Comparison of the Effect-site keOs of Propofol for Blood Pressure and EEG Bispectral Index in Elderly and Younger Patients

Abstract

The effect of propofol on BIS occurs more rapidly than its effect on SBP. Age has no effect on the rate of BIS reduction with increasing propofol concentration, whereas with increasing age, SBP decreases to a greater degree but more slowly.

Cardiovascular changes after achieving constant effect site concentration of propofol*

“…They attributed this to the associated reduction in left ventricular performance as measured by the ratio of ventricular contractility to arterial properties (end systolic elastance and effective arterial elastance). Kazama et al had previously estimated that the effect of propofol on the BIS was quicker than that for systolic pressure [7]. They also showed that this discrepancy was greater for older patients, by up to 7.5 min.…”

“…However, the temporal relationship between effect size and the occurrence of the cardiovascular effects and depth of anaesthesia is unclear. A previous study by Kazama et al [7] showed that, using the Gepts model of propofol pharmacokinetics, the maximal cardiovascular depression (using systolic blood pressure only) would happen 8 min after peak plasma concentrations of propofol.Ethically, it is difficult to study the effects of drugs on cardiovascular parameters in healthy individuals using invasive monitoring. Transthoracic electrical bioimpedance estimates cardiac output by measuring non-invasive changes in the resistance to a small current applied across the patient's thorax over time during the cardiac cycle.…”

“…However, the temporal relationship between effect size and the occurrence of the cardiovascular effects and depth of anaesthesia is unclear. A previous study by Kazama et al [7] showed that, using the Gepts model of propofol pharmacokinetics, the maximal cardiovascular depression (using systolic blood pressure only) would happen 8 min after peak plasma concentrations of propofol.…”

Closed-Loop Control of Anaesthetic Effect

“…Currently, the techniques that have been considered more efficient for this are based in the processing of the patient electroencephalogram (EEG), (Kazama et al, 1999;Struys et al, 2000).…”

Intérêt potentiel du BIS pour détecter une souffrance cérébrale importante

“…4 Plusieurs auteurs se sont attachés à comparer sa sensibilité et sa spécificité avec d'autres moyens de surveillance de l'anesthésie comme les potentiels évoqués auditifs, la variabilité de la fréquence cardiaque, 5-8 la surveillance de l'EEG, la surveillance hémodynamique et clinique. 9,10 Différents types d'appareils ou d'électrodes ont également fait l'objet de travaux afin d'évaluer la pertinence des données délivrées par la mesure du BIS ainsi que la reproductibilité d'un patient à l'autre ou chez un même patient. 1 1 Cependant lors de son utilisation en pratique quotidienne il ressort que même si le BIS permet une éval-uation fiable de l'état de narcose des patients, la profondeur de l'anesthésie n'est pas l'unique source de variation de l'index mesuré.…”