Spectral Entropy Monitoring Reduces Anesthetic Dosage for Patients Undergoing Off-Pump Coronary Artery Bypass Graft Surgery

Abstract

The measurement of the depth of anesthesia is of clinical interest for patients undergoing off-pump coronary artery bypass graft (OPCAB) surgery in order to avoid intraoperative awareness and cardiac depression. Entropy recently was introduced as a monitor of anesthetic depth. This study was conducted to investigate the feasibility of entropy monitoring during the conduct of OPCAB surgery and to find out whether it reduced the anesthetic dosage for patients undergoing OPCAB surgery. A prospective, randomized, single-blind, controlled study. A teaching hospital. Seventy patients scheduled for OPCAB surgery were randomized to receive propofol-sufentanil anesthesia either with the entropy values visible (the entropy group, n = 35) or without the entropy values visible (the control group, n = 35). In the entropy group, propofol and sufentanil infusion rates were titrated to maintain a state entropy (SE) value of 45 to 55 and a response entropy (RE)-SE difference below 10 U. In the control group, patients were anesthetized to keep the heart rate and blood pressure within 25% of the baseline values. The course of surgery, the consumption of anesthetics, and intraoperative recall were recorded. Plasma levels of adrenocorticotropic hormone (ACTH) and cortisol were measured. The average SE during anesthesia was 50 ± 5 in the entropy group; the entropy values were lower in the control group (p < 0.05). Compared with the control group, propofol and sufentanil consumption were significantly less in the entropy group, which shortened the time to tracheal extubation (p < 0.05). Significantly, patients in the control group needed more phenylephrine to maintain arterial pressure than patients in the entropy group (p < 0.05). ACTH and cortisol release were prevented completely, and there was no intraoperative recall reported in the 2 groups. Entropy monitoring reduced propofol and sufentanil dosage for patients undergoing OPCAB surgery.