Pupil Dilation and Analgesia Nociception Index

Study Overview
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Brief Summary
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Pain assessment is crucial in clinical practice. Currently, subjective self-report is considered the most appropriate method to evaluate pain. Although several methods to assess pain objectively exist, the lack of a golden standard still remains. This pilot study assesses the changes in pupil dilation (PD) and the analgesia nociception index (ANI) as a measure of pain in healthy, conscious, male volunteers in a highly standardized and individualized environment. Nineteen subjects received three blocks of 4 individualized electrical stimulus intensities, ranging from no to severe pain. Subjects reported their perceived severity of each individual stimulus, enabling the comparison of changes in PD and ANI in relation to both administered stimulus intensities and perceived pain severities. PD and ANI were measured before and after each administration of a stimulus.

Official Title
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Do Pupil Dilation and Analgesia Nociception Index Reflect Pain: a Pilot Study in Healthy, Conscious Volunteers

Conditions
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Pain

Intervention / Treatment
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* Diagnostic Test: Measurement of pupil dilation and analgesia nociception index


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: good health no acute or chronic pain conditions well rested Exclusion Criteria: chronic treatment bad health daily use of analgetics or other medication weekly tobacco use weekly use of recreational drugs more than 10 alcohol consumptions a week

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experiment<br>Individualized painful electrical stimuli, Surpass LT stimulator (EMS Biomedical, Korneuburg, Austria) with a bipolar felt pad electrode Measurement of pupil diameter, Algiscan® (iDMed, Marseille, France) Measurement of Analgesia Nociception Index, PhysioDoloris® (MetroDoloris, Lille, France) | Diagnostic Test: Measurement of pupil dilation and analgesia nociception index<br>* painful electrical stimuli of various intensities were administered to the subjects after which changes in pupil diameter and analgesia nociception index were measured<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pupil dilation in relation to pain | measurement of pupil dilation | 2sec before until 4sec after each painful stimulus | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Analgesia nociception index in relation to pain | measurement of analgesia nociception index | 30sec before until 60sec after each painful stimulus |