Awareness during anesthesia: a problem without solutions?

Awareness during anesthesia has been the subject of much research and commentary in recent years. In this article, we review the recent publications in the area of anesthesia awareness and attempt to answer the question: Is awareness a problem without solutions? The incidence of awareness has been reported in benchmark studies to be about 0.1%, but two recent studies in Spain and China have reported incidences of awareness of 1% and 0.4%, respectively. Recent studies have confirmed that awareness is more common in women undergoing cesarean sections (0.26%) and in children (0.5-1%). There are very few trials that provide strong evidence for awareness prevention strategies. The best current evidence from one randomized trial suggests that bispectral index monitoring identifies the presence and reduces the incidence of awareness in high-risk patients. More trials are needed and two large ongoing trials are exploring the value of monitoring end-tidal gas concentrations and maintaining adequate age-adjusted values during surgery as an alternative method to prevent awareness.