Propofol: relation between brain concentrations, electroencephalogram, middle cerebral artery blood flow velocity, and cerebral oxygen extraction during induction of anesthesia.
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.
- SourceAvailable from: Zeljko Bosnjak[Show abstract] [Hide abstract]
ABSTRACT: Recent studies in various animal models have suggested that anesthetics such as propofol, when administered early in life, can lead to neurotoxicity. These studies have raised significant safety concerns regarding the use of anesthetics in the pediatric population and highlight the need for a better model to study anesthetic-induced neurotoxicity in humans. Human embryonic stem cells are capable of differentiating into any cell type and represent a promising model to study mechanisms governing anesthetic-induced neurotoxicity.Anesthesiology 06/2014; · 6.17 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Comparative study between fast and slow induction of propofol given by target-controlled infusion: expected propofol concentration at the effect site. Randomized controlled trialRevista Brasileira de Anestesiologia 11/2014; 65(2):99. · 0.42 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The sitting position may cause significant hemodynamic instability and cerebral hypoperfusion. We investigated the effects of desflurane and propofol on regional cerebral oxygenation (rSO2) in the sitting position during arthroscopic shoulder surgery. Forty patients undergoing arthroscopic shoulder surgery in the sitting position were randomly allocated to the desflurane group (n = 20) or the propofol group (n = 20). Anesthetic agents were maintained and adjusted with the effect-site concentration of propofol (2-3.5 μg/ml) or desflurane (4-7 vol%) to obtain a bispectral index (BIS) of 40-50. The hemodynamic variables, end-tidal carbon dioxide tension (ETCO2) and rSO2 were measured and evaluated. There were no differences in BIS, hemodynamic variables and ETCO2 between the groups. The rSO2 values in the desflurane group were higher compared to the propofol group at 3, 5, 7 and 9 min after the sitting position (P = 0.031, 0.047, 0.025 and 0.034, respectively). However, it decreased significantly from the baseline values at 3, 5, 7 and 9 min after the sitting position in both groups (P < 0.001). The change in rSO2 across time was not significantly different between the groups (P = 0.183). The incidence of rSO2 <75 % of the baseline values after the sitting position was similar between the groups (0 and 10 % in the desflurane and propofol group, respectively, P = 0.487). When anesthetized patients were raised to the sitting position, desflurane preserved cerebral oxygenation better than propofol at equipotent concentrations in terms of BIS. However, both anesthetics were associated with significant decrease in the rSO2 values during the sitting position.International Journal of Clinical Monitoring and Computing 12/2013; · 1.45 Impact Factor