Doses are calculated based on a variety of factors, among them body weight, body fat and medical history. Alcohol, obesity and certain drugs can affect how much anesthesia is necessary. As with all medications, people metabolize anesthesia at different rates, said Emory's Sebel.
It is the job of the anesthesiologist or nurse anesthetist to continuously monitor the patient's condition through vital signs including blood pressure, respiration and heart rate to ensure the patient is unconscious, stable and pain-free.
Jodie Stanley awoke from anesthesia during an operation on her right hand.
(Steve Gates - For The Washington Post)
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It Knows When You're Awake (The Washington Post, Nov 23, 2004)
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Robert Wise, M.D., vice president at the Joint Commission on Accreditation of Healthcare Organizations, was online to discuss patients who wake up during surgery.
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But these signs can be imperfect markers, doctors say, because beta blockers, along with other drugs, can depress blood pressure or affect heart rate. A patient who wakes up during surgery might not show a jump in either sign, anesthesiologists say.
Some doctors compare the situation to flying through fog: A pilot relies on instruments and expertise, but can't see clearly.
"Anesthesiologists think they can measure the depth of anesthesia, but there are times when this is not true," said Mohamed M. Ghoneim, a professor of anesthesiology at the University of Iowa. "It's really difficult to measure, especially in light anesthesia such as cardiac cases or trauma with lots of blood loss."
Measured Response
The best way to detect whether a patient is sufficiently anesthetized is by using a specialized EEG machine that monitors brain waves, said Ghoneim. He predicts such monitoring will become the standard of care in a few years.
Ghoneim said he routinely uses a bispectral index (BIS) monitor, a device JCAHO officials say they consider promising. The Food and Drug Administration, which first approved the device in 1996, last year authorized manufacturer Aspect Medical Systems to market it for awareness reduction. Earlier this year two prospective studies involving more than 7,000 patients found that the monitor, the leading brain wave device on the market, reduced the risk of anesthesia awareness by about 80 percent.
Many anesthesiologists and nurse anesthetists have resisted using the BIS and similar monitors because the devices have not been "peer-vetted" by their professional societies. Many say they consider the clinical judgment they exercise monitoring vital signs to be a better way of gauging whether a patient is awake than using a brain wave monitor.
Among them is Litwiller, who said a task force composed of ASA and AANA members is studying the issue and may make recommendations late next year.
"This problem should be solved by good science, not emotion," he said. "Good science takes time." Awareness is a problem that "has been around -- it didn't just pop up yesterday."
Denial of Awareness
Psychiatrists say that when doctors minimize or deny intraoperative awareness, patients tend to suffer more severe psychological problems. Numerous studies of malpractice have found that doctors who stonewall patients after a serious injury are more likely to be sued than those who are forthcoming.
