Anesthesia News update

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June 27, 2005 Los Angeles Times

Even when surgery is over, sedation's risks could linger

Death rates are higher for months afterward, studies find. Doctors

search for a reason.

By Shari Roan, Times Staff Writer

Anesthesia is not an area of medicine most folks profess to

understand. As one anesthesiologist put it: " The lay public has the

notion that we knock people on the head and they go to sleep, and

then we knock them on the head again and they wake up. "

But today, even doctors are realizing how little they know about the

effects of heavy sedation.

Since the beginning of modern medicine, doctors who administer

anesthesia have largely confined their worries to the period

beginning when patients are sedated and ending when they're fully

awakened. Now, two startling studies suggest that the effects of

anesthesia linger for a year or longer, increasing the risk of death

long after the surgery is over and the obvious wounds have healed.

" We don't know whether the things we do really have an effect that

lasts out to a very long period of time, but there is enough evidence

to suggest it might, " says Dr. Gaba, a professor of

anesthesiology at Stanford University School of Medicine. " Even if

it's a subtle and fairly uncommon phenomenon, it could affect an

awful lot of people. "

About 20 million Americans undergo surgery with general anesthesia

each year.

Worries about the long-term effect of anesthesia — and the demands

for additional studies — began to emerge recently when two research

groups published papers linking deep sedation and an increased risk

of death in the year or two after surgery.

One study, presented last fall at the American Society of

Anesthesiologists annual meeting by Swedish researchers, showed that

the duration spent under deep anesthesia is a significant risk factor

for predicting death up to two years after surgery. Although the

patients in the study were undergoing non-cardiac surgery, most

deaths resulted from heart attacks or cancer.

The other study, published in the journal Anesthesia & Analgesia in

January by Duke University researchers, found that longer amounts of

time spent under deep sedation increased the risk of death in the

year following surgery. The patients in the Duke study underwent

major, non-cardiac surgery with general anesthesia, and again, deaths

in the first year after surgery were primarily from heart attacks or

cancer.

" The idea that what we do in the operating room may impact outcomes

in our patients weeks, months or years down the road is exciting, "

says Dr. Steffen E. Meiler, vice chairman for research in the

department of anesthesiology and perioperative medicine at the

Medical College of Georgia.

Surgery experts and anesthesiologists met in Washington, D.C., last

fall and at smaller regional meetings since then to discuss the

findings and plan research that could answer their questions. So far,

doctors seem to agree that the long-term effects of surgery and

anesthesia can lead to deaths. But they don't agree on the precise

cause.

Some experts suggest that anesthesia and surgery may ignite a cascade

of inflammation in the body that can aggravate heart, respiratory,

cancer conditions or dementia.

According to the leading theory — just a hypothesis for now — surgery

and anesthesia trigger the release of stress hormones, such as

norepinephrine, that in turn activate inflammatory responses in the

body and undermine the workings of the immune system. Inflammation is

known to worsen many diseases, including heart disease, cancer, even

dementia.

Since the first studies were published, newer research has suggested

that non-cardiac surgery with anesthesia also can cause a cognitive

decline in some elderly people up to two years after the surgery,

says Dr. Terri G. Monk, a professor of anesthesiology at Duke who led

the study. That data was presented last fall at the American Society

of Anesthesiologists annual meeting.

" Neither surgery nor anesthesia is a natural thing, " Gaba says. " What

some people suspect — but there is still not much evidence for — is

there could be people whose inflammation processes don't come back to

normal after surgery but stay revved up for a very long time. "

Surgery itself causes pain, stress and anxiety, Meiler notes. Then

there's the anesthesia, perhaps blood transfusions, and usually

hypothermia (low body temperature) during surgery — all of which can

rattle the immune system in a profound way.

Sicker, older and obese people may be at more risk for death longer

after surgery.

" What we're now starting to learn is maybe there is a zone that we've

always accepted as fine before that may have some subtle effects that

we didn't know about before, " Gaba says.

Although doctors must be able to blunt pain, keep a patient from

moving and block awareness and memory during surgery, they also must

be able to awaken the patient soon after the surgery. If the new

findings hold up, they'll have even more reasons to give patients as

little anesthesia as necessary — and to take additional measures to

protect patients.

Newer monitors that precisely gauge a patient's sedation level could

help improve safety, says Dr. Lew, chairman of anesthesiology

at City of Hope National Medical Center in Duarte. Accounts of

patients waking up during surgery had spurred the development of the

sophisticated monitors, but even with the monitors, doctors face a

balancing act.

" What has evolved is a feeling that maybe, at times, anesthesia is

not deep enough and that we need better monitors to look at the depth

of anesthesia, " Lew says. " On the other hand, Monk's study is saying

if you run them too deep, you increase mortality. "

Doctors also say that giving patients certain drugs before surgery

can offset the risks of death later. For example, beta-blockers,

drugs that control hypertension, are recommended for many patients

before non-cardiac surgery to reduce the risk of postoperative death.

Beta blockers can relieve stress on the heart during surgery. A 2004

study, however, showed that only about 40% of the suitable candidates

for the prevention measure received it.

Two recent studies, Meiler says, show that statins given to patients

undergoing major vascular surgery could protect against death after

surgery by improving the patient's cholesterol levels and stabilizing

plaque in the arteries' walls to avoid rupture.

Preoperative visits between the patient and anesthesiologist

increasingly may include discussions about minimizing the long-term

risks of surgery. Certain patients may be safer with a particular

type of anesthesia, for example.

With continuing research, Meiler says, " The preoperative visit is

going to reach a new level of sophistication. "