PREDICTIVE ACCURACY OF MIDAZOLAM IN ADULT PATIENTS SCHEDULED FOR CORONARY SURGERY

Study Objective: To evaluate the predictive accuracy of midazolam duri ng cardiac anesthesia so as to orient the selection of the most approp iate pharmacokinetic model for use in a computer-assisted continuous-i nfusion system. Design: Retrospective analysis. Setting: Operating roo m at a university hospital. Patients: 66 consecutive middle-aged and e lderly coronary patients scheduled for coronary artery bypass graft (C ABG) surgery. Interventions: Patients were anesthetized using a variab le-rate infusion of alfentanil combined with midazolam in an attempt t o achieve and maintain target concentrations of 100 ng/ml or 500 ng/ml . Measurements and Main Results: A total of 323 arterial blood samples were taken, and serum midazolam concentrations were measured by high performance liquid chromatography. Predicted midazolam concentrations were calculated using 3 selected data sets. Their bias, inaccuracy, an d dispersion were assessed by determining the median performance error , the median absolute performance error (MDAPE), and the 10th and 90th percentiles. Two of the selected data sets of midazolam, with a clear ance lower than 5 ml/kg/min, were very accurate (MDAPE less than 20%) in predicting low or high prebypass concentrations of midazolam in adu lt patients with good left ventricular function. Conclusions: Two of t he 3 pharmacokinetic data sets of midazolam studied may be selected wh en using a computer-assisted infusion system in adult coronary patient s.