MONDAY, Oct. 20 (HealthDay News) -- Surgical patients who experience anesthesia awareness may be at increased risk of long-term psychological symptoms, but use of a Bispectral index guided protocol -- which is developed from a processed electroencephalogram -- does not appear to decrease this risk, according to research presented at the annual meeting of the American Society of Anesthesiologists held Oct. 18 to 22 in Orlando, Fla.
W. Alex Edwards, of Washington University in St. Louis, and colleagues randomly assigned 2,000 patients to receive either a Bispectral index (BIS) or end tidal anesthetic gas (ETAG) guided protocol. They assessed the patients for anesthesia awareness during three intervals after extubation: 0-24 hours, 24-72 hours and 30 days.
The investigators identified four cases of definite and five cases of possible anesthesia awareness, but only six of the cases were available for psychological assessments, which were conducted 18 to 30 months after surgery. The researchers observed long-term psychological symptoms in one definite case and one possible case, both of whom were only willing to discuss the anesthesia awareness experience at the 30-day post-extubation interview.
"The BIS-guided anesthesia protocol did not prevent long-term psychological symptoms associated with anesthesia awareness," the authors conclude. "The patients who had long-term psychological symptoms had BIS values and ETAG concentrations within the target ranges during their awareness episodes. Patients who are traumatized by anesthesia awareness may be reluctant to talk about their experiences in the early postoperative period."
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