CLINICAL USEFULNESS OF THE BISPECTRAL IN INDEX FOR TITRATING PROPOFOLTARGET EFFECT-SITE CONCENTRATION

The bispectral index, a new processed electroencephalographic paramete r which may give information on depth of anaesthesia, was used in 58 p atients undergoing outpatient gynaecological surgery in order to study if the addition of bispectral index monitoring to standard clinical m onitoring could improve the titration of target propofol concentration when using effect-site target-controlled propofol infusion for sedati on. In Group 1 (rr=30), the bispectral index was recorded but the anae sthetist was unaware of the readings and therefore only classical sign s of depth of anaesthesia were used to guide the anaesthetist in contr olling the effect-site concentration. In Group 2 (n=28), bispectral in dex readings were available to the anaesthetist and effect-site concen tration was adjusted to ensure that bispectral index was maintained be tween 40 and 60. Similar propofol induction and maintenance doses, blo od and effect-site concentrations and mean bispectral index were found in the two groups. A greater percentage of bispectral index readings lying outside the target range (i.e. <40 or >60) and more movement at incision and during maintenance were found in Group 1. There was a tre nd towards more implicit awareness in patients in Group 1. Bispectral index was found to be useful for measuring depth of sedation when usin g propofol target-controlled infusion. Propofol dosage could not be de creased but a more consistent level of sedation could be maintained du e to a more satisfactory titration of target effect-site concentration .