The Effects of Dexmedetomidine and Propofol on Cerebral Blood Flow and Brain Oxygenation During Deep Brain Stimulation

Study Overview
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Brief Summary
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The investigators will evaluate the effects of dexmedetomidine and propofol on cerebral blood flow and brain oxygenation during Deep Brain Stimulation (DBS) surgery. Specifically, the investigators will test the hypothesis that dexmedetomidine is non-inferior to propofol for cerebral blood flow as measured by transcranial Doppler and brain oxygenation as measured by near-infrared spectroscopy.

Conditions
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Intracranial Neurosurgery

Intervention / Treatment
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* Drug: dexmedetomidine
* Drug: propofol


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA I-III. Scheduled for DBS. Exclusion Criteria: History of dystonia. Severe heart failure with ejection fraction less than 30%. History of obstructive sleep apnea. History of renal failure with creatinine level > 2 mg/dl. Allergies to α-2 agonists and propofol. Current use of α-2 agonist medications such as clonidine.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: propofol<br>Subjects will be sedated with propofol. | Drug: propofol<br>* Patients assigned to propofol will be given an infusion dose of 50-75 µ/kg/min which will be titrated to the patient's response<br>|
| Active Comparator: dexmedetomidine<br>Subjects will be sedated with dexmedetomidine. | Drug: dexmedetomidine<br>* Patients assigned to dexmedetomidine will be given a mg/kg bolus over 10-20 minutes; subsequently, an infusion will be titrated to between 0.4-0.6 mcg/kg/hr to maintain an adequate level of sedation during the procedure.<br>* Other names: Precedex;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cerebral Blood Flow | Cerebral blood flow was the average of right and left carotid velocities recorded by transcranial Doppler. | For patients randomized to dexmedetomidine: at the first peak of study drug (i.e., at peak dose of study drug during first infusion period); for patients randomized to propofol: when infusion of propofol stopped. | 
| Brain Oxygen | Brain oxygenation values were estimated by near-infrared spectroscopy and brain oxygenation was averaged across the first and second study drug infusion periods. | during first (10-20 minutes) and second (throughout the procedure) study drug infusion periods | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cerebral Blood Flow | The investigator will test the hypothesis that dexmedetomidine is non-inferior to propofol for cerebral blood flow as measured by transcranial Doppler and brain oxygenation as measured by near-infrared spectroscopy. | after procedure, in post anesthesia care unit (PACU) | 
| Alertness/Sedation | Modified observer's assessment of alertness /sedation (OAA/S) scale which ranges from 0 to 5 (0 = does not respond to noxious stimuli and 5 = responds to name spoken in normal tone) | at the first peak during DBS surgery | 
| Pulsatility Index | Pulsatility index is a measure of the variability of blood velocity in a vessel, and was calculated as the difference between the peak systolic and minimum diastolic velocities divided by the mean velocity during the cardiac cycle. | at the first peak during DBS surgery | 
| Cerebral Perfusion Pressure |  | at the first peak during DBS surgery | 
| Number of Hypertensive Episodes | The number of hypertensive episodes during Deep Brain Stimulation (DBS) surgery. | During DBS surgery | 
| Number of Apneic Episodes. | The number of antihypertensive interventions during Deep Brain Stimulation (DBS) surgery. | during DBS surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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dexmedetomidine, propofol, cerebral blood flow, brain oxygenation