Nov. 28, 2007 -- Anesthesiologists today reported that "anesthesia awareness" -- being conscious during surgery -- affects less than 1% of U.S. patients given general anesthesia.
Doctors addressed the topic in a live webcast from New York, spurred by Friday's release of the movie Awake, a fictional thriller based on anesthesia awareness, also called unintended intraoperative awareness.
There have been "a lot of different studies" trying to pinpoint the incidence of anesthesia awareness, Marc Bloom, MD, PhD, of New York University Medical Center, told reporters.
Several studies put the incidence of anesthesia awareness at 0.1% of all general anesthesia patients. That works out to be about 21,000 of the 21 million people in the U.S. who get general anesthesia in a typical year.
But if high-risk patients aren't included, the numbers drop to about one in 40,000 patients, Bloom says.
"But let's get out of this box of how often it occurs. Really, one case is too many," says Orin Guidry, MD, of the Medical University of South Carolina.
"As anesthesiologists, we are not going to stop until we can get that risk down to zero," says Guidry, who is a past president of the American Society of Anesthesiologists (ASA).
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Avoiding Anesthesia Awareness
Anesthesia experts urge patients and doctors to talk about anesthesia before surgery, including a frank discussion about side effects, risks, and past experiences with anesthesia.
Some patients -- including people getting heart surgery, emergency surgery, or C-sections -- may be more likely to experience anesthesia awareness. That's because doctors may need to use a lighter dose of anesthetic to keep the patient (or baby, in the case of C-section) stable.
Patients may remember procedures that involve local anesthesia, but that's not anesthesia awareness, the panelists note.
The use of brain function monitors during surgery can cut the chance of a patient experiencing anesthesia awareness, according to Bloom, Guidry, and colleagues.
But the doctors warn that those devices don't rule out all possibility of anesthesia awareness.
They describe a fine line between too little anesthesia, which may lead to anesthesia awareness, and too much anesthesia, which may cause side effects including nausea and vomiting after surgery.
"We are still in a situation where we have to use all of our senses and all of our knowledge," Bloom says. "At this point, there is no way to flip a switch and let the monitor tell us how much [anesthesia] to give."
The webcast was sponsored by Stryker, which makes a brain function monitor.
Anesthesia Awareness Advocate
All of the doctors who took part in the webcast say they don't know of any of their patients who experienced anesthesia awareness.
But Carol Weihrer, who experienced anesthesia awareness when she was having surgery to remove an eye, says that posttraumatic stress disorder (PTSD) is frequently reported by the thousands of anesthesia awareness patients she's talked to over the years.
Weihrer explains that during her surgery, she got an initial dose of anesthesia but further anesthesia wasn't immediately available because, as she says, "my anesthesiologist hadn't checked his equipment."
"My brain was as alert as it was right now," says Weihrer, calling the experience "very traumatizing." Weihrer is the president and founder of Anesthesia Awareness Campaign Inc.
Guidry, who wasn't involved in that operation, notes that Weihrer's situation may have happened because her anesthesia wore off, not because it didn't work.
Handling Anesthesia Awareness
Tom McKibben, CRNA, past president of the American Association of Nurse Anesthetists, recommends that patients be asked these questions as they recover from procedures involving general anesthesia:
- What is the last thing you remember before surgery?
- What is the first thing you remember after surgery?
- Do you remember anything during the procedure?
- Did you dream during the procedure?
He adds that in the first few weeks after general anesthesia, patients should also be asked what the worst thing was about the operation.
That follow-up may include referrals for counseling to help patients cope with what Weihrer calls the "life-changing experience" of anesthesia awareness.