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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

Status
Completed
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT05590767
Enrollment
40
Registered
2022-10-21
Start date
2022-10-27
Completion date
2023-08-31
Last updated
2024-05-03

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Shoulder Impingement, Surgery

Brief summary

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?

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?

Interventions

PROCEDUREPatients scheduled to undergo shoulder rotators repair surgery

Patients scheduled to undergo shoulder rotators repair surgery, and received combined general anesthesia and interscalene block

Sponsors

Tri-Service General Hospital
Lead SponsorOTHER

Study design

Observational model
CASE_ONLY
Time perspective
PROSPECTIVE

Eligibility

Sex/Gender
ALL
Age
20 Years to 85 Years
Healthy volunteers
No

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

Design outcomes

Primary

MeasureTime frameDescription
Pupillary Pain Index (PPI )After induction of anesthesia and before surgical incisionThe 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 .

Secondary

MeasureTime frameDescription
Difference Between Intraoperative Pupillary Pain Index (PPI) and Postoperative Numerical Pain Scale (NRS)From emergency of anesthesia to early Post-anesthesia period1. 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. 2. 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).

Countries

Taiwan

Participant flow

Participants by arm

ArmCount
Shoulder Rotators Repair
Patients scheduled to undergo shoulder rotators repair surgery Patients scheduled to undergo shoulder rotators repair surgery: Patients scheduled to undergo shoulder rotators repair surgery, and received combined general anesthesia and interscalene block
34
Total34

Withdrawals & dropouts

PeriodReasonFG000
Overall Studyinterscalene brachial block not performed1
Overall StudyProtocol Violation1
Overall Studysurgery canceled1

Baseline characteristics

CharacteristicShoulder Rotators Repair
Age, Continuous62 years old
STANDARD_DEVIATION 11
Body Mass Index (BMI)24.1 kg/m^2
STANDARD_DEVIATION 2.7
Race and Ethnicity Not Collected— Participants
Region of Enrollment
Taiwan
34 participants
Sex: Female, Male
Female
21 Participants
Sex: Female, Male
Male
13 Participants

Adverse events

Event typeEG000
affected / at risk
deaths
Total, all-cause mortality
0 / 34
other
Total, other adverse events
0 / 34
serious
Total, serious adverse events
0 / 34

Outcome results

Primary

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 .

Time frame: After induction of anesthesia and before surgical incision

Population: 40 patients scheduled for rotator cuff surgery were recruited for this study. Of these, three did not follow the study protocol: one had canceled surgery, one did not undergo ISB, and in one case, sevoflurane was not used as the main anesthetic. For the remaining 37 patients, Three patients did not report a loss of subjective cold/pinprick sensation in the C5 and C6 dermatomes, indicating an unsuccessful block. Therefore, 34 patients were included in the final analysis.

ArmMeasureGroupValue (MEAN)Dispersion
Shoulder Rotators RepairPupillary Pain Index (PPI )ISB side1.8 score on a scaleStandard Deviation 0.2
Shoulder Rotators RepairPupillary Pain Index (PPI )Control side6.6 score on a scaleStandard Deviation 0.3
Secondary

Difference Between Intraoperative Pupillary Pain Index (PPI) and Postoperative Numerical Pain Scale (NRS)

1. 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. 2. 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).

Time frame: From emergency of anesthesia to early Post-anesthesia period

Population: 40 patients scheduled for rotator cuff surgery were recruited for this study. Of these, three did not follow the study protocol: one had canceled surgery, one did not undergo ISB, and in one case, sevoflurane was not used as the main anesthetic. For the remaining 37 patients, Three patients did not report a loss of subjective cold/pinprick sensation in the C5 and C6 dermatomes, indicating an unsuccessful block. Therefore, 34 patients were included in the final analysis.

ArmMeasureGroupValue (MEAN)Dispersion
Shoulder Rotators RepairDifference Between Intraoperative Pupillary Pain Index (PPI) and Postoperative Numerical Pain Scale (NRS)intraoperative PPI1.5 score on a scaleStandard Deviation 0.2
Shoulder Rotators RepairDifference Between Intraoperative Pupillary Pain Index (PPI) and Postoperative Numerical Pain Scale (NRS)postoperative NRS1.7 score on a scaleStandard Deviation 1.3

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026