Asthma

Long-term lung disease

Basic Information

What is Asthma?

Asthma is a lung condition characterized by episodes of obstructed breathing. They occur due to narrowing of the breathing passages, making it difficult to inhale but even more difficult to exhale. The narrowing can be caused by inflammation in the airways, by spasm of the muscles in the airways (bronchospasm), or both.

Asthma can be acute or chronic. With acute asthma, the airways are relatively normal between attacks. In chronic asthma there is some narrowing of the airways continuously, with further narrowing during an acute attack. Asthmatic episodes are experienced as tightness in the chest, difficulty exhaling, wheezing, and coughing. An asthma attack can last minutes or days, and can range from mild to life threatening. The unpredictability of these episodes can make them extremely frightening for the individual and the family. Between attacks, the individual's lung function may be entirely normal. Precipitating factors for an attack can be viral respiratory infections, allergy, smoke or air pollution, a drug such as aspirin or beta-blockers, a specific food or food additive such as sulfites), physical exertion especially in cold air, and emotional stress. Occupational asthma can be seen when the causative agent is found in the work place, perhaps from dusts, molds, chemical fumes, metals, or exposure to animals or their dander.

Approximately five percent of the US population has asthma, and the incidence appears to be rising in the industrialized world. Susceptibility to asthma appears to be an inherited trait. Most cases begin before the age of 25, but asthma can begin at any age. Being born prematurely increases the risk of developing asthma later.

Causes

Inflammation and resulting spasm of air passages (bronchi
and bronchioles), followed by swelling of the passages and
thickening of lung secretions (sputum). This decreases or
closes off air to the lungs. These changes are caused by:

Preventive measures

Take prescribed preventive medicines regularly; don't
omit them when you feel well.

Avoid aspirin.

Investigate and avoid triggering factors.

Do relaxation and airway clearing exercises.

Expected outcomes

A pneumothorax or pneumomediastinum can occur with severe asthma attacks, especially if the individual requires mechanical ventilation. In a severe asthma attack that is unresponsive to treatment, a state of prolonged bronchospasm called status asthmaticus can result; this may be followed by respiratory failure and death. Individuals with chronic pulmonary disease in addition to asthma will often have more severe and debilitating episodes of asthma. Asthmatics being treated with long-term steroids can have the complications of blood chemistry disturbances, cataracts, immunosuppression, and adrenal suppression. Cardiac arrhythmia may be precipitated by over-treatment for asthma.

Possible complications

The outcome in asthma is quite variable. Nearly twenty percent of people with asthma have some limitation in their daily life due to the disease. A mild asthmatic attack may be treated easily with an extra dose of inhaled bronchodilator. A severe asthmatic attack developing over weeks might lead to status asthmaticus, hospitalization, and multiple complications. If the individual's airways remain chronically inflamed, chronic bronchitis can result, leading to permanent disability.

Asthma treatment

General measures

Diagnostic tests may include laboratory blood studies,
pulmonary-function tests and allergy testing, usually with
skin tests.

Emergency-room care and hospitalization for severe
attacks.

Psychotherapy or counseling, if asthma is stress-related.

Eliminate allergens and irritants at home and at work, if
possible. Treatment for desensitizing to specific allergens.

Acute asthma is treated with an inhaled bronchodilator and oxygen. Intravenous muscle relaxants and steroids may also be needed. If the attack is severe and prolonged, the individual is admitted to the hospital for intensive treatment, as respiratory failure can be a possible development. Treatment might require a positive-pressure oxygen mask or a mechanical ventilator.

Treatment of chronic asthma includes inhaled bronchodilators, as well as decreasing the exposure to causative agents. In persons with more frequent and/or severe attacks, use of inhaled steroids, mast cell stabilizers, muscle relaxants, and oral steroids may be prescribed long-term. Aggressive treatment of pulmonary infections is recommended, along with immunization against influenza and pneumococcal pneumonia.