Abstract
This study was designed to investigate the impact of the Entropy Module and Bispectral Index (BIS) monitoring on drug consumption and recovery times compared with standard anaesthetic practice in patients undergoing orthopaedic surgery using a combination of regional and general anaesthesia as performed by an experienced anaesthesiologist. We hypothesised that electroencephalogram monitoring would lead to a lower drug consumption as well as shorter recovery times. With institutional review board approval and written informed consent, 90 adult patients undergoing surgery to the upper or lower extremity received regional anaesthesia for post- and intraoperative pain control and were randomised to receive general anaesthesia by propofol/remifentanil infusion controlled either solely by clinical parameters or by targeting Entropy or BIS values of 50. Recovery times and drug consumption were recorded. Data from 79 patients were analysed. Compared with standard practice, patients with Entropy or BIS monitoring showed a similar propofol consumption (standard practice 101 +/- 22 microg/kg/minute, Entropy 106 +/- 24 microg/kg/minute, BIS 104 +/- 20 microg/kg/minute) and showed similar Aldrete scores (10/10) one minute after extubation: 9.1 +/- 0.3, 9.2 +/- 0.6 and 9.3 +/- 0.5, respectively. Time points of extubation were 7.3 +/- 2.9 minutes, 9.2 +/- 3.9 minutes and 6.8 +/- 2.9 minutes, respectively, demonstrating a significant difference between Entropy and BIS (P = 0.023). Compared with standard practice, targeting an Entropy or BIS value of 50 did not result in a reduction of propofol consumption during general anaesthesia combined with regional anaesthesia as performed by an experienced anaesthesiologist in orthopaedic patients.
