Altered states: How people handle anesthesia is offering clues about consciousness

By David Steinkraus
Journal Times

Wednesday, December 17, 2008 12:32 PM CST

“Ninety-nine,” you say, “ninety-eight, ninety-seven, ninety-six, ninety-five ...” and slowly you slip past that puzzling line which separates consciousness from unconsciousness.

That refrain of counting back from 100 is familiar from the operating room, and it turns out that this common procedure illustrates both the power and the mystery hidden in anesthesia because it is providing many hints about what consciousness is even as it removes the pain and fear which would otherwise accompany surgery.

The question of consciousness is also a very practical one because some people, a very few, don’t stay unconscious. Out of every 1,000 surgeries where general anesthesia is used, one to two people awaken during the surgery and can suffer lasting consequences.

In one sense that’s not many, said Dr. George A. Mashour, director of the Division of Neuroanesthesiology at the University of Michigan Medical School. It means 99.8 to 99.9 percent of surgeries happen without a hitch. But with million of surgeries a year in the United States, it also means a tens of thousands of people are affected, he said.

Then there are the complications, people who can’t have the normal dose of anesthetic for one reason or another. The classic example, Mashour said, is someone with a gunshot wound. The body is already under stress, the circulatory system is already having trouble, and adding anesthetic to that will only repress the body’s functions more, leading to a greater risk of death. Another typical case is a pregnant woman because any drug that goes into her body also affects her child’s.

Awake or asleep?

From a practical standpoint the question of consciousness is decided by a patient’s ability to respond to a doctor’s command, for example to move an arm. That seemingly clear definition has been the standard for more than 150 years of anesthesia use.

“One of the big problems in trying to assess levels of consciousness intraoperatively is that we very routinely administer neuromuscular blockers. So patients are unable to verbally respond. They often have an endotracheal tube in. They can’t follow commands that they’re experiencing pain. They can’t jump off the table,” Mashour said. In experiments doctors have applied tourniquets to prevent muscle-paralyzing drugs from affecting patients’ arms, and have asked patients to respond by moving their hands. “In one study a surprising number o patients were able to give an unequivocal response to a command at some point during their surgery.”

The question remains: Where is that line from knowing what’s happening and not knowing? It’s a profound question, not only for anesthesiologists but for everyone because it’s part of the question of who we are, said Anthony Hudetz of the Medical College of Wisconsin. He holds a doctorate in medical biology, is a professor of anesthesiology, physiology and biophysics, and co-authored a recent paper in Science magazine which discussed what hints about consciousness can be obtained from the study of anesthesia.

It is and isn’t

We can say what consciousness isn’t. It isn’t simple problem solving which is what animals can do. Recent experiments attributed that faculty to a group of crows, all of which figured out that they had to use a short stick to retrieve a long stick which was the only tool that could reach a piece of food.

“So the brain ... 95 percent of what it does happens subconsciously — you know, these well-known examples of driving the car home while thinking about something entirely different, and taking the right exit,” Hudetz said. That’s an example of cognition, processing information, solving problems, but not necessarily being aware of what you’re doing.

What consciousness is, at least at the moment, is self-awareness, knowing that you’re having a subjective experience. It also appears to be a spectrum, appearing and disappearing gradually. Low doses of anesthetics, for example, can cause a state similar to drunkeness.

In the paper which he co-authored, Hudtez and his colleagues suggest that consciousness is the integration of information in the brain. It’s as if the brain was a tiny Internet connecting a bunch of independently functioning computers. When all the computers, all the parts of the brain, are connected and communicating, there’s consciousness; when they’re disconnected, there isn’t.

At the other extreme is a seizure. That, Hudetz said, is a uniform burst of activity across the brain which also removes consciousness because all the circuits are on at once and no part of the brain is communicating with any other.

Forgotten problem

Right now the focus is on explaining consciousness through biology, Mashour said.

“There are still debates about what the right approach is. Some people say it can’t be explained by science. We need to approach this question philosophically … Others say, ‘No actually we need quantum physics.’ ”

Right now, he said, scientists are trying to find out what is happening in the brain when consciousness is present.

For much of the 20th century, he said, no one was paying attention to consciousness at all because the dominant way of thinking about the mind was in terms of behavior. Something happened and there was a certain response. There was another factor, he said, and that was psychoanalysis which emphasized the unconscious workings of the mind; consciousness was considered only the tip of the brain’s activity.

Then, about 20 years ago, prominent scientists began looking at consciousness again through the lens of biology, Mashour said. Yet because so much is still unknown, the field is not totally within the realm of science and strict logical thinking.

“It’s interesting to go to a conference where you have renowned physicists and neuroscientists and also some really fringe, New Age, types who are also participating because right now this subject is broad enough to accommodate all of that,” he said.

Mystery drugs

In their Science paper, Hudtez and his colleagues list the eight common inhaled and intravenous anesthetics and then list the 11 chemical targets of them. Some of the agents suppress some of the targets. Other agents boost the activity of the targets.

“We don’t even know how one anesthetic works, but when you throw three of them on, then it gets more complicated because everything affects everything else,” Hudetz said.

Research has hinted at what regions of the brain may be implicated in consciousness—may be switching points that connect the brain’s various parts — and some companies have developed monitors to check for consciousness, but Hudetz said that without an understanding of how the brain produces consciousness in the first place, it’s hard to design a machine to measure it because the machine can sense only a surrogate.

With better knowledge will also presumably come drugs designed to better target the parts of the brain that produce consciousness. While better than earlier generations of drugs, present anesthetics still affect almost every cell in the body and produce undesirable side effects.

And with better knowledge may come clues to some of the other mysteries of consciousness which have arisen. For example, Mashour said that researchers are now finding that people in vegetative states show a surprising amount of brain activity. A significant proportion of people, 22 percent in one study, report dreaming while under anesthesia, he said.

“Consciousness, in my opinion, is the latest enigma. It’s probably one of the biggest questions for science,” Hudetz said. It used to be taught as only a philosophical problem because it is so very subjective. We really assume that someone else is conscious because they act as we do, he said.

But modern brain science is beginning to chip away at that old barrier, he said, and the implications are vast.

“To what degree am I in charge of my actions?” Hudetz said. “If it’s all hardwired in there — of course affected by learning and prior experience — so what role remains for personal responsibility?”

When anesthesia doesn't work the way it should

About a decade ago, Carol Weihrer had a problem with her cornea, the layer on the front of her eye. She was having severe pain, and it became so bad that her doctors decided to remove the eye.

But the surgery had more lasting effects, and that is why Weihrer formed the Anesthesia Awareness Campaign Inc. (http://www.anesthesiaawareness.com) which she now runs from her home city of Reston, Va.

“Went to sleep, and then I remember hearing disco music, and my doctor was not the type, I would suggest, who listened to disco music … and then I hear him say, ‘Cut deeper. Pull harder.’ … And I started to scream and nothing was coming out of my mouth.”

“I remember hearing other people talking. I felt instruments on my chest. I felt pulling, tremendous pulling on my eye much as if you were having a tooth pulled and you were turning your head the wrong way.”

“I was awake for between 40 minutes and two hours, two and half hours, out of five.”

There was subsequent legal action, she said, and a settlement, but she’s still dealing with the psychological consequences. She said she sleeps in a recliner because she cannot stand the thought of lying flat as in a hospital bed, nor can she tolerate the sound of automatic blood pressure monitors.

She also formed and runs the awareness campaign to help people who have experienced awareness, to change the way anesthesia is practiced, to educate the public, and to encourage the use of brain activity monitoring.

The problem with brain activity monitors is that they don’t necessarily work. A study reported in the spring in the New England Journal of Medicine found that a machine measuring the “bispectral index,” or BIS, was no better than the traditional method of monitoring the concentration of anesthetic gas in a patient’s exhalations.

Anesthesiologists at Froedtert Hospital use monitors but not on every patient, said Dr. Lois Connolly who runs the anesthesia services at the hospital.

Bispectral monitors measure brain waves, and the machine condenses those measurements into a number which the anesthesiologist sees.

“Well you’re hanging your hat on a number,” Connolly said. “And if you can just sit quietly in a chair and meditate, you can lower your BIS value by that alone. You can switch your active beta waves of awake, talking … into more of these alpha waves. It doesn’t mean that you’re unconscious or unresponsive.”

Then there are the complications introduced by each individual patient, Connolly said. Drug addicts, or just longtime users of some drugs, will be more resistant to those used in some phases of anesthesia. The sicker people are, the more likely they are to be aware during anesthesia.

The age of a person determines how they respond to anesthesia, but a person’s biological age does not necessarily equal the years on a calendar. And it’s extremely difficult to determine a person’s biological age.

Froedtert has added a notice about the possibility of awareness to its consent form, Connolly said. And patients need to realize that some memory of surgery is acceptable, such as memories of being wheeled into an operating room or waking up as one is being taken out.

Because of all the uncertainties in and problems with monitoring consciousness, she said, we’re left with education — of the people caring for patients and of the general public, but education without causing alarm. “Because it’s not meant to be alarming. It’s meant to be open. Let’s have an open discussion about this, and if a patient comes in with a concern about this let’s talk about it and tell people how we approach it to try to decrease that incident from happening.”

“We don’t what to scare people out of having surgery,” Weihrer said. “We want to spare them having awareness.”

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