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[Electroencephalographic and hemodynamic monitoring at various desflurane concentrations]
1Servicio de Anestesiología y Reanimación, Ciudad Sanitaria y Universitaria de Bellvitge, L'Hospitalet de Llobregat, Barcelona.
Objectives:
To assess the electroencephalographic patterns and hemodynamic changes produced by desflurane at 0.5, 1 and 1.5 MAC.
Material And Methods:
Twenty-four patients undergoing gynecological surgery under general anesthesia were enrolled prospectively. We monitored electroencephalographic (EEG) patterns and hemodynamic parameters as well as inspired and expired desflurane fractions. Anesthetic induction was with 2 mg/kg of propofol, 2 to 3 mg/kg of fentanyl and 0.1 mg/kg vecuronium. Spectral edge frequency (SEF90) and the EEG delta ratio were recorded along with mean systolic and diastolic pressures, heart rate, oxygen saturation and expired CO2 fraction during induction, intubation, 5 min after intubation and at 0.5, 1 and 1.5 MAC during weaning from anesthesia and extubation.
Results:
Blood pressure fell significantly at 1.5 MAC and increased when anesthesia was withdrawn; heart rate did not change significantly. SEF90 and the delta ratio changed, however, at each phase. SEF90 fell notably at the moment of induction but gradually increased, rising upon intubation, 5 min later, at 0.5 MAC and upon withdrawal of anesthesia. A significant decrease in SEF90 appeared when 1.5 MAC was reached, related to achievement of a deeper plane of anesthesia.
Conclusions:
Automated EEG processing can provide a good measure of depth of anesthesia, as it reflects significant changes related to level of anesthesia at each phase. These differences are not always observable with routine monitoring of hemodynamic parameters.