Does depth of anesthesia monitoring improve postoperative outcomes?

Devices using the electroencephalogram to estimate anesthetic depth have been available since 1996. Despite the use of these monitors for over a decade, there is little agreement among clinicians about the need for or value of depth of anesthesia monitoring. Since the majority of the studies evaluating the impact of depth of anesthesia monitoring on postoperative outcomes have utilized the bispectral index (BIS Covidian), this manuscript will focus on studies with this device. This review will evaluate the evidence that BIS monitoring can improve long-term outcomes.

BIS-guided anesthesia can reduce the incidence of awareness with recall in high-risk patients, but a recent study found that anesthetic management directed by an end-tidal anesthetic-agent concentration protocol is equally effective, and probably less expensive. Deep anesthesia (BIS < 45) during the intraoperative period is associated with increased postoperative mortality, but this relationship may be an epiphenomenon rather than causal.

There is growing concern that anesthetic management and even specific anesthetic agents may worsen outcomes in high-risk patients. There is, however, no conclusive evidence that depth of anesthesia monitors can improve outcomes and no evidenced-based reasons for anesthesia providers to change their current practice.