Chicago: Instead of a deep sleep, general anaesthesia is more like a
reversible drug induced coma, US researchers said on Wednesday, in
findings that could lead to better treatments for coma and better
“General anaesthesia is pharmacological coma, not sleep,” said Dr
Nicholas Schiff of Weill Cornell Medical College in New York, who worked
on the study with Dr Emery Brown of Massachusetts General Hospital and
Dr Ralph Lydic of the University of Michigan.
Their findings, published in the New England Journal of Medicine,
represent a three-year exploration of the similarities and differences
of sleep, anaesthesia and coma.
They said while doctors and patients commonly describe general
anaesthesia as going to sleep, there are significant differences between
the states, with only a bit of overlap between the deepest states of
sleep and the very lightest phases of anaesthesia. While sleeping
usually involves moving through a series of phases, in general
anaesthesia, patients are typically taken to a specific phase or state
and kept there during the surgery. This phase most closely resembles a
“The brain is becoming very, very quiet. The activity of the neurons
is being dampened dramatically,” Schiff said in a telephone interview.
“That is also true in coma.”
Schiff, an expert in coma recovery, said while no two brain injuries
are alike, studying the way people come out of anaesthesia could be used
as a model for predicting the stages of emerging from a coma.
“Although recovery from anaesthesia is much faster, there are hints
that some of the circuit mechanisms have some overlap,” he said.
That could lead to monitoring tools and diagnostics to assess what
stage of recovery a person with a coma is in, and it could be used to
develop new strategies to help doctors bring patients back to
Knowing more about the brain circuit mechanisms may also help
researchers develop drugs to tweak specific brain circuits, Schiff said.
And the study should lend new insight into understanding general
anaesthesia, Brown, an expert in general anaesthesia, said.