Comparison of the Surgical Pleth Index and the Nociception Level Index in the Pediatric Population

Comparison of the Surgical Pleth Index and the Nociception Level Index in the Pediatric Population: An Observational Study

This observational study aims to compare two nociception monitoring methods. The Nociception Level (NOL) index and the Surgical Pleth Index (SPI) in the pediatric population during general anesthesia. While both monitors are designed to assess nociceptive responses through autonomic nervous system activity, they differ in methodology and parameters measured. The NOL index integrates multiple physiological signals using a self-learning algorithm, while SPI focuses on heart rate variability and plethysmographic amplitude. Although both have been studied individually in children, a direct comparison has not yet been conducted. This study will evaluate and compare each monitor's ability to detect and quantify nociceptive stimuli (surgical and tetanic) in children.

The investigators hypothesize that the NOL monitor and SPI monitor will both be able to quantify surgical stimuli and tetanic stimuli with monitors response to surgical stimuli > monitors response to tetanic stimuli. However, the investigators also hypothesize that the NOL index will do this superiorly, as it utilizes a self-learning algorithm and more parameters are incorporated in its algorithm

This is a single centre, observational prospective non-interventional study. The study will take place at the Radboudumc. After obtaining informed consent participants will be enrolled. Each participant will be treated according to the standard Radboudumc anaesthesia protocol with heartrate monitoring, respiratory rate monitoring, neuromuscular monitoring (TOF-Watch SX ) , intermittent non-invasive blood pressure monitoring and Bispectral index monitoring. Participants will be connected to the NOL index PMD-200 device using the finger probe and the SPI device (Carescape b650) using the pulse oxymeter directly after induction of anesthesia with propofol/sevoflurane. Before start of surgery, after recording a period of 30 seconds with no stimulation (no nociception) a standardised tetanic stimulus of 5 seconds with 60 mA and 100hz will be applied with the neuromuscular monitor on the patients ulnary nerve trajectory with two adhesive electrodes. This is a stimulus that is part of common anesthesiology practice in order to assess the patients neuromuscular blockade. Previous research has used tetanic stimuli of similar intensity as standardised nociceptive stimuli in order to validate nociception monitors. After SPI and NOL monitor values return to baseline (pre-tetanic stimulus value) surgery with first incision will commence.

During the operation the response to the standardised stimuli and nociceptive events such as intubation, insertion of supraglottic airway, surgical incision and administration of opioids will be registered by a trained researcher. After surgery, upon discharge to the anaesthesia recovery room, patients will be disconnected from both monitors. Post-operative pain/comfort scores and post-operative analgesia usage will be registered by the researcher at the recovery room. Total duration of the study inclusion period is expected to be 1 year.

Inclusion Criteria:

• Male or female
• ASA I, ASA II and ASA III
• Aged 1 to 12 years old
• Scheduled to undergo elective surgery with general anaesthesia

Exclusion Criteria:

• Patients with chronic pain
• Patients with chronic analgesia usage.
• Known allergy to the adhesives used in the sensors.
• No free available limb to attach the probes to.