Asthma

Asthma occurs because the airways in the lungs overreact to various stimuli, resulting in narrowing with obstruction to air flow. This recurrently results in one or more of the following symptoms:

Tightness in the chest

Labored breathing

Coughing

Noises in the chest heard particularly during a prolonged forced expiration (wheezing). As a result of these symptoms, asthmatics may not tolerate exertion. They may be awakened frequently at night. More severe symptoms may result in requirements for urgent medical care and hospitalization. For a very few with particularly severe asthma, there is a risk of fatality.

Asthma affects the airways, which begin just below the throat as a single tube called the trachea. The trachea is situated immediately in front of the esophagus, the passageway that connects the throat with the stomach. The trachea divides into two slightly narrower tubes called the main bronchi (each one is called a bronchus). Each main bronchus then divides into progressively smaller tubes - the smallest are called bronchioles - to carry air to and from microscopic air spaces called alveoli. It is in the alveoli that the important work of the lung occurs, exchanging oxygen in the air for carbon dioxide in the blood. The airways (trachea, bronchi, bronchioles) are surrounded by a type of involuntary muscle known as smooth muscle.

The airways are lined with a mucus membrane that secretes a fine layer of mucus and fluid. This mucus washes the airways to remove any bacteria, dirt, or other foreign material that might get into our lungs. The overreaction or hyper-responsiveness of the airways results in bronchospasm, which is excessive contraction or spasm of the bronchial smooth muscle. The airways also become inflamed with swelling of the bronchial mucous membrane (mucosa) and secretion of excessive thick mucus that is difficult to expel. It is part of the evaluation process to identify the role of each of these physiologic components in asthma. This is important because bronchospasm (constriction of the muscle surrounding the airways) and inflammation respond to different medications.

Image of a normal bronchiole and an asthmatic bronchiole

The airway hyper-responsiveness leading to obstruction of the airways occurs from one or more of various stimuli that vary with the individual patient. These include:

Viral (but not bacterial) respiratory infections (common colds)

Inhaled irritants (cigarette smoke, wood burning stoves and fireplaces, strong odors, chemical fumes)

Inhaled allergens (pollens, dusts, molds, animal danders)

Cold air

Exercise

Occasional ingested substances (aspirin, sulfite preservatives, specific foods). Sometimes these exposures just act as triggers of brief symptoms with rapid relief once exposure ends. Sensitivity of the airway may be increased, however, following even brief exposure to one of these. This causes a longer period of asthmatic symptoms. More information should be provided to you for each of these that are judged to be important for your asthma.

The obstruction of the airways decreases the rate at which air can flow. This is felt as tightness in the chest and labored breathing (dyspnea). The obstruction and inflammation causes coughing. Obstruction to air flow can be measured with pulmonary function tests, which can detect even degrees of airway obstruction not yet causing symptoms. Pulmonary function measurements can be an extremely valuable tool for your physician to make decisions regarding treatment.

The increased mucus in the airways stimulates coughing as the body attempts to clear the airways. The unusually thick (viscous) mucus is difficult to expel, however, resulting in continued coughing that fails to adequately expel the mucus. General irritability of the airways also causes coughing. The coughing and mucus production may cause some physicians to diagnose bronchitis. However, the term "bronchitis" simply means inflammation of the airways, and asthma causes airway inflammation. Consequently, anti-asthmatic medication, and not antibiotics, are the appropriate treatment. (Of course an asthmatic can, on occasion, have an infectious bronchitis that does not respond to anti-asthmatic medication, but this is usually viral and usual antibiotics are still not generally of any value - although there are exceptions to this generality).

Narrowing of the airway causes noises when air passes through them with sufficient speed. This typical high-pitched noise is called wheezing. Mucus in the airway causes a rattling sound called coarse crackles. Complete obstruction of some airways can cause absorption of air from the alveoli (air sacks at the end of the airways in the lungs). This causes portions of the lung to appear more dense and cast more of a shadow on a chest x-ray (this is called atelectasis). The rattling sounds or increased shadows on the x-ray are often misinterpreted as indicating pneumonia. The inappropriate diagnoses of bronchitis and pneumonia cause much unnecessary use of antibiotics, which are ineffective both for asthma in general and for most of the infections, such as the common cold viruses, that trigger asthma.

People with asthma usually have obvious symptoms. These signs and symptoms resemble many respiratory infections:

Chest tightness, pain or pressure.

Coughing (especially at night).

Shortness of breath.

Wheezing.

With asthma, you may not have all of these symptoms with every flare. You can have different symptoms and signs at different times with chronic asthma. Also, symptoms can change between asthma attacks.

Researchers don’t know why some people have asthma while others don’t. But certain factors present a higher risk:

Allergies: Having allergies can raise your risk of developing asthma.

Environmental factors: People can develop asthma after exposure to things that irritate the airways. These substances include allergens, toxins, fumes and second- or third-hand smoke. These can be especially harmful to infants and young children whose immune systems haven’t finished developing.

Genetics: If your family has a history of asthma or allergic diseases, you have a higher risk of developing the disease.

Respiratory infections: Certain respiratory infections, such as respiratory syncytial virus (RSV), can damage young children’s developing lungs.

You can have an asthma attack if you come in contact with substances that irritate you. Healthcare providers call these substances “triggers.” Knowing what triggers your asthma makes it easier to avoid asthma attacks.

For some people, a trigger can bring on an attack right away. For other people, or at other times, an attack may start hours or days later.

Triggers can be different for each person. But some common triggers include:

Air pollution: Many things outside can cause an asthma attack. Air pollution includes factory emissions, car exhaust, wildfire smoke and more.

Dust mites: You can’t see these bugs, but they are in our homes. If you have a dust mite allergy, this can cause an asthma attack.

Exercise: For some people, exercising can cause an attack.

Mold: Damp places can spawn mold, which can cause problems if you have asthma. You don’t even have to be allergic to mold to have an attack.

Pests: Cockroaches, mice and other household pests can cause asthma attacks.

Pets: Your pets can cause asthma attacks. If you’re allergic to pet dander (dried skin flakes), breathing in the dander can irritate your airways.

Tobacco smoke: If you or someone in your home smokes, you have a higher risk of developing asthma. You should never smoke in enclosed places like the car or home, and the best solution is to quit smoking. Your provider can help.

Strong chemicals or smells. These things can trigger attacks in some people.

Certain occupational exposures. You can be exposed to many things at your job, including cleaning products, dust from flour or wood, or other chemicals. These can all be triggers if you have asthma.

Family history. If you have a parent with asthma, you are three to six times more likely to develop asthma than someone who does not have a parent with asthma.

Viral respiratory infections. ...

Allergies. ...

Occupational exposures. ...

Smoking. ...

Air Pollution. ...

Obesity.

Some of the complications of asthma include insomnia, fatigue, physical inactivity and weight gain, the flu, mental health conditions, pneumonia, obstructive sleep apnea, and side effects from medication. In some cases, untreated asthma can lead to hospitalization, respiratory failure, and death.

Signs and symptoms that interfere with sleep, work and other activities.

Sick days from work or school during asthma flare-ups.

A permanent narrowing of the tubes that carry air to and from your lungs (bronchial tubes), which affects how well you can breathe.

If your healthcare provider says you have asthma, you’ll need to figure out what triggers an attack. Avoiding the triggers can help you avoid an attack. You can’t prevent yourself from getting asthma, though.

Follow your asthma action plan. ...

Get vaccinated for influenza and pneumonia. ...

Identify and avoid asthma triggers. ...

Monitor your breathing. ...

Identify and treat attacks early. ...

Take your medication as prescribed. ...

Pay attention to increasing quick-relief inhaler use.