Effectiveness of Analgesia Nociception Index (ANI) As a Monitoring Tool to Evaluate Intraoperative Pain in Pediatric Patients Undergoing Sevofluorane Sedation and Locoregional Anesthesia

Background: We present our results about pediatric patients undergoing sevofluorane sedation and locoregional anesthesia (LRA) referred for visceral, urological and orthopedic surgery, using Analgesia Nociception Index (ANI) as a monitoring tool for intraoperative pain. Objective: The aim of this study was to evaluate the effectiveness of ANI to provide assessment of locoregional anesthesia success (opiod-free anesthesia) following skin incision in pediatric patients sedated with sevofluorane. Materials and Methods: We enrolled 60 patients aged 2-17 years from September 2022 to November 2022. All patients were eligible for locoregional anesthesia, not suffering from cardiac arrhythmias, neurological disorders and not treated with opioids or drugs interfering with Autonomic Nervous System. Following preoperative assessment and consent, premedication with midazolam (0,5 mg/Kg per os) was used. Standard monitoring (SpO2 , HR, ECG, NIBP, body temperature sensor) and ANI was placed prior to induction of anesthesia. Once intravenous access had been established, anesthesia was induced with sevofluorane or propofol, was maintained with sevofluorane (MAC 1.3 in oxygen) and then ultrasound guided locoregional anesthesia was performed. ANI values were recorded prior to skin incision (T0) after 30 seconds (T1) and after 2 minutes (T2) from skin incision. A rise in HR≥10% from baseline occurring within the 2 minutes after skin incision was considered to be a LRA failure, which requires fentanest (1-2 γ/Kg). A rise in HR<10% from baseline occurring within the 2 minutes after skin incision was instead considered LRA success, not requesting opioid. Results: 43 patients presented LRA success and 17 patients presented LRA failure. In the LRA failure group, skin incision caused ANI values decrease (p<0,05) within 30 seconds from skin incision. We described that ANI<68 in the first 2 minutes following skin incision can identify LRA failure with a sensitivity of 100% and a specificity of 82.4% (AUC:0.984). Conclusion: ANI values rapidly decrease after skin incision in case of LRA failure and this tool, alone or in combination with HR changes, could guide anesthesiologists in using intraoperative opioid in children over 2 years of age sedated with sevofluorane.