Bispectral index-guided anesthesia in patients undergoing aortocoronary bypass grafting

In this prospective, randomized study, we compared hemodynamics, oxygenation, possible intraoperative awareness, and costs in 62 patients undergoing first-time elective coronary artery bypass grafting at 2 different levels of anesthesia. Depth of anesthesia was assessed with bispectral index (BIS). All patients were anesthetized with sufentanil/midazolam. The dosage of sufentanil/midazolam was adjusted to achieve a BIS level of 45-55 in 32 patients (Group BIS 50), whereas in 30 patients a BIS level of 35-45 was intended (Group BIS 40). Data were obtained at six different time points before, during, and after surgery. All patients were asked about possible intraoperative awareness on the third postoperative day. There were no significant differences of any hemodynamic or oxygenation variables at any time between the two groups. BIS 40 patients received significantly (P < 0.05) more sufentanil (BIS 40, 888 +/- 211 microg; BIS 50, 514 +/- 99 microg) and midazolam (BIS 40, 22.4 +/- 5.6 mg; BIS 50, 16.6 +/- 3.7 mg) than BIS 50 patients. The reduction in anesthetic drugs used saved euro;13.78/US$12.54 per patient (P < 0.05) in Group BIS 50, but one BIS electrode caused additional costs of 19.95 Euros/18.15 US dollars. Time to extubation was not significantly prolonged in Group BIS 40 (BIS 40, 14.3 +/- 4.6 h; BIS 50, 11.8 +/- 3.8 h). There was no explicit memory during anesthesia in either group. BIS-guided reduction of anesthetic medication saved costs and did not increase the risk of intraoperative awareness. However, total costs were increased by monitoring BIS, because of the BIS electrodes.