BODY WATCH : Rude Awakening : Imagine the horror of waking up during surgery and feeling every move. It happens.
As Patricia Lodge was being anesthetized, she thought her next waking moment would be in her hospital room. Instead, she emerged out of unconsciousness into a living nightmare.
She woke up in the middle of her own operation.
She couldn’t open her eyes, but she could hear everything. Panic filled the operating theater. Lodge was hemorrhaging. Her surgeon, unable to stop the bleeding, was cursing furiously. A nurse slipped and fell in Lodge’s blood.
Lodge was terrified. “I wanted to yell, ‘Stop! Stop! I’m here!’ ” But she couldn’t move or utter a sound. She was still under the effect of a paralyzing drug.
“I managed to lift my right index finger just a little,” she recalled. “I heard somebody yell, ‘Oh, God! She’s coming around! Get her out! Get her out!’ ”
Of the 20 to 25 million people who undergo surgery every year, researchers estimate 0.2% to 1%--40,000 to 250,000--remember waking up during general anesthesia. Unable to move, they look as if they are unconscious, but they are not.
Most who wake up feel no pain or fear. They drift peacefully back into unconsciousness. After surgery, they either don’t remember or don’t care about the incident. Some, though, have horrific experiences, as Lodge did, and suffer post-traumatic stress disorder. They can’t sleep, they have nightmares, they withdraw from society, their emotions are blunted.
An even smaller percentage--no one really knows how many--feel pain. Recalled one patient: “I remember them splitting my ribs open. The stab was bad, but the surgery was a lot worse.”
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At the base of the terror experienced by some of the people who become aware during surgery is a little known fact: anesthesiologists don’t have a machine that monitors patient unconsciousness.
It’s not simply a matter of checking to see if the patient is sleeping, notes Henry Bennett, an experimental psychologist and associate professor of clinical anesthesiology at UC-Davis, Medical School. Bennett has studied 60 people suffering from post-traumatic stress disorder after awakening during surgery.
“Anesthesiologists say that people go to sleep during surgery. But that’s an obfuscation. There is no relationship between sleep and anesthesia,” he said.
“Sleep is a physiological state,” said Dr. Peter Sebel, professor of anesthesiology at the Emory University School of Medicine. “If someone sticks a knife in you when you’re sleeping, you wake up. If you are under anesthesia, you are in a non-physiological state, a reversible state of unconsciousness, drugged to the point of reflex suppression.”
What is not generally understood is that people who undergo general anesthesia usually receive four different types of medications: a mild tranquilizer to make them forget events; narcotics to block pain; an anesthetic, such as sodium Pentothal or propofol, to make them lose consciousness; and an agent that paralyzes patients so that they won’t move when surgeons or anesthesiologists severely stimulate nerves, such as cutting open their rib cages or shoving a breathing tube down their throats.
These drugs were developed to control the five components of general anesthesia during surgery: unconsciousness, analgesia or lack of pain, amnesia or forgetting events, lack of responsiveness or movement and muscle relaxation.
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People wake up during operations for three reasons. They may be unexpectedly tolerant to the drug that induces unconsciousness--individual tolerance to a drug may vary tenfold. Physicians may err in administering an anesthetic. Emergencies during surgery, such as when Lodge hemorrhaged and her blood pressure dropped, require physicians to decrease anesthetic to maintain blood pressure so as not to injure the brain, heart, kidneys or, during Cesarean sections, the fetus.
In fact, some people who are severely injured and undergo emergency surgery are too close to dying to be given an anesthetic--the drug would finish them off.
“People have tried to develop depth-of-anesthesia monitors for 50 years,” said Dr. Ira Rampil, assistant professor of anesthesiology at the University of California San Francisco Medical School, where he is also medical director of the neurophysiological monitoring service.
But only recently has the work begun to demonstrate any encouraging results. Four devices are being tested to detect unconsciousness during surgery, as well as to detect pain in people, such as patients in intensive care units and children, who are unable to tell medical practitioners.
One promising new technology, called 40-hertz auditory steady state response is similar to an electroencephalogram (EEG) in that it detects brain waves--electrical signals that pass from the cerebral cortex through the skull. This machine, however, screens out all of the signals except those that the brain makes in response to a 40-hertz sound signal.
Anesthesiologist Gilles Plourde is testing the device at Royal Victoria Hospital in Montreal. Plourde, also an assistant professor at McGill University, says that anesthetic drugs seem to interfere with a part of the brain that relies on 40-hertz signals to communicate between the cortex and the thalamus.
“Anesthetic agents make the cells unable to generate a fast and oscillating signal. If the cells lose the ability to generate the signal, you probably lose consciousness,” Plourde said.
So far, the technique detects the disappearance of the brain’s response when tested with more than 100 anesthetic agents, and has not worked with only one--Ketamine. In testing with humans, Plourde has found an “excellent correlation” between disappearance of the 40-hertz signal and lack of responsiveness when he asks them to open their eyes or squeeze his hand.
But the testing has been done during general anesthesia when patients receive a drug called Sufentanil, which commonly causes involuntary movements. Because he doesn’t really know if patients are conscious when their brains are giving off a signal, he will do more definitive testing this year.
Another device, dubbed the Face machine, detects the rate of contraction of four muscles in the face: frontalis, corrugator, zygomatic, and masseter. The frontalis expresses surprise, the corrugator makes a frown, the masseter clenches the jaw, and the zygomatic forms a smile.
During surgery, if there is more frowning and grimacing going on than surprise or smiling, a person is experiencing the stress of awareness or pain. As the rate of contraction increases, a patient may be close to waking.
The rates of contraction of these muscles are so low that they cannot be detected by the human eye. The unique type of contraction of these muscles, however, is what enables a device to detect their movement.
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Preliminary testing earlier this year indicated that as long as levels of a paralyzing drug do not indicate more than 90% muscle paralysis--which is enough for surgery, said Bennett--the device can measure the facial muscles’ response to awareness and pain.
The device was tested on patients undergoing surgery by isolating one of their arms from the paralyzing drug by means of a tourniquet and by asking the patients to squeeze the hand of the researcher once at his request, and twice at his request. Bennett assumed loss of consciousness at the point that patients no longer responded to his requests.
The Face machine is undergoing testing at the University of California, San Francisco, Medical School to assess acute pain of people in intensive care units who are kept sedated and immobile while they are on ventilators.
Two other techniques, originally developed to predict a patient’s likelihood of moving while under anesthesia, may also hold promise for monitoring awareness. The first, called a bispectral EEG is being tested by Sebel at Emory University, and hospitals in Massachusetts, San Francisco, San Diego and Stanford.
Developed by Aspect Medical, a company in Framingham, Mass., the device uses declassified naval sonar technology to detect a physiological response that can predict whether a patient under anesthesia will move as a response to a skin incision.
The other approach, called mid-latency auditory evoked potential (MLAEP) measures a brain signal that responds to sound. Being tested in Great Britain and Germany, anesthesiologists have used the presence of a MLAEP signal to stimulate the delivery of an anesthetic during surgery, on the theory that patients who have a MLAEP response are not unconscious enough.
These devices should be fully tested and ready for the market in no sooner than two years. They’re likely to find some buyers, said Sebel, because, “3% of the suits against anesthesiologists relate to patient awareness.”
Economics isn’t the only reason anesthesiologists are concerned, he emphasized: “From a humanitarian point of view, people need to be unaware during surgery.” Indeed, one survey by anesthesiologists showed that 50% of patients interviewed before surgery say their main fear was waking up during the operation.
