[The determination of an effective therapeutic infusion rate for intravenous anesthetics using feedback-controlled dosages]

Abstract

The determination of MAC values (minimum alveolar concentrations) for inhalation anesthetics and, correspondingly, of MIR values (minimum infusion rates) for i.v. anesthetics necessarily requires the use of therapeutically ineffective doses so that reactions to skin incision can be observed. EEG feedback-controlled dosing systems for i.v. anesthetics make it possible to determine dose requirement curves, allowing the definition of effective therapeutic infusion rates (ETI). During total i.v. anesthesia in 11 patients treated with fentanyl the mean effective infusion rate for methohexitone was found to be 4.68 +/- 1.39 mg/min, while for propofol the mean ETI in 11 volunteers was determined at 9.90 +/- 2.46 mg/min. The implications of feedback-controlled dosing systems for the study of clinico-pharmacologic problems in anesthesia are discussed.