Effect-site target-controlled infusion of propofol: comparison of Schnider and modified Marsh models

Chang, Ri Na; Baik, Hee Jung; Kim, Dong Yeon; Lee, Guie Yong; Chung, Rack Kyung; Lee, Heeseung

Abstract

BACKGROUND
We investigated effect-site concentrations of propofol, changes in blood pressure and heart rate, time to loss of consciousness, time to loss of eyelid reflex and awakening time during anesthesia using effect-site target-controlled infusion, to compare the differences between Schnider and modified Marsh model.
METHODS
Forty American Society of Anesthesiologists (ASA) physical status I or II patients between the ages of 18 and 55 years old and who were scheduled for elective surgery under general anesthesia were enrolled in this study. The patients were randomized into two groups: one group using modified Marsh model (Group 1) and the other group using Schnider model (Group 2). Effect-site concentrations of propofol, blood pressure, heart rate and BIS at each anesthetic stage were recorded. Time to loss of consciousness, time to loss of eyelid reflex and awakening time were measured.
RESULTS
Group 1 showed shorter time to loss of consciousness and eyelid reflex at the lower effect-site concentration of propofol than Group 2 (P < 0.05). The effect-site concentrations of Group 1 were higher than those of Group 2 at eye opening and extubation (P < 0.05).
CONCLUSIONS
Induction of anesthesia is achieved at lower effect-site concentration of propofol and more rapidly in the modified Marsh model than in the Schnider model. However the effect-site concentrations of propofol for awakening are higher in the modified Marsh model than in the Schnider model.