In early August, U.S. News explored the unsettling phenomenon known as anesthesia awareness. It's just what it sounds like—finding yourself conscious while you're having surgery. The story looked into a brain-monitoring technology designed to prevent that from happening and whether the American Society of Anesthesiologists would put its collective muscle behind the technology at the group's annual meeting in October.

This Tuesday, at the now concluded meeting in Atlanta, the ASA issued its answer, and it was neither a wholehearted "Yes" nor an emphatic "No." Coming down squarely in the middle, the society's house of delegates approved a "practice advisory" that leaves it to individual practitioners to decide whether to use the technology.

How often a patient awakens or never loses consciousness during an operation can't be known. The ASA cites studies concluding that the rate is about 1 to 2 for every 1,000 patients. But patients undergoing surgery generally receive paralytic drugs to keep them motionless while delicate work is going on. If someone whose body is paralyzed gains consciousness, there's no way to signal doctors or nurses, even by blinking rapidly or waving a finger. Anesthesiologists have numerous monitoring devices at their disposal, but none directly assess consciousness.

None, that is, except devices that evaluate brain waves, which are only gradually finding their way into operating rooms. By far the biggest player is Aspect Medical Systems, a Newton, Mass., manufacturer of bispectral index, or BIS, monitors. A plastic sensor on the patient's forehead sends brain waves to a computerized unit that combines them and converts them to a number from zero to 100, with 100 representing full consciousness. The company recommends keeping patients in a range of 40 to 60.

Many anesthesiologists consider BIS monitors unproven. Still, Aspect Medical CEO Nassib Chamoun says he was pleased by the ASA's action in Atlanta. It was a tepid endorsement of brain monitors, but, he says, the delegates could have voted down the advisory altogether: "To be recognized in a practice advisory is a great step forward, and as much as can be expected at this point." And as the delegates who voted represent practicing anesthesiologists, their action "reflects the views of the members."

That's because for better and for worse, organized medicine can be slow to adopt innovation. Take pulse oximetry, which uses a probe slipped over a finger or earlobe to monitor the blood's oxygen level during surgery. No anesthesiologist would be without the device. But it took the ASA until 1987 to begin evaluating pulse oximetry, when it already was employed in 80 percent of operating rooms. By 1992, when the ASA officially approved the technology, hardly an OR or intensive-care unit was without it.

Chamoun sees a parallel with BIS monitors, which he says are present in about 40 percent of hospital ORs and are used on about 12 percent of all patients who receive a general anesthetic. That amounts to about 2.4 million patients a year out of 20 million who undergo surgery with a general.

New ASA President Orin Guidry, an anesthesiologist at Ochsner Clinic in New Orleans, personally believes that certain patients should be monitored. Among them: cardiac patients under light anesthesia to keep the heart from being stressed; trauma patients for the same reason; emergency cesarean patients whose anesthesia has to be minimized to protect the baby—and patients who express concern about awareness. "They are reassured when we tell them we will use a monitor," says Guidry.

The ASA delegates also recommended this week that the group look into the feasibility of a clinical trial, or trials, large enough to put BIS monitors to the test. But because the probability of awareness is deemed so low, a huge number of patients would have to be enrolled—"some 750,000," says Guidry. "Can this question be answered in a way society can afford?"

To patients who have experienced one of these events, the point is moot—those who know about BIS monitors don't understand why they aren't omnipresent. Carol Weihrer, who was completely conscious most of the time her diseased eye was being removed, has been a constant critic of the profession, which she believes has acknowledged neither the problem nor the remedy.

Weihrer agrees, however, that adopting the advisory "was a big pill for ASA to swallow—to admit that there is a problem. But it's just a baby step." Weihrer, who after her experience created a Web-based effort called Anesthesia Awareness Campaign, wants to see ASA emphasize to its members the need to ask all anesthesia patients whether they awakened during surgery, to investigate all such reports, and to provide psychological counseling when necessary. Those actions were mentioned in the report adopted by ASA this week, but not as mandates.

Meanwhile, says Weihrer, "until BIS monitors are in every OR, my work will not be done."