Help for Hyperventilating

Researchers are developing a new therapy for panic attacks by turning the current treatment for one of the most uncomfortable symptoms—hyperventilation—on its head.

Instead of urging sufferers to take long, deep breaths when they feel they can't breathe, as many were taught for years, researchers from Southern Methodist University say a more effective strategy is to take slower, shallow breaths.

Breathing During a Panic Attack

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In the throes of a panic attack, sufferers experience symptoms like heart racing, profuse sweating and feelings of suffocation. They may think they are having a heart attack or believe they will faint or die. It's unclear if hyperventilation is a cause or a consequence of panic attacks.

Some 10% to 15% of the U.S. population experience occasional panic attacks, usually during a stressful situation, but about 2% develop panic disorder, in which people become so anxious about having attacks that they begin avoiding situations for fear for having one, according to anxiety expert David Barlow, a psychology and psychiatry professor at Boston University.

Only about two-thirds of patients respond to current treatments, says Dr. Barlow. These include medications known as selective serotonin reuptake inhibitors and cognitive-behavioral therapy. The latter teaches sufferers to refrain from thinking catastrophic thoughts when they experience the physiological symptoms and to accustom themselves to the sensations to show that they aren't harmful.

Part of the therapy often involves teaching patients to calm themselves down by taking slow, deep breaths or by breathing into a paper bag.

"It makes perfect sense, the lay suggestion that says take a deep breath," says Alicia Meuret, a professor at SMU in Dallas, who is spearheading efforts to develop the new treatment. And some people do find deep breaths helpful, she says.

But hyperventilation is actually a state of "overbreathing." When people breathe faster or more deeply than normal, they breathe off too much of their carbon dioxide, leading to unpleasant symptoms including anxiety and panic, and at the same time leading the body to restrict the amount of oxygen that gets to the brain.

"They feel like they're suffocating when in fact they feel that way because they have too much air," says Dr. Meuret.

Based on that this understanding of breathing physiology, Dr. Meuret and her colleagues reasoned that breathing less—thus boosting carbon dioxide—should reduce hyperventilation and the anxiety-producing sensations that go along with it.

In the new treatment, called capnometry-assisted respiratory therapy, or CART, people are taught to breathe slower and shallower over four weeks by matching their breathing rate to a series of tones they hear on an audiotape.

Using a capnometer, a machine typically used in hospitals to measure patients' vital signs, patients are taught how to monitor their carbon dioxide and oxygen levels so they can see if they are successfully raising their carbon dioxide levels.

So far, in two small studies of the therapy, Dr. Meuret's group has shown that treatment is effective, at least in the short-term. The first one, published in 2008 in the Journal of Psychiatric Research, involved 37 patients. It showed that participants were able to increase their carbon dioxide levels on a consistent basis and reduce the severity of panic disorder symptoms compared to people who were on a waiting list for treatment. The differences were maintained for up to a year after treatment. A more recent study compared the breathing therapy to another form of commonly used treatment and found that both were effective in reducing panic symptoms. The results were published in September in the Journal of Consulting and Clinical Psychology.

Lisa Nichols, 55, had been seeking help for her panic attacks for about a year when she enrolled in Dr. Meuret's study in 2001. The Millbrae, Calif., consultant had been declining social engagements because she didn't want to leave the house. She tried multiple therapies, including cognitive-behavioral treatment, but none of the treatments decreased the frequency of her panic attacks, which were occurring about once a week.

She found breathing retraining difficult at first. When she began practicing the slower breathing—completing "homework assignments" of 15 minutes twice every day—she felt she wasn't getting enough air, a common experience, says Dr. Meuret. So when she needed to, Ms. Nichols took a deep breath, and moved more gradually toward the target breathing rate.

She has used the breathing techniques since then when she has felt anxious, and has not had a full-blown panic attack in the years since the treatment, she says.

Not everyone is convinced of the effectiveness of the treatment. The concept makes sense, but more research is necessary to show that it works, according to Donald Klein, a psychiatrist and anxiety researcher at Columbia University and New York University who isn't involved in the development of CART.

It's also unclear how easily people can do the breathing retraining on their own without a capnometer, which isn't commercially available. The long-term effects of the treatment remain to be seen.

Write to Shirley S. Wang at shirley.wang@wsj.com