Effect of ephedrine and phenylephrine on brain oxygenation and microcirculation in anaesthetised patients with cerebral tumours: study protocol for a randomised controlled trial.

Autor:	Koch KU; Department of Anesthesiology and Intensive Care-North, Section of Neuroanesthesia, Aarhus University Hospital, Aarhus, Denmark., Tietze A; Department of Neuroradiology and Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark.; Institute of Neuroradiology, Charite Universitatsmedizin, Berlin, Germany., Aanerud J; Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark., Öettingen GV; Department of Neurosurgery, Aarhus University Hospital, Aarhus, Denmark., Juul N; Department of Anesthesiology and Intensive Care-North, Section of Neuroanesthesia, Aarhus University Hospital, Aarhus, Denmark., Sørensen JCH; Department of Neurosurgery, Aarhus University Hospital, Aarhus, Denmark., Nikolajsen L; Department of Anesthesiology and Intensive Care-North, Section of Neuroanesthesia, Aarhus University Hospital, Aarhus, Denmark., Østergaard L; Department of Neuroradiology and Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark., Rasmussen M; Department of Anesthesiology and Intensive Care-North, Section of Neuroanesthesia, Aarhus University Hospital, Aarhus, Denmark.
Jazyk:	angličtina
Zdroj:	BMJ open [BMJ Open] 2017 Nov 17; Vol. 7 (11), pp. e018560. Date of Electronic Publication: 2017 Nov 17.
DOI:	10.1136/bmjopen-2017-018560
Abstrakt:	Introduction: During brain tumour surgery, vasopressor drugs are commonly administered to increase mean arterial blood pressure with the aim of maintaining sufficient cerebral perfusion pressure. Studies of the commonly used vasopressors show that brain oxygen saturation is reduced after phenylephrine administration, but unaltered by ephedrine administration. These findings may be explained by different effects of phenylephrine and ephedrine on the cerebral microcirculation, in particular the capillary transit-time heterogeneity, which determines oxygen extraction efficacy. We hypothesised that phenylephrine is associated with an increase in capillary transit-time heterogeneity and a reduction in cerebral metabolic rate of oxygen compared with ephedrine. Using MRI and positron emission tomography (PET) as measurements in anaesthetised patients with brain tumours, this study will examine whether phenylephrine administration elevates capillary transit-time heterogeneity more than ephedrine, thereby reducing brain oxygenation. Methods and Analysis: This is a double-blind, randomised clinical trial including 48 patients scheduled for surgical brain tumour removal. Prior to imaging and surgery, anaesthetised patients will be randomised to receive either phenylephrine or ephedrine infusion until mean arterial blood pressure increases to above 60 mm Hg or 20% above baseline. Twenty-four patients were allocated to MRI and another 24 patients to PET examination. MRI measurements include cerebral blood flow, capillary transit-time heterogeneity, cerebral blood volume, blood mean transit time, and calculated oxygen extraction fraction and cerebral metabolic rate of oxygen for negligible tissue oxygen extraction. PET measurements include cerebral metabolic rate of oxygen, cerebral blood flow and oxygen extraction fraction. Surgery is initiated after MRI/PET measurements and subdural intracranial pressure is measured. Ethics and Dissemination: This study was approved by the Central Denmark Region Committee on Health Research Ethics (12 June 2015; 1-10-72-116-15). Results will be disseminated via peer-reviewed publication and presentation at international conferences. Trial Registration Number: NCT02713087; Pre-results. 2015-001359-60; Pre-results. Competing Interests: Competing interests: None declared. (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)
Databáze:	MEDLINE
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