Effect of Propofol-Dexmedetomidine on Cerebral Oxygenation and Metabolism During Brain Tumor Resection

Study Overview
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Brief Summary
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Despite theoretical benefits of intravenous agents, volatile agents remain popular. In a study comparing desflurane, isoflurane, and sevoflurane in a porcine model of intracranial hypertension, at equipotent doses and normocapnia, cerebral blood flow (CBF) and intra-cranial pressure (ICP) were least with sevoflurane. Propofol is the most commonly used intravenous anesthetic. It has many theoretical advantages by reducing cerebral blood volume (CBV) and ICP and preserving both autoregulation and vascular reactivity. Neurosurgical patients anaesthetized with propofol were found to have lower ICP and higher CPP than those anaesthetized with isoflurane or sevoflurane. The well known pharmacodynamic advantages of intravenous anesthetics may give this group of drugs superior cerebral effects when compared with inhalation anesthetics.

Detailed Description
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The aim of this study is to evaluate the cerebral haemodaynamics and global cerebral oxygenation as well as the systemic haemodaynamic changes using dexmedetomidine, propofol and fentanyl as total intravenous anaesthestics (TIVA) in comparison with sevoflurane - fentanyl anesthesia in brain tumor resection. Indicators of global cerebral oxygenation and haemodynamics will be calculated using jugular bulb and peripheral arterial blood sampling. Induction: propofol, 1.5 - 2 mg/kg. Muscle Relaxants: atracurium, 0.5 mg/kg with induction and 0.1 mg/kg/20min. for maintenance. Cannulation: Arterial cannula: under complete aseptic conditions 20G cannula was inserted into the radial artery of non dominant hand after performing modified Allen's test and local infiltration of 0.5ml xylocaine 2%. Central venous catheter: A suitable central venous catheter will be inserted into Rt subclavian vein under complete aseptic technique, its correct position will be confirmed with chest X-Ray. Jugular bulb catheterization: Under strict sterile technique the right internal jugular vein will be cannulated in a retrograde technique with confirmation of the catheter tip position using X-Ray (C- arm). Puncture site will be at the level of cricoid cartilage behind the anterior border of the sternocleido-mastoid muscle.

Official Title
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Effect of Propofol-Dexmedetomidine Total Intravenous Anaesthesia on Cerebral Oxygenation and Metabolism During Brain Tumor Resection Compared to Sevoflurane Anaesthesia

Conditions
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Brain Tumor, Surgery

Intervention / Treatment
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* Drug: Propofol-Dexmedetomidine group
* Drug: Sevoflurane group


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists physical status III or IV. Patients scheduled for elective brain tumor resection Exclusion Criteria: Morbid obese patients. Severe or uncompensated cardiovascular diseases. Severe or uncompensated renal diseases. Severe or uncompensated hepatic diseases. Severe or uncompensated endocrinal diseases. Pregnancy. Postpartum or lactating females. Allergy to one of the agents used. Severely altered consciousness level. Sitting position during surgery. Prone position during surgery,

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 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: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Propofol-Dexmedetomidine group<br>this group is planned to receive intravenous anaesthesia only | Drug: Propofol-Dexmedetomidine group<br>* Porofol (1.5-2 mg/kg/h) infusion, Dexmedetomidine (0.2-1µg/kg/h) infusion and Fentanyl in repeated doses (50µ) when needed (heart rate or mean arterial blood pressure increase more than 20% of the basal value). Maintenance infusions will start immediately after induction.<br>|
| Active Comparator: Sevoflurane group<br>this group is planned to receive sevoflurane/fentanyl anaesthesia | Drug: Sevoflurane group<br>* Sevoflurane at a concentration of 2-2.5%., Fentanyl in repeated doses (50µ) when needed (heart rate or mean arterial blood pressure increase more than 20% of the basal value).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterio-Jugular oxygen content difference |  | immediately after cannulation (arterial and jugular), every 30 min during surgery and after complete closure of the scalp | 
| Estimated cerebral metabolic rate for O2 (eCMRO2) | eCMRO2=Ca- jO2 x(PaCO2 ∕ 100) Where Ca jO2 is arterio-jugular O2 content difference. PaCO2 is arterial CO2 tension | immediately after cannulation (arterial and jugular), every 30 min during surgery and after complete closure of the scalp | 
| Cerebral Extraction Rate of O2 (CEO2) | Calculated as the differences between arterial and jugular bulb O2 saturations, CEO2 = SaO2 - SjvO2 | immediately after cannulation (arterial and jugular), every 30 min during surgery and after complete closure of the scalp. | 
| Cerebral Blood Flow equivalent (CBFe) | Which is an index of flow metabolism relationship, calculated as a reciprocal of arterio-jugular O2 content difference. CBFe = 1 ∕CaO2-CjvO. | immediately after cannulation (arterial and jugular), every 30 min during surgery and after complete closure of the scalp | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate |  | will be monitored continiously and recorded immediately after intubation, every 30 min during surgery and immediately after closure of the scalp | 
| Blood pressure |  | will be monitored continiously and recorded immediately after intubation, every 30 min during surgery and immediately after closure of the scalp | 
| End-tidal carbon dioxide tension |  | will be monitored continiously and recorded immediately after intubation, every 30 min during surgery and immediately after closure of the scalp | 
| Central venous pressure |  | will be monitored continiously and recorded immediately after intubation, every 30 min during surgery and immediately after closure of the scalp | 
| Postoperative level of sedation | all patients will be evaluated using Ramsay sedation scale | every 5 min for 60 min, after extubation | 
| Time for first analgesic request from extubation |  | for 6 hours after surgery | 
| Total analgesics received |  | for 24 hours after surgery | 
| Intensive care unit stay |  | for 10 days after surgery |