Nociception Level Index Monitoring During Cesarean Section (NOL-CS)

Effect of Nociception Level Index-Guided Intraoperative Analgesia on Postoperative Pain Management During Elective Cesarean Section

This prospective randomized controlled trial evaluated the effect of nociception level (NOL) index-guided intraoperative analgesia on postoperative pain management in patients undergoing elective cesarean section under general anesthesia. Sixty patients were randomly assigned to either NOL-guided analgesia or standard intraoperative monitoring. The primary outcome was postoperative pain intensity assessed using the visual analog scale (VAS) during the first 24 hours after surgery. Secondary outcomes included postoperative opioid requirements and time to first breastfeeding. The study aimed to determine whether objective intraoperative nociception monitoring could improve postoperative analgesia and enhance early maternal recovery.

Study Overview

• Status: Completed
• Conditions: Cesarean Section; Pain Management; Postoperative Pain After Cesarean Section
• Intervention / Treatment: Device: Nociception Level Index Monitoring; Other: Standard Intraoperative Monitoring

Detailed Description

Postoperative pain following cesarean section remains an important clinical concern because inadequate analgesia may delay maternal recovery, increase opioid consumption, and negatively affect early breastfeeding and maternal-infant bonding. Conventional intraoperative monitoring does not directly assess nociceptive responses, making individualized analgesic administration challenging.

The Nociception Level (NOL) index is a multiparametric monitoring system that integrates photoplethysmography, galvanic skin response, peripheral temperature, and accelerometer signals to provide an objective assessment of nociception during anesthesia. This technology may enable more individualized opioid administration based on the patient's nociceptive response.

In this prospective randomized controlled trial, patients undergoing elective cesarean section under general anesthesia were randomized to receive either NOL-guided intraoperative analgesia or standard intraoperative monitoring. In the intervention group, fentanyl administration after fetal delivery was guided by the NOL index, whereas patients in the control group received conventional hemodynamic-guided analgesia.

Postoperative pain was evaluated using the visual analog scale (VAS) at predefined time points during the first 24 postoperative hours. Rescue opioid requirements, total postoperative analgesic consumption, and time to first breastfeeding were also recorded. The study was designed to determine whether NOL-guided analgesia could improve early postoperative pain control and reduce postoperative opioid requirements compared with conventional monitoring.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Sultangazi
    • Istanbul, Sultangazi, Turkey (Türkiye), 34256
      • University of Health Sciences Türkiye Haseki Training and Research Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Female patients undergoing elective cesarean section under general anesthesia.
• Ability to provide written informed consent.

Exclusion Criteria:

• Refusal to participate.
• Emergency cesarean section.
• High-risk pregnancy (including hypertensive disorders of pregnancy, diabetes mellitus, preterm labor, or fetal growth restriction).
• Placental abnormalities.
• History of allergy to any study medication.
• History of malignant hyperthermia.
• Alcohol or substance abuse.
• Severe cardiac disease or severe arrhythmia.
• Peripheral vascular disease.
• Renal or hepatic failure.
• Contraindication to corticosteroid administration.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: NOL-Guided Analgesia Group; Patients undergoing elective cesarean section under general anesthesia were monitored intraoperatively using the Nociception Level (NOL) index in addition to standard monitoring. After fetal delivery, fentanyl was administered in 25-mcg boluses when the NOL value remained above 25 for more than 1 minute, with a minimum interval of 5 minutes between doses.	Device: Nociception Level Index Monitoring; The Nociception Level (NOL) index was used to guide intraoperative fentanyl administration after fetal delivery.
Active Comparator: Standard Monitoring Group; Patients undergoing elective cesarean section under general anesthesia received standard intraoperative monitoring. Intraoperative analgesic management was performed according to conventional clinical practice without NOL index guidance.	Other: Standard Intraoperative Monitoring; Standard intraoperative monitoring was used for routine anesthetic and analgesic management without NOL index guidance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative pain intensity assessed using the Visual Analog Scale (VAS)	Postoperative pain intensity was evaluated using a 10-cm Visual Analog Scale (VAS), where 0 indicated no pain and 10 indicated the worst imaginable pain.	10 minutes, 30 minutes, 4 hours, 8 hours, 12 hours, and 24 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to first breastfeeding	The time elapsed from the end of surgery until the first successful breastfeeding was recorded in minutes.	Within the first postoperative hour

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Need for rescue analgesia	The proportion of patients requiring additional postoperative analgesia was recorded.	Within the first 24 hours after surgery

Collaborators and Investigators

• Sponsor: Istinye University

Study record dates

Study Major Dates

• Study Start (Actual): August 15, 2023
• Primary Completion (Actual): February 15, 2024
• Study Completion (Actual): February 15, 2024

Study Registration Dates

• First Submitted: July 18, 2026
• First Submitted That Met QC Criteria: July 18, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 18, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative Pain; Breastfeeding; Cesarean Section; Opioid Consumption; General Anesthesia; Nociception Level Index; NOL Index; Nociception Monitoring; Intraoperative Analgesia
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Postoperative Complications; Pathologic Processes; Neurobehavioral Manifestations; Perceptual Disorders; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Feeding Behavior; Pain, Postoperative; Agnosia; Breast Feeding
• Other Study ID Numbers: HASEKI-36-408-2023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No