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

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

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.

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.

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,