Researchers at Washington University School of Medicine in St.
Louis compared two groups of about 1,000 patients each, all deemed at high risk of waking up during surgery because of health conditions, medication or other factors.
One group used the leading brain-monitoring system, which uses electrodes on the forehead to measure brain waves and software to calculate likelihood of consciousness. The other used an older device that analyzes exhaled anesthetic gas.
Anesthesiologists watched for movement and changes in vital signs and followed protocols to maintain patients' depth of sleep, adjusting anesthesia levels as needed. Patients were interviewed after their surgeries about what they remembered.
Two people in each group had experienced awareness - and the two monitored with the newer system reported having felt pain as well.
Lead researcher Dr. Michael Avidan said that in two of those cases - one with each system - the monitors indicated no problems with the anesthesia. In the other two cases, the monitors signaled problems.
The study analyzed groups of people who had surgery at the university's partner hospital, Barnes-Jewish in St. Louis, in 2005 and 2006. It was published in Thursday's issue of the New England Journal of Medicine.
Anesthesia awareness occurs in 1 or 2 of every 1,000 surgical patients - possibly more often in children - and is thought to happen to roughly 30,000 Americans each year.
Some just have fleeting memories of things they heard, but others describe "white-hot pain" and terror, triggering long-term emotional problems.
Carol Weihrer of Reston, Va., said that 11 years after awakening during surgery to remove a diseased eye that caused severe pain, she still has post-traumatic stress disorder, can sleep for just short periods and suffers mood swings and panic attacks.
Weihrer, who founded the group Anesthesia Awareness Campaign Inc., said she heard the doctor give instructions: "Cut deeper, pull harder." "I actually saw them cut the optic nerve when everything went black," she said.
"While you're laying there on the table," she recalled, "you are thinking, praying, cursing, plotting, pleading, trying to crawl off the gurney, trying to kick, scream, move any part of your body to let them know you're awake. In effect, you are entombed in a corpse."
Kathy LaBrie of Nashua, N.H., also suffered awareness during surgery for a deviated septum. She said she heard "the sound of pushing and grinding and the surgeon talking to the nurses about the kind of car he had. ... I tried moving my arms and legs - I couldn't do anything. I thought I was dying."
Dr. Jeffrey Apfelbaum, president of the American Society of Anesthesiologists, who was not involved in the study, said there is "tremendous pressure" from industry and patient advocates to use the brain-wave technology, despite the lack of solid evidence that it works better.
The position of the anesthesiologists group has been that brain-wave monitoring should not be done routinely, but may be helpful for certain patients at high risk of awareness. But widespread use would be very costly.
The dominant maker of brain-wave systems, Aspect Medical Systems, says its monitor, called a bispectral index or BIS, is used in about 17 percent of the roughly 20 million U.S. surgeries each year in which anesthesia gas is used.
The device can cost as little as $5,000. But the researchers estimated that if it were used on all U.S. patients getting general anesthesia, the disposable electrodes alone would cost more than $360 million a year.
The device, on sale since 1998, "can prevent both too little anesthesia, which could cause awareness, and too much anesthesia, which could cause prolonged recovery and anesthetic side effects" such as grogginess and nausea, said Aspect's medical director, Boston anesthesiologist Dr. Scott Kelley.
He said the new results show the system can help anesthesiologists "achieve a very low incidence of awareness in high-risk patients."
But Avidan's fellow researcher, anesthesiology professor Dr.
Alex Evers, said he thinks having doctors closely follow a protocol to maintain the patients' depth of sleep was the key to reducing anesthesia awareness in both groups.
The Food and Drug Administration has stated only that the BIS device "may be associated" with reducing awareness during surgery.
About 10 percent of U.S. surgical patients receive intravenous anesthesia, without any gas. The study findings do not apply to them.
Dr. Douglas Jackson, assistant anesthesiology professor at University of Medicine and Dentistry of New Jersey in Newark, said the study shows the BIS system "is not a magic bullet."
"We still don't have a monitor that can tell us about depth of anesthesia (and) awareness," he said, adding that controlling that is still an art.
---
On the Net: http://www.nejm.org
Anesthesia Awareness Campaign Inc.: www.anesthesiaawareness.com
