asthma
Meaning of asthma: Two problems run together here: inflammation that smolders between attacks and muscle spasm that closes the airway during one.
Definition of asthma
Asthma is a long-term condition in which the airways are inflamed and overreactive, narrowing in response to triggers that leave other people unaffected. The muscle wrapped around the airway tightens, the lining swells and mucus builds up, so air moves out with difficulty. Wheezing, coughing, chest tightness and breathlessness come in episodes, and the narrowing is largely reversible.
What happens during an attack?
Three changes narrow the airway at the same time. A band of smooth muscle wrapped around it contracts, the lining underneath swells with inflammation, and glands in the wall pour out thick mucus. Air can still be drawn in, because breathing in widens the chest and pulls the airways open, but pushing air out squeezes them further and traps it behind the narrowing. That is why breathing out is the harder half, why the chest feels tight and overfilled, and why the whistling sound is loudest on the way out. Between episodes the airways may work almost normally while the inflammation quietly continues.
What sets it off?
Triggers differ from person to person and tend to stack. House dust mite, pollen, animal dander and mold act through allergy. Viral colds are the commonest trigger of all, especially in children. Cold air, exercise, smoke, strong smells, pollution and stress irritate airways that are already primed. Aspirin and related painkillers provoke attacks in a distinct subgroup. Severe attacks usually build over hours or days rather than striking without warning, and an attack in which the whistling quietens while breathing grows more labored reflects too little air moving to make the sound rather than any improvement. Asthma attacks are occasionally fatal, which is why severity is judged on how much air is moving and how hard the effort is.
How does it differ from COPD?
| Feature | Asthma | COPD |
|---|---|---|
| Usual onset | Childhood or early adult life | Middle age or later |
| Main driver | Allergy and airway overreactivity | Smoking and other inhaled particles |
| Narrowing | Largely reversible | Persistent, and only partly reversible |
| Course | Episodes with well periods between them | Steady breathlessness with flare-ups |
The two overlap enough that some people carry features of both, and separating them rests on measurement rather than symptoms. A PFT records how much air can be blown out and how fast, before and after a reliever inhaler, and marked improvement supports asthma. Inhaled steroids suppress the inflammation while relievers relax the muscle, and the fixed narrowing of COPD responds far less to that second step. Breathlessness itself, recorded as dyspnea, is common to both.
Also known as
Used in a sentence
Asthma was well controlled on inhaled therapy with no recent exacerbations.
Good to know
Airway narrowing in asthma is largely reversible and the inflammation persists between attacks, so a normal examination or a normal breathing test on a well day does not exclude the condition.
Word origin
Where “asthma” comes from
Asthma comes directly from the Greek asthma, meaning panting or short, labored breathing.