Asthma Or Something Else - Diagnosing Asthma: Asthma

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Asthma or something else?

Asthma can be hard to diagnose. First of all, it is easy for doctors to overlook asthma in older people, because this disorder is associated more with childhood than adulthood. Sometimes doctors erroneously ascribe breathing difficulties to "getting old" rather than recognizing a medical disorder such as asthma. Second, asthma is sometimes hard to differentiate from other diseases common in older adults that can also cause shortness of breath and sometimes wheezing, like emphysema, chronic bronchitis, or congestive heart failure. To complicate matters further, asthma that has gone undiagnosed or has been poorly treated for years can begin to mimic other chronic respiratory disorders. Even so, the correct diagnosis is usually possible with a thorough medical history, physical examination, and review of medical tests.

COPD

Chronic obstructive pulmonary disease (COPD) is an umbrella term for two conditions that often overlap: chronic bronchitis and emphysema. COPD most often occurs in long-term smokers, although a genetic disease called alpha-1 antitrypsin deficiency can also cause emphysema in people who have not smoked.

Emphysema typically develops in people ages 50 and older. Emphysema does not cause the bronchial tubes to narrow; instead, the disease involves a destructive process that breaks down the elastic substances in the walls of the air sacs. When the lungs lose their elasticity, they are easily expanded (during inhalation) but have difficulty recoiling back to their resting size (during exhalation). Like a rubber band that has lost its stretchiness, the lungs can be pulled open without difficulty but have no spring to push the air back out.

Chronic bronchitis is a persistent and symptomatic inflammation of the bronchial tubes that lasts for years, far longer than acute bronchitis (a chest cold or a deep respiratory tract infection), which normally lasts only for a week or two. Chronic bronchitis, which manifests as daily coughing with white or clear sputum production, is almost always caused by smoking. Years of exposure to tobacco smoke irritate the bronchial tubes and cause them to secrete extra mucus. The "smoker's cough" of longtime smokers is a sign of chronic bronchitis.

Sometimes when people with COPD suffer a respiratory tract infection, they develop more chest congestion and their airways become further narrowed by mucus. When this happens, a wheeze may develop that sounds like the musical wheezing characteristic of asthma. Over time they may have recurrent flare-ups of symptoms, mimicking intermittent asthma attacks. To confuse matters further, bronchial narrowing in people with both COPD and a respiratory tract infection may improve with some of the same medications that are used to treat asthma. For this reason, such people are sometimes said to suffer from "chronic asthmatic bronchitis."

The easiest way to distinguish between asthma and COPD in the elderly is to do a pulmonary function test. Asthma involves reversible airway narrowing, while COPD causes irreversible lung obstruction. That means that people with asthma should have normal or near-normal lung function on their breathing tests when they are well, while people with COPD, even at their best, have permanent lung damage that never goes away.

However, it is sometimes hard to distinguish asthma from COPD even with pulmonary function tests. Someone whose asthma has been undiagnosed or inadequately treated for many years may develop scarring around the bronchial tubes and permanent airway narrowing. It is very difficult to distinguish asthma with permanent airway narrowing from COPD, especially if the person with asthma ever smoked, or if the person with COPD ever had childhood allergies and wheezing before taking up smoking. Sophisticated breathing tests (such as a test of the diffusing capacity for carbon monoxide) and chest CT scanning may be needed to identify the presence of emphysema.

Congestive heart failure

Some people who have had multiple heart attacks or suffered other forms of heart disease develop a condition known as congestive heart failure. In the elderly, this can be hard to distinguish from asthma. Congestive heart failure means the heart loses some of its ability to pump blood. This can lead to fluid accumulation in the lungs and other parts of the body. As fluid collects in the lungs and around the bronchial tubes, it can cause coughing and shortness of breath and sometimes even wheezing. These symptoms can come and go, and they are often worse at night when the person is lying down. It is easy to mistake these symptoms for asthma. One cardiac center reported that as many as 20% of patients with congestive heart failure were originally diagnosed with asthma and were given bronchodilator treatments, sometimes for years, before they were correctly diagnosed with a heart condition.

Other conditions

Chest tumors and blood clots can cause wheezing that is sometimes mistaken for asthma. Elderly people are also more susceptible to swallowing problems than younger people, and thus more likely to inhale food into their bronchial tubes by mistake. This, too, can cause wheezing. Doctors may order x-rays and other chest imaging tests to rule out tumors, blood clots, or aspirated food (see "Laboratory and imaging tests").

Last updated:	September 27, 2007