The Bispectral Index (BIS) is an electroencephalogram-derived measure of anesthetic depth. We have built a combined closed-loop anesthesia system using BIS as the control variable, two proportional-integral-differential control algorithms, a propofol and a remifentanil target-controlled infusion systems as the control actuators. A recent study has shown that such system is able to provide clinically adequate anesthesia. The aim of the present study is to assess the system during rigid bronchoscopy. Two groups of patients are compared: one in which propofol and remifentanil are administered by the anesthesiologist using target-controlled infusion systems, and one in which propofol and remifentanil are administered automatically by the combined closed-loop anesthesia system. In both groups, the goal is to maintain BIS between 40 and 60, the recommended range during anesthesia by the manufacturer. We expect the combined closed-loop anesthesia system group to do similar or better.