Evaluating the Efficacy and Utility of the Automated Pupillometer in Pain Assessment and Opioid Administration Guidance During the Perioperative Period: A Randomized Controlled Trial

May 20, 2026 updated by: YEAP CHUN HONG, University of Malaya

Effective intraoperative and postoperative pain management is critical for patient comfort and recovery, yet traditional methods for assessing pain under general anaesthesia are limited by their subjective nature and reliance on vital signs. Automated pupillometry, which gives the parameters of the pupillary light reflex (PLR) components, offers an objective and quantitative approach to evaluating nociception and pain.

This study aims to evaluate the effectiveness of the automated pupillometry in enhancing early postoperative pain control and to assess its utility in guiding opioid administration during the perioperative period.

A prospective, non-blinded randomized controlled trial will be conducted with 68 patients undergoing laparotomy for gastrointestinal surgery. Participants will be randomly assigned to either an interventional group, where analgesia is guided by automated pupillometry measurements, or a control group receiving standard pain management. Key outcomes include the time to first rescue analgesia, self-reported pain scores, opioid consumption. The automated pupillometry measurements will be taken at key surgical moments, including before induction, pre-incision, and during recovery.

Pain scores and rescue analgesia use will be compared between groups using appropriate statistical tests, and Kaplan-Meier survival curves will analyze time to first rescue analgesia. Regression analyses will explore the relationship between pupillometry readings and postoperative pain.

It is anticipated that the automated pupillometry guided group will experience longer intervals before requiring rescue analgesia and report lower pain scores, suggesting improved pain management and reduced opioid use.

This study could validate automated pupillometry as an innovative tool for optimizing postoperative pain management, potentially improving patient outcomes by enabling more precise and effective analgesia in surgical settings.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

68

Phase

  • 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

  • Malaysia
    • Kuala Lumpur
      • Kuala Lumpur, Kuala Lumpur, Malaysia, 59100
        • Universiti Malaya Medical Centre

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 1. Patients aged 18 - 70 years old scheduled for elective/emergency laparotomy with clear awareness and good communication
  • 2. ASA (American Society of Anaesthesiologists) physical status I-III
  • 3. Expected to have moderate to severe pain in the early postoperative period

Exclusion Criteria:

  • 1. Patient with known pupillary abnormality (such as anisocoria, pharmacologic dilation, previous intraocular surgery)
  • 2. Pre-existing neurological disorder affecting pupillary reflexes
  • 3. Patients on chronic opioid therapy or with a history of substance abuse
  • 4. Non-consenting patients or those with cognitive impairments affecting informed consent

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
Intervention / Treatment
Active Comparator: Intervention

Participants in the interventional group will receive an initial dose of 100 mcg IV fentanyl during induction. Remifentanil will be administered via effect-site target-controlled infusion (TCI), with a concentration effect (Ce) ranging from 2 to 8 ng/ml, titrated according to the anaesthetist's discretion. TCI remifentanil is increased by 0.5 ng/ml if pupillary diameter changes > 20% of the baseline. Automated pupillometry will be measured before induction , after induction(baseline), before the surgical incision, after surgical incision and during skin closure. Additional analgesics could be administered as control arm.

At the post anaesthesia recovery area, PLR will be measured at 10 min and at 30 min.Anaesthetists will give rescue morphine when the pupillary diameter changes > 20% and repeat the measurement after 5 minutes
Drug: Opioid Analgesic
Participants in the interventional group will receive an initial dose of 100 mcg IV fentanyl during induction. Remifentanil will be administered via effect-site target-controlled infusion (TCI), with a concentration effect (Ce) ranging from 2 to 8 ng/ml. TCI remifentanil is increased by 0.5 ng/ml if pupillary diameter changes > 20% of the baseline after induction. The automated pupillometry measurement is repeated 5 mins after increment. Prior to skin closing, IV morphine 0.1 mg/kg during skin closing and automated pupillometry measurement is repeated to aim pupillary diameter is within 20% of baseline. Analgesics is titrated according to the anaesthetist's discretion and reason is documented if it is deviated from the protocol.
Device: automated pupillometry

For both arms, automated pupillometry will be measured before induction , after induction(baseline), before the surgical incision, after surgical incision, during skin closure, at PACU 10 mins and at PACU 30 mins.

For intervention arm only, the additional automated pupillometry measurement will be performed after administration of analgesia.
Other: Control
Participants in the control group will receive anaesthetic and analgesic management as per the standard practice followed by the attending anaesthetist. Additional analgesics, including intravenous paracetamol, intravenous parecoxib, and abdominal plane blocks, will be provided if there are no contraindications. Automated pupillometry will be measured before induction , after induction(baseline), before the surgical incision, after surgical incision and during skin closure. At the post anaesthesia recovery area, PLR will be measured at 10 min and at 30 min.
Device: automated pupillometry

For both arms, automated pupillometry will be measured before induction , after induction(baseline), before the surgical incision, after surgical incision, during skin closure, at PACU 10 mins and at PACU 30 mins.

For intervention arm only, the additional automated pupillometry measurement will be performed after administration of analgesia.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
post operative opioid consumption
Time Frame: first 24 hours post operatively
the amount of post operative opioid consumption including rescue analgesia and patient controlled analgesia morphine usage would be recorded
first 24 hours post operatively

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The correlation between pupillary response metrics (% change, constriction velocity, dilatation velocity, NPi) and opioid dosage administered.
Time Frame: automated pupillometry measurements will be done before induction, after induction, before skin incision, during skin incision, after skin incision, during skin closure, and at post anaesthesia recovery unit 10 min and 30 min.
To find the measurement changes or correlation with opioiod administration, and to analyse it statistically
automated pupillometry measurements will be done before induction, after induction, before skin incision, during skin incision, after skin incision, during skin closure, and at post anaesthesia recovery unit 10 min and 30 min.

Collaborators and Investigators

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

Sponsor

University of Malaya

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)

May 1, 2026

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

February 1, 2027

Study Registration Dates

First Submitted

May 20, 2026

First Submitted That Met QC Criteria

May 20, 2026

First Posted (Actual)

May 29, 2026

Study Record Updates

Last Update Posted (Actual)

May 29, 2026

Last Update Submitted That Met QC Criteria

May 20, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 202541314965
  • BKP004-2025-ECRG (Other Grant/Funding Number: EARLY CAREER RESEARCH GRANT (BKP-ECRG) 2025 UNIVERSITI MALAYA)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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