Article

Propofol: Relation between brain concentrations, electroencephalogram, middle cerebral artery blood flow velocity and cerebral oxygen extraction during induction of anesthesia

Department of Anaesthesia and Intensive Care, Royal Adelaide Hospital, Adelaide University, North Terrace, Adelaide, South Australia 5000, Australia.
Anesthesiology (Impact Factor: 6.17). 01/2003; 97(6):1363-70. DOI: 10.1097/00000542-200212000-00006
Source: PubMed

ABSTRACT The potential benefit of propofol dose regimens that use physiologic pharmacokinetic modeling to target the brain has been demonstrated in animals, but no data are available on the rate of propofol distribution to the brain in humans. This study measured the brain uptake of propofol in humans and the simultaneous effects on electroencephalography, cerebral blood flow velocity (V(mca)), and cerebral oxygen extraction.
Seven subjects had arterial and jugular bulb catheters placed before induction. Electroencephalography and V(mca) were recorded during induction with propofol while blood samples were taken from both catheters for later propofol analysis. Brain uptake of propofol was calculated using mass balance principles, with effect compartment modeling used to quantitate the rate of uptake.
Bispectral index (electroencephalogram) values decreased to a minimum value of approximately 4 at around 7 min from the onset of propofol administration and then slowly recovered. This was accompanied by decreases in V(mca), reaching a minimum value of approximately 40% of baseline. Cerebral oxygen extraction did not change, suggesting parallel changes in cerebral metabolism. There was slow equilibrium of propofol between the blood and the brain (t(1/2keo) of 6.5 min), with a close relation between brain concentrations and bispectral index, although with considerable interpatient variability. The majority of the decreases in V(mca), and presumably cerebral metabolism, corresponded with bispectral index values reaching 40-50 and the onset of burst suppression.
Description of brain distribution of propofol will allow development of physiologic pharmacokinetic models for propofol and evaluation of dose regimens that target the brain.

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    02/2013; 7(1):75-79. DOI:10.4103/1658-354X.109819
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    • "Due to the fast onset and recovery following administration, repeated neurologic examinations are easy to assess such as a child with sickle cell disease who comes in with altered mental status due to a stroke. Propofol also has anticonvulsant properties and reduces ICP which can be advantageous in sedating a patient with epilepsy or a patient with concerns for obstructive hydrocephalus due to a malfunctioning ventriculoperitoneal shunt to obtain diagnostic neuroradiologic imaging [44–46]. While there have been cases of propofol providing adequate sedation and successfully treating intracranial hypertension [47, 48], several pediatric traumatic brain injury case reports have reported metabolic acidosis and death in patients on prolonged (24 hrs) continuous infusion of propofol [49–53]. "
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    • "Intravenous and inhalational anesthetics have differing effects on cerebral hemodynamics. Inhalational anesthetics cause some vasodilation, whereas intravenous anesthetics do not [1]–[5]. In addition, general anesthetics suppress the activity of brain glucose metabolism in animals and humans in a dose-dependent manner, and administration of a number of anesthetics suppress glucose utilization in the brain [6]–[8]. "
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