Obesity May Make Anesthesia Riskier

But It's Still Safe for Obese People to Undergo Anesthesia, Study Shows

By Miranda Hitti
WebMD Health News

Reviewed by Louise Chang, MD

Oct. 26, 2005 -- Obesity may raise the risk of complications from anesthesia, a new study shows.

However, obese patients are "very safe" undergoing anesthesia, researcher James Blum, MD, says in a news release.

If that sounds like a contradiction, take a look at Blum's study.

Blum is a resident physician in the University of Michigan's anesthesiology department. He and his colleagues reviewed records of more than 25,000 surgery patients at an unnamed academic medical center.

Most patients -- overweight or not -- had no problem with anesthesia. However, there were 380 reported cases of problems with anesthesia. Obese patients accounted for a significant proportion of those cases.

The findings were presented in Atlanta at the annual meeting of the American Society of Anesthesiologists.

Few Had Problems

All of the participants were adults. Most patients were overweight or obese, based on body mass index (BMI). Only a third of the patients were of normal BMI.

The study doesn't note what type of surgery they had, or any other facts about their health.

The majority had no complications from anesthesia. But the few that did have complications included a sizeable number of obese patients.

Researcher's Comments

"We have found compelling evidence that obese patients are very safe undergoing an anesthetic, but our preliminary data suggest that they are at a greater risk for airway, respiratory, and other complications," says Blum in the news release.

Some of those complications involved problems with placement of breathing tubes. Medical staff may have had trouble inserting breathing tubes in obese patients, or they may have had to reinsert breathing tubes in such patients, the study shows.

There was also an association with dental injuries. Less common problems included strokes, collapsed lung, and cardiac ischemia (cramping of the heart muscle due to a lack of oxygen-rich blood).

Understanding the Risks

Three out of 10 U.S. adults aged 20 and older are obese. That's more than 60 million people, according to CDC data from 1999 to 2002.

Add in people who are overweight but not obese, and the figure soars to 65% of U.S. adults. That means most U.S. adults are overweight or obese.

That's based on BMI. A BMI of 30 or more is obese. A BMI of 25 or more is considered overweight. BMI is calculated based on weight and height.

Obesity has become much more common in recent decades. It's not surprising, then, that Blum's team notes "an increasing number of obese patients presenting for surgery."

Obese patients should be counseled before surgery about their increased risk of complications from anesthesia, write the researchers.

They also call for continued studies to check how obese patients fare with anesthesia.

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