OPTIMIZATION OF INTRAOPERATIVE ANALGESIA DURING LIVING DONOR LIVER RESECTION USING ANALGESIA NOCICEPTION INDEX (ANI)

Introduction. Currently, objective methods for optimizing intraoperative analgesia, such as the Analgesia Nociception Index (ANI), are being applied. ANI provides a non-invasive assessment of autonomic nervous system dynamics during surgery, with a particular focus on parasympathetic activity and can contribute to the objectification of opioid dosing. Excessive opioid dosing may contribute to postoperative adverse effects, including nausea and vomiting. Fentanyl elimination significantly changes during its infusion due to context-sensitive half-life [21]. It is practically impossible to adjust an infusion dose based on a subjective evaluation of the autonomic nervous system. Aim. The aim of this study was to assess whether intraoperative analgesia nociception monitoring (ANI) could reduce the average intraoperative dose of fentanyl and, consequently, the incidence of postoperative nausea and vomiting. Materials and methods. This study was conducted on two groups of patients – living liver donors during liver resection and in the early postoperative period (48 hours): the ANI group (n = 24), in which the fentanyl dose was adjusted using ANI monitoring, and a retrospective control group (n = 25) with standard practice of subjective evaluation of the parasympathetic nervous system (heart rate, blood pressure) without ANI monitoring. All patients received sevoflurane general anesthesia, intraoperative intravenous fentanyl infusion, rocuronium, and thoracic epidural analgesia. Results. There was a 36.63 % decrease in the average dose of fentanyl in the ANI group (1,28 (±0,48) mcg•kg-1•h-1) compared to the control group (2,02 (±0,46) mcg•kg-1•h-1) (p < 0,001). There was also a decrease in the incidence of postoperative nausea and vomiting: 33.33 % in the ANI group and 44 % in the control group. However, this difference was not statistically significant (p = 0.636). Conclusions. We suggest that ANI monitoring may be used to guide fentanyl infusion dosing during living donor liver resections, reducing the average dose compared to standard practice. The impact of ANI on PONV remains inconclusive – in this study and in most published reports, there was no statistically significant difference in reducing PONV incidence after surgery, likely due to small sample sizes, low opioid doses, heterogeneity of surgical procedures, and prophylactic use of antiemetics.