Definition of Asthma

asthma

Asthma is a disease of the airways that results in narrowing of the airways (bronchospasm) and inflammation in response to a wide range of inhaled irritants such as pollen, mold, smoke, chemicals, and the airborne debris of pests ranging from cockroaches to microscopic dust mites.

This narrowing, or airflow obstruction, is usually reversible when the person can eliminate the exposure or through treatment with medications called bronchodilators.

Repeated exposure to irritants in susceptible people can result in repeated episodes of inflammation. This pattern can ultimately cause scarring of the airways that is not reversible.

Nearly 18 million Americans have asthma, a third of whom are under age 18. For many of them asthma attacks are mild and infrequent, giving the perception that asthma is a common and, though annoying, harmless condition.

However, lifethreatening consequences can occur during a severe asthma attack. If the person does not receive rapid and effective treatment, the airway narrowing and inflammation can completely block the flow of air. The person cannot exhale (breathe out) fully, lowering oxygen levels and potentially causing death. Nearly 5,000 Americans die each year as a consequence of asthma or its complications.

Signs and Symptoms and Diagnostic Path

An asthma attack generally follows a pattern of symptoms that, though it varies among people who have asthma, tends to be consistent for each individual. Some people first experience dyspnea (shortness of breath) or wheezing (a high-pitched whistling sound with exhalation), for example, while other people find a restless night with frequent waking foreshadows an asthma attack that manifests the following day. Common symptoms of asthma attacks include

  • Dry, nonproductive cough
  • Sense of tightness in the chest
  • Dyspnea, especially during physical activity
  • Wheezing
  • Gasping for air

There are no definitive tests for asthma. The diagnostic path may include tests and procedures, such as chest X-RAY and complete blood count (CBC), to rule out other causes of symptoms. The pulmonologist will conduct pulmonary function tests to measure the flow and volume of air, typically before and after administration of a bronchodilator medication that relaxes and opens the airways.

People who have asthma generally have much improved pulmonary function test results after the bronchodilator, even when they are having no symptoms of asthma at the time of testing. However, the reverse can also be true and the person has normal breathing tests during a time of no symptoms. In such cases, the pulmonologist may conduct a test called a methacholine challenge, administering the DRUG methacholine to see whether it initiates a mild hypersensitivity reaction. A positive response (symptoms appear) is fairly conclusive of an asthma diagnosis.

Asthma Classification

CLASSIFICATION
ClassificationSeverityFrequency of Symptoms Without Treatment
step 1mild intermittentsymptoms occur two days or less each week and two nights or less each month
step 2mild persistentsymptoms occur up to five days each week and up to five nights in a month
step 3moderate persistentsymptoms occur at least once during every day and several nights a week
step 4severe persistentsymptoms occur throughout the day, every day, and most nights

Treatment Options and Outlook

Treatment for many people who have asthma is a combination of medications to prevent symptoms (long-acting, controller medications) and to provide immediate relief from symptoms that occur (short-acting, rescue medications). Medication regimens vary with the step (classification) and nature of symptoms. Commonly prescribed medications include

  • Inhaled (and occasionally oral) corticosteroid medications, which are anti-inflammatory and serve as long-term controller medications
  • Inhaled and oral beta-2 agonists, which are bronchodilators and may provide short-acting or long-acting relief
  • Leukotriene modifiers, which are immune response mediators that provide long-term control

The mainstay of asthma treatment is baseline control of the inflammation with long-acting medications. For some people, allergy desensitization (when allergy reaction is the clear cause of the asthma) provides further control. Other important steps for managing asthma long-term include monitoring asthma symptoms (such as with peak flow monitoring) and developing an action plan for asthma control.

When there is an acute exacerbation of symptoms (an asthma attack), treatment is most likely to succeed when it begins in advance of or immediately on recognition of symptoms. Once an asthma attack is under way, even rescue medications may take time to bring the situation under control.

Lifestyle factors for managing asthma include avoiding known triggers and allergens. Three of the most common triggers are allergic rhinitis, chronic sinusitis, and gastroesophageal reflux disorder (gerd). Regular physical exercise, though for some people a trigger for asthma attacks, generally improves lung capacity, pulmonary efficiency, and aerobic fitness.

Air-conditioning helps reduce humidity in the air and filter the air of particulates that may cause irritation or exacerbate asthma symptoms. It is important to regularly change the air filters for central heating and cooling systems. acupuncture treatments are helpful for reducing the frequency and severity of asthma attacks in some people.

Medications to Treat Asthma

MEDICATIONS
Type of MedicationCommon ProductsType of ReliefAsthma Classification
beta-2 agonists, inhaledalbuterol (Airet, Proventil, Ventolin), bitolterol (Tornalate), pirbuterol (Maxair)short-acting
rescue
steps 1, 2, 3, or 4
beta-2 agonists, orallong-acting: salmeterol (Serevent), albuterol extended release (Volmax, Proventil Repetabs)
short-acting: terbutaline (Brethine, Bricanyl)
long-acting: controller medication, especially at night
short-acting: rescue
steps 2, 3, and 4
corticosteroids, inhaledbeclomethasone (Qvar, Vanceril), budesonide (Pulmicort), flunisolide (AeroBid), fluticasone (Flovent), triamcinolone (Azmacort)long-acting
controller medication
steps 2, 3, and 4
corticosteroids, oralmethylprednisolone (Medrol), prednisone (Deltasone, Orasone), prednisolone (Prelone)short-acting
controller medication for symptoms that do not respond to other medications
rescue
steps 3 and 4
leukotriene modifiers, oralzafirlukast (Accolate), zileuton (Zyflo)long-acting
controller medication
steps 3 and 4, occasionally step 2
other, inhaledipratropium (Atrovent), cromolyn (Intal), nedocromil (Tilade)short-acting
rescue
prophylactic when used before intense physical exercise
steps 3 and 4
other, oraltheophylline (Theo-Dur, Theolair, Aerolate, Slo-Phyllin)long-actingstep 3, occasionally step 2

Risk Factors and Preventive Measures

The key risk factor for asthma attack is exposure to a substance that initiates a hypersensitivity reaction. Most people can easily identify these substances after experiencing a few asthma attacks, and avoiding exposure to known allergens significantly reduces attacks. A wide range of irritants can cause asthma attacks in many people, however, making it impossible to avoid exposure. As well, for some people triggers for asthma attacks include emotional stress and physical exertion, common elements of everyday life.

Health experts have identified a number of factors that appear to increase an individual’s risk for developing asthma. Key among them are

  • living in cities, where the concentration of particulate pollutants in the air is high
  • family history of asthma
  • recurrent upper respiratory infection as a child
  • cigarette smoking or exposure to environmental cigarette smoke
  • long-term or repeated exposure to chemicals such as cleaning solutions, paints, industrial chemicals used in manufacturing, pesticides and herbicides, and aerosols
  • presence of allergic rhinitis, atopic dermatitis, or chronic sinusitis

Viral infections, physical exertion such as with exercise, cold air, sulfite preservatives (common in some foods), some medications, and gastroesophageal reflux disorder (gerd) also may trigger asthma attacks. Researchers do not know why some people develop hypersensitivity reactions to certain substances while other people, even though their immune systems similarly create antibodies, experience normal reactions. Though researchers believe there are likely genetic factors that underlie allergies, they have yet to isolate them.

See also ALLERGIC ASTHMA; ANTIBODYBREATH SOUNDSHYPERSENSITIVITY REACTIONLIVING WITH CHRONIC PULMONARY CONDITIONSMULTIPLE CHEMICAL SENSITIVITY SYNDROME.

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