Effects of Dexmedetomidine on Intraocular Pressure During Scheduled Spine Surgeries

Study Overview
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Brief Summary
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The aim of this study is to examine the effects of intraoperative systemic use of dexmedetomidine on the intraocular pressure (IOP) in patients undergoing spine surgeries in a prone position under general anesthesia.

Detailed Description
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The study is a Prospective, Randomized, Placebo -controlled, Double-Blinded clinical trial Adult patients with an ASA physical status of class I, II or III who are scheduled for an elective spine surgery in prone position under general anesthesia will be included in the study. The patients will be randomized with closed envelope manner into two groups: the group of dexmedetomidine and the group of normal saline. In the dexmedetomidine group (DEX group), bolus dose 1,0 μg/kg of dexmedetomidine will be administered in 10min before induction to anesthesia and 0,4-0,8 μg/kg/h of dexmedetomidine will be infused continuously until the end of the surgery. In the saline group (placebo group), the same volume of saline will be administered in an identical way. All study medication will be prepared by an independent anesthesiologist who is not associated in the study (who will hold the randomization codes until the end of the study). All patients will receive the same type of anaesthesia (TIVA with propofol) and postoperative analgesia including paracetamol 1gr iv (4 times/day) and continuous wound infiltration with ropivacaine 0.2% 5ml/h for 48 postoperative hours. Basic monitoring for the study includes: ECG, Invasive and noninvasive blood pressure, Heart Rate, EtCO2, SpO2, Cardiac Output (CO), Stroke Volume (SV), Stroke Volume Variation (SVV), Patient State index (PSi), IOP, Urine output. Measurements The measurement of IOP will be conducted in both eyes with Icare PRO tonometer by an ophthalmologist who will not know in which group the patient is in the below predefined time points: T1: before administration of the study drug T2: after administration of the bolus dose of the study drug T3: after tracheal intubation T4: just before prone position T5: just after prone position T6: 30min after T5 T7: 60min after T6 T8: 120min after T7 T9: 180min after T8 T10: at the end of the surgery and the patient in supine position At the time of each tonometer reading the following data set is collected: MAP, heart rate, EtCO2, SpO2, CO, SV, SVV, urine output, Psi, IOP. Moreover OPP will be calculated as MAP minus IOP.

Official Title
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Effects of Systemic Administration of Dexmedetomidine on Intraocular Pressure During Scheduled Spine Surgeries in a Prone Position. Prospective, Randomized, Double-blinded Study.

Conditions
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Intraocular Pressure

Intervention / Treatment
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* Drug: Dexmedetomidine
* Other: Normal Saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients undergoing scheduled spine surgery performed in prone position under general anaesthesia Exclusion Criteria: Patients who refuse to be a part of the study Patients with previous eye surgery Preexisting eye disease (e.g glaucoma) Allergy to the study drug or any drug which is in the trial Preoperative unstable hemodynamics

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Prospective, Randomized, Placebo -controlled, Double-Blinded clinical trial
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: DEX group<br>Dexmedetomidine given at a bolus dose of 1,0 μg/kg 10min before induction of anesthesia and then after as a continuous infusion 0,4-0,8 μg/kg/h until the end of the surgery. | Drug: Dexmedetomidine<br>* Administration<br>* Other names: Dexmed;|
| Placebo Comparator: Placebo group<br>Normal saline given as a bolus dose 10min before induction of anesthesia and then after as a continuous infusion until the end of the surgery. | Other: Normal Saline<br>* Administration<br>* Other names: Saline;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intraocular pressure (IOP) | The measurement of IOP will be conducted in both eyes with Icare PRO tonometer by an ophthalmologist at predefined time points | Up to 15 minutes after the end of operation |