Study Results Indicate Brain Wave Monitors
do not Prevent Anesthesia Awareness
esearch presented at the Annual Meeting of the American Patients who experience awareness may develop long-term psycho-
R Society of Anesthesiologists did not find that brain wave moni-
tors are superior to traditional, readily available anesthesia
monitoring methods for preventing long-term psychological symp-
logical consequences including recurring nightmares, anxiety, and
flashbacks. Some may even develop post-traumatic stress disorder.
Postoperative interviews were conducted with six of the patients
toms related to the experience of anesthesia awareness. with awareness experiences between 18 months and two years after
Researchers discussed sub-study findings of the B-Unaware trial, their surgery. Four of the patients contacted reported lucid memories
conducted at Washington University in St. Louis to determine of the procedures consistent with their original reports, but did not
whether a patient monitoring protocol using the BIS monitor was report negative repercussions.
more effective in preventing anesthesia awareness than a simple Two patients reported having negative psychological impact to
protocol based on routine measurement of exhaled anesthetic gas. their daily lives as a result of their awareness experience. Both
“Out of 2,000 patients involved in the B-Unaware trial, we found (patients) were part of the BIS protocol during the B-Unaware trial
that four patients experienced definite awareness and five patients and reported symptoms included avoidance behavior, recurrent
experienced possible awareness. Of those patients, six were part of nightmares, social debility, and depression. Both patients have sought
the BIS protocol, suggesting that the BIS protocol was not superior in counseling to help cope with their symptoms.
this study in preventing cases of awareness,” said Michael Avidan, “The follow-up interviews conducted as a part of this sub-study
MD, associate professor of anesthesiology and surgery at Washington found that long-term psychological symptoms were not prevented
University in St. Louis. by the BIS protocol,” Avidan concluded. “Similar to previous study
While the BIS protocol did not prevent all cases of awareness, findings, we found that the majority of anesthesia awareness episodes
researchers hypothesized that the BIS monitor