Pupillary Pain Index to Evaluate Interscalene Block and Postoperative Pain in Patients Underwent Shoulder Surgery

Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center , Taipei, Taiwan

When an individual encounters nociceptive pain stimuli, the pupil dilates in a unique manner known as Pupil reflex dilation (PRD).The degree of pupillary reflex dilatation can be further quantified into an objective parameter, termed the Pupillary pain index (PPI), as a monitoring tool for the balance between nociception and antinociception in surgical patients The motivation for this study is to investigate the feasibility of using pupillometry to assess acute pain after shoulder surgery. The purpose of the study is as follows: (1) Can PDR in patients undergoing general anesthesia be used to assess the analgesic effect of interscalene block? (2) Does PPI at the end of surgical anesthesia in such patients correlate with the first numerical pain scale (NRS) during the recovery room?

Study Overview

• Status: Completed
• Conditions: Surgery; Shoulder Impingement
• Intervention / Treatment: Procedure: Patients scheduled to undergo shoulder rotators repair surgery

Detailed Description

When an individual encounters nociceptive pain stimuli, the pupil dilates in a unique way called pupillary reflex dilation (PRD), which can be observed both when the individual is awake or under anesthesia. The degree of pupillary reflex dilatation can be further quantified into an objective parameter called the Pupillary pain index (PPI), which serves as a monitoring tool for the balance between nociception and antinociception in surgical patients. Larson studied 32 female breast surgery patients who received general anesthesia combined with thoracic paravertebral nerve block on the affected side. The results showed that the affected side of the nerve block had significantly lower pupillary reflex dilation than those without nerve block on the healthy side of the breast. The authors believed that this study confirmed the value of pupillary reflex dilation in monitoring the success rate of unilateral thoracic paravertebral nerve block during general anesthesia. In a prospective observational study of 26 patients undergoing neurosurgery under general anesthesia, Pupillary pain index at the end of surgical anesthesia and Numerical Rating Scale (NRS) during the recovery room were recorded separately, The results showed a significant correlation between the two parameters (rS = 0.62; P = 0.002). The authors concluded that the application of the measurement of pupillary reflex dilation may be useful in predicting and preventing acute postoperative pain. Shoulder rotator muscle repair is a common surgery in our hospital. Patients must receive general anesthesia, sometimes combined with scalene interscalene block (ISB), to improve postoperative acute pain ,help to perform passive shoulder rehabilitation exercises and prevent shoulder joint adhesions. Based on the above literature review, the motivation for this study was to investigate the feasibility of using pupillometry to assess acute pain after shoulder surgery. The objectives of the research project are as follows: 1. Can pupillary reflex dilation in patients undergoing general anesthesia be used to assess the analgesic effect of scalene nerve block? 2. Is the pupillary pain index (PPI) at the end of surgical anesthesia correlated with the first numerical pain scale (NRS) during the recovery room in such patients?

• Study Type: Observational
• Enrollment (Actual): 40

Contacts and Locations

Study Locations

• Taiwan
  • Taipei, Taiwan, 114
    • Department of Anesthesiology, Tri-Service General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients scheduled to undergo shoulder rotators repair surgery

Description

Inclusion Criteria:

• Patients who received general anesthesia combined with ipsilateral interscalene block
• Patients listed as a Class I/II physical condition of the American Society ofAnesthesiologists

Exclusion Criteria:

• Patients younger than 20 years of age
• The presence of ophthalmologic (recent eye surgery or cataracts) or neurologic diseases (diabetic neuropathy,or postherpetic neuralgia) that could interfere with Pupillometer

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
shoulder rotators repair; Patients scheduled to undergo shoulder rotators repair surgery	Procedure: Patients scheduled to undergo shoulder rotators repair surgery; Patients scheduled to undergo shoulder rotators repair surgery, and received combined general anesthesia and interscalene block

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pupillary Pain Index (PPI )	The primary outcome is the difference of the pupillary pain index (PPI ) between the ISB side and the control side The PPI mode applies a standardized, incremental transcutaneous electrical stimulation (100 Hz, 10-60mA, with 1-s intervals) that progressively increases in intensity until a pupil dilation of >13% is observed. The degree of reflex dilation is quantified on a scale of 1 (very deep analgesia) to 9 (very light analgesia) and referred to as the PPI .	After induction of anesthesia and before surgical incision

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference Between Intraoperative Pupillary Pain Index (PPI) and Postoperative Numerical Pain Scale (NRS)	PPI: The PPI mode applies a standardized, incremental transcutaneous electrical stimulation (100 Hz, 10-60mA, with 1-s intervals) that progressively increases in intensity until a pupil dilation of >13% is observed. The degree of reflex dilation is quantified on a scale of 1 (very deep analgesia) to 9 (very light analgesia) and referred to as the PPI.; NRS: the nursing staff in the post-anesthesia care unit asked the patient to rate their pain at the surgical site using the NRS, with a range of 0(no pain)-10(most severe pain).	From emergency of anesthesia to early Post-anesthesia period

Collaborators and Investigators

• Sponsor: Tri-Service General Hospital
• Investigators: Principal Investigator: Yeh Chun-chang, M.D., Department of Anesthesiology, Tri-Service General Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 27, 2022
• Primary Completion (Actual): August 17, 2023
• Study Completion (Actual): August 31, 2023

Study Registration Dates

• First Submitted: October 18, 2022
• First Submitted That Met QC Criteria: October 18, 2022
• First Posted (Actual): October 21, 2022

Study Record Updates

• Last Update Posted (Estimated): May 3, 2024
• Last Update Submitted That Met QC Criteria: May 1, 2024
• Last Verified: May 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Wounds and Injuries; Joint Diseases; Musculoskeletal Diseases; Shoulder Injuries; Shoulder Impingement Syndrome
• Other Study ID Numbers: C202205095

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