Asthma Healing

It's a deadly lack of sensitivity. One in four asthma sufferers can't tell when they're about to have an attack. They don't know they have this problem. They don't get help in time. They're much more likely to die.

But there is good news. Tests -- which must be done by a lung specialist -- can show how well a person with asthma can predict an attack. It's knowledge that can save your life or the life of a loved one.

Doctors call it "perception of dyspnea" or POD. POD is the ability to know when you're starting to get short of breath. For a person with asthma, this is especially important. Asthma drugs can prevent a serious attack, but only if they're taken in time.

"The problem with patients having low POD is that they are not aware when an attack ... occurs," study leader Paltiel Weiner, MD, tells WebMD. The study is published in the February issue of Chest.

Weiner says that people who can't tell when an asthma attack is on the way don't take their asthma medicine on time. They are less likely to recognize a life-or-death situation and don't call the doctor soon enough.

It's a common but little-known problem, says Susan K. Pingleton, MD, director of pulmonary and critical care medicine at the University of Kansas Medical Center.

"We had a patient with such bad asthma that she called us on the telephone," Pingleton recalls. "Before the paramedics could come, she collapsed. That patient probably has this problem. When it gets bad enough for these patients to know it, it can be too late."

Weiner's team studied 113 patients attending an outpatient asthma clinic in Israel. They tested the patients' POD. More than one in four of these "stable" asthma patients had low POD -- that is, they didn't know when they were short of breath. Over the next two years, these patients were more likely than other patients to have a fatal or near-fatal asthma attack. They also were more likely to end up in the hospital after an attack.

"All patients with asthma should -- at least once -- be evaluated for POD," says Weiner, head of the department of medicine at Hillel Yaffe Medical Center, Hadera, Israel.

There are two POD tests. One is a device that makes a patient breathe through a chamber with a plunger attached to weights. As the weight is increased, it gets harder and harder to draw a breath. The other test is to have the patient inhale progressively larger doses of a drug that makes a person short of breath. Most doctors prefer the first technique, Pingleton says.

Why get tested? Pingleton says people with low POD should be aware of their condition and act accordingly. They should get help at the earliest sign of trouble.

"One of the most important things is to tell patients that what they have is like a high pain threshold," she says. "I say, 'For you, it takes a whole lot less shortness of breath before you are in trouble. The first time you feel short of breath, let me know.' The patients need to know that their symptoms are blunted and they should react a different way from how we usually tell patients to react."

Nobody knows why some patients have low POD and others don't. Because perception happens in the brain, Pingleton says, it's most likely a combination of physical and psychological factors.

Weiner notes that low POD is most common among older asthma patients and those who have had asthma the longest. He suggests that chronic asthma inflames the lungs and that this inflammation makes it harder to sense shortness of breath. For such patients, he recommends inhaled steroidal drugs, such as Azmacort or Pulmicort.