Vasopressor Effects in Anesthetized Patients

Project title: Influence of Vasopressors on Brain Oxygenation and Microcirculation in Anesthetized Patients with Cerebral Tumors Sponsor-investigator: Klaus Ulrik Koch M.D. Sponsor: Department of Anesthesia Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark Objective: To investigate whether phenylephrine and ephedrine causes different alterations in microcirculation and oxygenation, as measured with MRI and PET, in anesthetized patients with brain tumors. Using MRI and PET, the study will assess whether there is a difference in deoxyhemoglobin concentration (Bold signal), CTTH, cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) between ephedrine and phenylephrine Method: Double blinded controlled randomized clinical trial. Either phenylephrine or ephedrine are infused intravenously under general anesthesia. MRI is performed in 20 patients before and after infusion. PET/CT is performed in 20 patients before and after infusion. BIS and NIRS monitoring will be used in either scanner. After scanning patients are transported to the operating theatre and the craniotomy is performed. After removal of the bone flap subdural ICP is measured and recorded. MRI to analyze CBF, CTH, max.CMRO2, maxOEF, CBV and grey-scale ADC before and after ephedrine and phenylephrine. PET/CT to analyze CBF and CMRO2 before and after ephedrine and phenylephrine and calculation of OEF. During each PET/CT scan session oxygen saturation and hemoglobin concentration is measured. Data from the proposed studies will add substantial new knowledge to the investigators current understanding of the effects of vasopressors on cerebral circulation. This information will aid the neuroanesthesiologist, neurointensivist and the neurosurgeon in the choice of the optimal method to manage cerebral perfusion pressure during craniotomy for brain tumor.

Sex

All

Minimum age

18 Years

Maximum age

75 Years

Inclusion Criteria:

* Patients scheduled for supine-positioned elective craniotomy for supratentorial malignant and non-malignant brain tumors 3 cm or larger (measured as the largest diameter in any plane on MR images)
* ASA (American Society of Anesthesiologist) status 1-3 (27)
* Written informed consent from participating patients

Exclusion Criteria:

* Age younger than 18 yrs. or older than 75 yrs.
* Pregnancy or nursing (negative pregnancy blood test)
* History of allergic reactions to phenylephrine or ephedrine
* eGFR \< 60ml/min/1.73m2

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