Nociception level response to calibrated stimulations in children: First assessment of the nociception level index in pediatric anesthesia.

Introduction: Intraoperative monitoring of nociception has made great progress in adult anesthesia. However, pediatric data are scarce. The Nociception Level (NOL) is one of the most recent indexes of nociception. Its originality is that it provides a multiparametric assessment of nociception. In adults, NOL monitoring allowed lower perioperative opioid requirements, hemodynamic stability, and qualitative postoperative analgesia. So far, the NOL has never been used in children. Our objective was to validate the ability of NOL to provide a quantitative assessment of nociception in anesthetized children.

Methods: In 5-12 years old children anesthetized with sevoflurane and alfentanil (10 µg kg), before surgical incision, we performed three standardized tetanic stimulations (5 s, 100 Hz) of different intensities (10-30-60 mA) in a randomized order. NOL, heart rate, blood pressure and Analgesia-Nociception Index variations were assessed after each stimulation.

Results: Thirty children were included. Data were analyzed with a covariance pattern linear mixed regression model. NOL increased after the stimulations (p < 0.05 at each intensity). NOL response was influenced by stimulation intensity (p < 0.001). Heart rate and blood pressure were barely modified by the stimulations. Analgesia-Nociception Index decreased after the stimulations (p < 0.001 at each intensity). Analgesia-Nociception index response was not influenced by stimulation intensity (p = 0.064). NOL and Analgesia-Nociception Index responses were significantly correlated (Pearson r = 0.47; p < 0.001).

Conclusions: NOL allows a quantitative assessment of nociception under anesthesia in 5-12 years-old children. This study provides a solid basis for all future investigations on NOL monitoring in pediatric anesthesia.

Registration: NCT05233449.