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

July 18, 2026 updated by: İlke Dolgun, Istinye University

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

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

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

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Postoperative pain intensity assessed using the Visual Analog Scale (VAS)
Time Frame: 10 minutes, 30 minutes, 4 hours, 8 hours, 12 hours, and 24 hours after surgery
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Time to first breastfeeding
Time Frame: Within the first postoperative hour
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

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Need for rescue analgesia
Time Frame: Within the first 24 hours after surgery
The proportion of patients requiring additional postoperative analgesia was recorded.
Within the first 24 hours after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Istinye University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 15, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 15, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 15, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 18, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 18, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 22, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 22, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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