Effects of Sevoflurane and Propofol on Light Flashed Evoked Pupillometry

Study Overview
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Brief Summary
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This is a study to focus on the feasibility of using a monitor which may signal loss of visual function intraoperatively.

Detailed Description
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The degree of a relative afferent pupillary defect (RAPD) has been correlated with the severity of an eye injury and has been shown to have prognostic significance as an indicator of retinal ischemia. Therefore light flashed evoked pupillometry (LFEP) may serve as a useful indicator of visual function. LFEP's are not known to be sensitive to anesthetics. We will measure LFEP's using different anesthetic techniques to see if there are measurable differences in the latency, amplitude and constriction velocity of the pupillary reflex. Prior to induction of anesthesia, pupillometer readings will be taken in the supine position in both eyes. The patient will be anesthetised using a standard induction technique. For maintenance of anesthesia a remifentanil infusion will be administered and supplemented by either propofol infusion (at 120 and 160 mcg/kg/min)or sevoflurane (at 1.5 and 2.5% end-tidal in random sequence. The patients will receive muscle relaxants as needed. Pupillometry readings will be taken in both eyes after induction, after steady maintenance has been achieved and every 10 minutes for 30 minutes at each drug dose.

Official Title
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The Effects of Sevoflurane and Propofol on Light Flashed Evoked Pupillometry

Conditions
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Blindness

Intervention / Treatment
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* Drug: propofol
* Drug: Sevoflurane


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: planned orthopedic surgery on the lower extremities and positioned on the back Exclusion Criteria: recent bout of conjunctivitis or pink eye condition which inhibits the normal pupillary function of my eye

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 2. Sevoflurane<br>Subjects will receive sevoflurane at 1.5% and 2.5% end tidal after steady state maintenance has been achieved and have pupillometry readings taken and every 10 minutes for 30 minute at each drug dose. | Drug: Sevoflurane<br>* sevoflurane 1.5% and 2.5% end tidal in random sequence<br>* Other names: Sevoflurane at 1.5 and 2.5% end tidal;|
| 1.Propofol<br>1.Subjects will receive propofol infusion and have pupillometry readings taken in both eyes after induction, after steady state maintenance has been achieved and at 30 minutes | Drug: propofol<br>* Propofol infusion 120 and 160 mcg/kg/min in random sequence during the operative procedure<br>* Other names: deprivan;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measure the pupil response using different anesthetic techniques |  | pupillometry measurements will be taken in both eyes after induction of anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Measure the pupil response using different anesthetic techniques |  | When steady maintenance of anesthesia drug is obtained measure pupillometry response at 10 min | 
| Measure the pupil response using different anesthetic techniques |  | When steady maintenance of anesthesia drug is obtaines measure pupillometry response at 20 minutes | 
| Measure the pupil response using different anesthetic technique |  | When steady maintenance of anesthesia drug is obtained measure pu[illometry response at 30 minutes. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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blindness, ischemic optic neuropathy