Effect of Propofol and Clonidine on Cerebral Blood Flow Velocity and Carbon Dioxide Reactivity in the Middle Cerebral Artery
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Date
2004
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Abstract
This study was designed to evaluate the effects of propofol alone and propofol-clonidine combination on human middle cerebral artery blood flow velocity (Vmca) and cerebrovascular carbon dioxide (CO2) response by using transcranial Doppler ultrasonography. Mean Vmca in response to changes in arterial partial pressure of CO2 (PaCO2) was determined under the following conditions: awake (group 1), propofol anesthesia (group 2), and combined propofol-clonidine anesthesia (group 3). Normocapnic, hypercapnic, and hypocapnic values of heart rate, mean arterial pressure, partial end-tidal CO2 pressure, PaCO2, and Vmca were obtained. The mean Vmca in groups 2 and 3 was significantly lower than that in group 1 at each level of PaCO2. The calculated Vmca at each level of PaCO 2 was not different between groups 2 and 3. There was a correlation between PaCO2 and Vmca in all groups, but in the anesthetized groups the effect of PaCO2 on Vmca was attenuated. The present data demonstrated that clonidine-propofol does not change CO2 reactivity compared with propofol alone, but both anesthetics attenuate cerebral blood flow compared with awake controls.
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Keywords
Adrenergic alpha-Agonists , Adult , Analysis of Variance , Anesthetics, Combined , Anesthetics, Intravenous , Blood Flow Velocity , Blood Pressure , Carbon Dioxide , Cerebrovascular Circulation , Clonidine , Female , Heart Rate , Humans , Male , Middle Cerebral Artery , Partial Pressure , Propofol , Ultrasonography, Doppler, Transcranial , carbon dioxide , clonidine , propofol , rocuronium , adult , anesthesia , anesthesia induction , arterial carbon dioxide tension , article , blood flow velocity , blood vessel reactivity , brain blood flow , calculation , clinical article , controlled study , correlation analysis , Doppler echography , drug effect , end tidal carbon dioxide tension , female , heart rate , human , hypercapnia , hypocapnia , male , mean arterial pressure , middle cerebral artery , priority journal , statistical significance , wakefulness