Anaesthesia guidance system can reduce awareness during surgery
NB: Please note that if you are outside North America, the embargo for LANCET press material is 0001 hours UK Time Friday 28 May 2004
An Australian study in this week's issue of THE LANCET highlights how the neuromonitoring of brain patterns of patients during surgery could help guide the use of anaesthesia and reduce the risk of patients becoming aware during surgery-thought to occur in around 0.1-0.2% of patients.
Bispectral index (BIS) monitoring measures the depth of anaesthesia by analysis of brain EEG patterns and produces a score between 0 (deep anaesthesia) and 100 (awake). Scores of 40-60 are suitable for surgical anaesthesia; however, BIS has not previously been assessed in a randomised trial to guide the delivery of anaesthesia in order to reduce awareness during surgery.
Paul Myles from Alfred Hospital, Victoria, Australia, and colleagues randomly allocated around 2500 patients known to be at risk of awareness during surgery to receive either BIS-guided anaesthesia or standard care. Reported awareness was documented independently a few hours, one day, and one month after surgery.
BIS-guided anaesthesia reduced the incidence of awareness during surgery by over 80%; there were only two reported cases of awareness with BIS-guided anaesthesia compared with 11 reports among patients given standard care.
Professor Myles comments: "We have shown that use of BIS monitoring can reduce the incidence of awareness under general anaesthesia in patients at risk, suggesting that greater use of BIS monitoring is warranted in patients at increased risk of awareness undergoing relaxant general anaesthesia".
In an accompanying Commentary (p 1747) Claes Lennmarken from University Hospital, Linkoping, Sweden, concludes: "Myles and colleagues' study is a great leap forward, and hopefully it will also inspire those who have denied the potential of the neuromonitoring technologies to join in the efforts to ensure the sometimes missing component in what was started in 1846-general anaesthesia."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
Published on PsychCentral.com. All rights reserved.