A widely-used device that employs brainwaves to help doctors prevent patients from waking up during surgery is no more effective than an older, far less costly technique, according to a recent study of nearly 2,000 patients. The study showed the BIS device, made by Aspect Medical Systems Inc., did not help doctors prevent any more patients from waking up while under inhaled anesthesia. Anethesia awareness occurs when patients have some degree of consciousness. Michael Avidan of Washington University School of Medicine in St. Louis and colleagues wrote in their report, published in the New England Journal of Medicine:

Our findings do not support routine BIS monitoring as part of standard practice. Reliance on BIS technology may provide patients and health care practitioners with a false sense of security about the reduction in the risk of anesthesia awareness. If BIS monitoring were routinely applied to all patients in the United States receiving general anesthesia, the cost of disposable electrodes alone would exceed $360 million annually.

As many as 40,000 of the 21 million patients undergoing surgery in the United States may experience inadequate anesthesia, leading to anxiety and even post-traumatic stress disorder if the patient regains consciousness, according to the Joint Commission on Accreditation of Healthcare Organizations. Aspect’s Bispectral Index or BIS system assesses brainwaves to help doctors accurately gauge unconsciousness and adjust anesthesia. It is used in about 60% of U.S. operating rooms and is the only system of its kind approved by the U.S. Food and Drug Administration.

Apparently, there has been only a single large randomized study suggesting it worked, and yet it was enjoying widespread adoption throughout operating rooms in the U.S. and throughout the world. The research team looked for evidence of anesthesia awareness in 967 patients monitored by the BIS system and 974 people in a control group that used a long-established monitoring method – standard in new anesthesia machines – that measures the concentration of anesthesia gas exhaled by the patient.

Source: Reuters