil were titrated to maintain hemodynamic parameters or NOL values. Hemodynamic parameters, propofol and remifentanil doses were recorded and compared between groups. NOL index changes before and after noxious stimuli were compared with HR changes.Results: No significant differences were found in demographic data between the two groups. The remifentanil dose administered was similar in both groups. The study group received a higher dose of propofol. However, the control group had a longer duration of operation. The NOL index showed a significantly higher change after severe noxious stimuli compared to Heart Rate, indicating greater sensitivity.Conclusion: This study compares NOL index monitoring to standard monitoring during intracranial tumor surgery. The results indicate that NOL monitoring is reliable in detecting and monitoring nociception events compared to heart rate changes. However, it does not lead to a significant reduction in opioid dose administration.Keywords: target controlled infusion, intracranial tumor surgery, intraoperative nociception monitoring, NOL index monitoring, opioid