by Bahar Gholipour
September 19, 2013
With anesthetics properly given, very few patients wake up during
However, new findings point to the
possibility of a state of mind in which a patient is neither
fully conscious nor unconscious, experts say.
This possible third state of consciousness, may be a state in
which patients can respond to a command, but are not disturbed by
pain or the surgery, according to Dr. Jaideep Pandit,
anesthetist at St John's College in England, who discussed the idea
today (Sept. 19) at The Annual Congress of the Association of
Anaesthetists of Great Britain and Ireland.
Pandit dubbed this state dysanaesthesia, and said the
evidence that it exists comes partly from a recent study, in which
34 surgical patients were anesthetized, and had their whole body
paralyzed except for their forearm, allowing them to move their
fingers in response to commands or to signify if they are awake or
in pain during surgery.
One-third of patients in the study moved their finger if they were
asked to, even though they were under what seemed to be adequate
anesthesia, according to the study
led by Dr. Ian F. Russell, of Hull Royal Infirmary in
England, and published Sept. 12 in the journal Anaesthesia.
"What's more remarkable is that they
only move their fingers if they are asked. None of the patients
spontaneously responded to the surgery. They are presumably not
in pain," said Pandit, who wrote an editorial about the study.
Normally, while patients are under
anesthesia, doctors continuously monitor them, and administer
anesthetic drugs as needed. The goal is to ensure the patient has
received adequate medication to remain
deeply unconscious during surgery.
However, it is debated how reliable the
technologies used during surgery to "measure" unconsciousness are.
"We don't have a model for
consciousness," Pandit said. "It is very difficult to design a
monitor, to monitor something you don't have a model for."
Things You Didn't Know About the Brain]
The study of 34 patients was aimed at
investigating whether patients are fully unconscious when the
monitoring technology commonly used in the operating rooms indicates
The researchers kept patients' arms
separated from rest of the body, which was receiving routine
paralyzing drugs, by blocking the blood supply. Patients were able
to move their arm if they were still conscious.
In the patients who responded to the doctor's command by moving
their hand, the doctors took it as a sign of consciousness, and
increased the anesthetic dose.
However, Pandit argues these patients were not "conscious." The fact
that patients only responded to command, and didn't move
spontaneously shows their state of mind is different from normal
consciousness, he said.
The idea of a third state of consciousness may explain the
discrepancies in the reported prevalence of awareness during
surgery, Pandit said. Previous surveys have shown that when patients
are asked if they recalled being aware during surgery, about 1 in
500 will say they did.
In contrast, a recent national survey in
the United Kingdom, in which patients were not directly asked about
awareness during surgery, 1 in 15,000 patients spontaneously
reported they were aware during their surgery. Only 1 in 45,000
reported pain or distress during their surgery.
Together, these statistics suggest there's a state in which patients
are aware but not reporting it, perhaps because it is an acceptable
and neutral experience for them, Pandit said. They may be aware of
their surroundings to some extent, but not concerned by this
knowledge, especially because they are not in pain.
Pandit's hypothesis may serve as basis for developing anesthesia
monitors in the future, he said.
Although the state of dysanaesthesia
seems harmless, it could be a precursor to unpleasant awareness
during surgery that doctors, and patients, wish to avoid.
"It's a hypothesis for future
research, it's something that we can explore further and design
experiment to see if it really exist," he said.