Pain Assessment by Pupil Dilation Reflex (PDR) and Pupillary Pain Index (PPI) in Response to Noxious Stimulation in Anesthetized Adults

Study Overview
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Brief Summary
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After conduction a pilot study, pupillary dilation reflex (PDR) is measured in response to nociceptive stimulation perioperatively.

Detailed Description
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An infrared camera of the video pupillometer measures the pupillary dilation reflex (PDR) in response to incremental nociceptive stimuli. The PDR is a robust reflex, even in patients under general anesthesia, and may provide a potential evaluation of the autonomous nociceptive circuit. American Society of Anesthesiologists (ASA) classification I or II patients undergoing elective surgery under general anesthesia are recruited. Enrolled patients perioperative undergo PDR measurement at 2 different standardized times (before and after opioid administration) generated by an inbuilt pupillary pain index (PPI) protocol. PPI, as a surrogate for nociception includes noxious stimulations from 10 up to 60 milli ampere (mA) until pupil dilation is larger than 13% from baseline diameter. Therefore, no inappropriate high stimulation is executed.

Official Title
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Pain Assessment by Pupil Dilation Reflex (PDR) and Pupillary Pain Index (PPI) in Response to Noxious Stimulation in Anesthetized Adults

Conditions
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Nociceptive Pain, Monitoring, Intraoperative

Intervention / Treatment
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* Procedure: PDR measurement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Scheduled abdominal or gynecological surgery ASA I-II Exclusion Criteria: History of eye deformity, invasive ophthalmologic surgery Known cranial nerve(s) deficit Infection of the eye Predicted difficult airway management (DAF Guidelines) Chronic opioid use (>3 months) Ongoing treatment with beta-blockers, dopamine antagonists, topical atropine Preoperatively administrated benzodiazepins or antiemetics

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

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: PDR measurement<br>Two measurements of PDR perioperatively before and after opioid administration | Procedure: PDR measurement<br>* PDR measurement at two standardized times perioperatively: : anesthetized subject by propofol sedation until sedation depth monitor NeuroSense® (NeuroWave Systems Inc, Cleveland, OH) between 40-50 : administration of remifentanil via effect site target concentration (Minto-model) at 5 ng/ml, in the absence of adjustments in sedation depth<br>* Other names: PPI assessment;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stimulation Intensity | Necessary stimulation intensity to dilate the pupil more than 13% | During perioperative period | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pupillary Pain Index score | Device specific PPI score defined in accordance to stimulation intensity necessary for pupil dilation more than 13% | During perioperative period | 
| Systolic blood pressure | Hypertension as a common used parameter for perioperative nociceptive assessment | During PDR measurements | 
| Heart rate | Tachycardia as a common used parameter for perioperative nociceptive assessment | During PDR measurements |