When asthma strikes, it is usually due to a constriction in the air passageways, which disallows a person to breathe normally and even produce a wheezing sound in severe cases. The main factors that cause the airways to become narrowed and blocked during an asthma attack include a constriction of the muscles surrounding the air tubes, an inflammation and swelling of the lining of the air tubes, and an increase in mucus production, which clogs the air tubes.



Twitchy Airways

The air tube is made up of several layers. On the outside of the air tube there is muscle which, by tightening and relaxing, controls the size of the opening of the air tube (the space through which air must pass). The muscle works by reflex, and is guided by the same portions of the nervous system that control reflexes, like involuntary blinking.

We have little conscious control over the tightening and relaxing of these muscles. Everyone's airways have the potential for constricting in response to irritant, such as cigarette smoke, perfume, or newsprint. In the asthma patient the airways are overreactive and have been described as 'twitchy'.

The overreactive asthma airway responds not just to allergens (like cat dander and ragweed) but also to other factors, like viral infections, barometric pressure changes, exercise, and cold air. During an asthma attack, the muscles surrounding the airways tighten, causing airway narrowing.

Asthma is not a problem limited to muscular constriction of the airways. An equally important problem is the inflammation of the lining of the airways. Inflammation can be understood by describing what happens when you scrape your knee. The scraped area becomes swollen and oozes with a fluid that contains many kinds of cells, some of which help to fight infection.

However, this fluid also contributes to the swelling. In asthma, the innermost lining of the airways is filled with cells and fluid that, as with the scraped knee, are a product of the inflammatory response. These cells and the associated swelling contribute to the obstruction of the airways in asthma attacks. Steroids, the medication most often utilized for difficult to manage flares of asthma, help to reduce inflammation in the airways.

Mucus Plugs

Mucus, which normally lubricates the airways to allow air to flow smoothly, increases in amount during asthma attacks and serves as a sticky plug to clog the airways, especially the smaller ones. All asthma patients are aware of the sensation of trying to cough up mucus. Often, they feel that if they could clear their airways by coughing up a sufficient amount of mucus, their asthma symptoms would subside.

But frequently there is so much mucus that even if one mucus plug is brought up, the same sensation and symptoms persists. It is important to seek your doctor's advice early on if you are unable to clear mucus plugging your airways, since neglected mucus plugging often prolongs asthma attacks.

In addition, when the plugs are allowed to linger they can become a source of infection. For this reason, an antibiotic is often prescribed for patients who are slow to respond to treatment during an asthma attack.

Asthma attacks at varying time intervals. The attacks can be as brief as several minutes or as lengthy as hours or days. Between attacks, there may be symptom-free intervals when it is impossible to tell an asthma patient from someone who does not have it.

A breathing test called spitometry, which is used to determine whether a person has asthma, may be normal in an asthma patient during an asthma-free attack. Nevertheless, spirometry is an important clue for determining whether a patient has asthma and should be part of the doctor's evaluation.