Asthma is a lung disease that causes repeated bouts of wheezing, shortness of breath, chest tightness, and coughing, especially at night or in the early morning. A person with asthma has difficulty breathing because of inflammation and narrowing of the airways.
Asthma is one of the most common long-term diseases; according to the Asthma and Allergy Foundation of America, about 20 million people in this country have asthma. In recent years, the proportion of people with the condition has been gradually increasing, for reasons that are not fully known.
What is going on in the body?
In a person with asthma, the airways narrow as a result of irritation, inflammation and increased secretions. During an asthma flare-up or "asthma attack," muscles of the airway tubes, or bronchi, tighten. The reaction in the lungs is out of proportion to the amount of stimulation experienced. The inflammation and tightening in the airways increases, trapping air in the lungs. The overreaction to the trigger causes excess mucus to form in the lungs. The person cannot take in a full breath and feels short of breath.
Sometimes the reaction to the trigger causes swelling throughout the entire bronchial tube. The opening in the center of the tube then becomes smaller, and breathing becomes more difficult. Asthma symptoms resolve when the airway opens back up, and breathing becomes easier.
What are the causes and risks of the disease?
Asthma is caused by an immune system response. The immune system overreacts to triggers and causes the airways to become inflamed and tight. Often there are provoking factors, or triggers, that cause asthma symptoms. Triggers differ from person to person. Asthma triggers include:
- allergies to food such as peanuts or to foods with sulfites, such as beer, wine, processed foods, and shrimp
- cold, dry air and wind
- dust and dust mites
- hormonal changes resulting from pregnancy or menstruation
- indoor and outdoor pollution from exposure to fumes, paint, fireplace smoke, or perfume
- medicine allergies
- pets with fur or feathers
- smoke inhalation
- viral infections, such as a cold or flu
What can be done to prevent the disease?
There are no immunizations or other treatments that can prevent asthma, but some measures can help to prevent flare-ups of asthma. Once an individual has been diagnosed with asthma, the healthcare provider will recommend a treatment plan. The plan usually includes identifying and avoiding any triggers and taking allergy shots or medicines. By following the treatment plan, an individual can minimize asthma flare-ups.
How is the disease diagnosed?
Diagnosis of asthma begins with a medical history and physical exam. Pulmonary function tests are simple breathing tests that measure how well air travels through the airways and how much air the lungs can hold. Chest X-rays can show air trapped in the lungs.
Sometimes a person has symptoms of asthma, but shows normal results on pulmonary function tests. In this case, the healthcare provider may order another test to increase the demand on the lungs and try to provoke symptoms of asthma. A medicine such as methacholine may be used for this purpose. Alternatively, the person may be asked to walk on a treadmill or do some other form of exercise. When the lungs are working their hardest, pulmonary function tests may then be able to detect airway problems.
Long Term Effects
What are the long-term effects of the disease?
Asthma is characterized by periodic flare-ups. Between flare-ups, many people will have a return to normal breathing. Over many years, this pattern can continue without the person getting dramatically worse. In some people, asthma flare-ups increase as they get older.
In people with more severe asthma, long-term inflammation can lead to permanent changes in the airways. This is called airway remodeling. The actual structure of the airway walls can change, causing blockage that cannot be completely reversed with treatment.
Sometimes asthma symptoms wane or even disappear as children grow up.
What are the risks to others?
Asthma is not contagious and poses no risk to others.
What are the treatments for the disease?
Successful treatment of asthma involves two important factors:
- avoiding known irritants or triggers
- taking medicines to reduce airway inflammation and to treat flare-ups
Avoiding known irritants is key to controlling asthma. Avoid anything that one can see or smell in the air, especially cigarette smoke, dust, and strong chemical odors. Many people with asthma also have allergies. Allergic reactions can trigger an asthma flare-up. Avoiding things that cause the allergies, called allergens, is important. Controlling allergies with appropriate medicine or allergy shots can often improve asthma symptoms.
Medicines for treatment of asthma include both quick-relief and long-term-control medicines. The healthcare provider will prescribe the appropriate medicines for each individual. In general, the following principles are used:
- people who have asthma symptoms only intermittently are given quick-relief medicines
- people with persistent asthma are often given both quick-relief and long-term-control medicines
- people with exercise-induced asthma symptoms may be told to take quick-relief or long-term-control medicines right before exercise
Quick-relief medicines work within minutes. They prevent or help reduce the narrowing of the bronchial tubes. They are used when a person experiences an asthma attack or sudden shortness of breath.
Short-acting beta-2 agonists, such as albuterol, and short-acting anticholenergic agents such as ipratropium (Atrovent) are used for quick symptom relief. These medicines are usually taken through a metered dose inhaler or nebulizer.
Long-term-control medicines are taken on a regular basis to calm the airways and prevent symptoms. They are not effective for quick relief during an asthma attack. These medicines include:
- cromolyn (i.e. Intal) and nedocromil (i.e., Tilade), which act to reduce inflammation
- inhaled corticosteroids (i.e., AeroBid, Azmacort, Flovent, Pulmicort) or oral corticosteroids (i.e. prednisone), which prevent swelling and irritation of the airways
- leukotriene modifiers (i.e., montelukast or zafirlukast ), which block the chemicals that start airway inflammation
- long-acting inhaled beta-2 agonists (i.e., salmeterol (Serevent) or formeterol (Fordil), which help relax the airways
- long-acting anticholenergic agents like tiotropium (i.e., Spiriva) also relax the airways
- methylxanthines (i.e., theophylline ), which relax the airway muscles
What are the side effects of the treatments?
Short-acting beta-2 agonists and anticholinergics may cause the following side effects:
- dry mouth and difficulty speaking
- high blood pressure
- racing heartbeat
- shakiness or tremors
Corticosteroids have fewer side effects when given by inhaler than when they are taken orally. Side effects may include:
- bone thinning
- change in voice tone
- growth problems in children
- muscle weakness
- oral thrush, a yeast infection in the mouth
- weight gain
Long-acting beta-2 agonists may cause the following side effects:
- difficulty sleeping
- dry mouth
- feeling nervous or shaky
Leukotriene modifiers may cause:
- abdominal pain and diarrhea
- nausea and vomiting
- sore throat
Methylxanthines may cause:
- difficulty sleeping
- irritability and shakiness
- nausea and vomiting
Cromolyn and nedocromil may cause:
- a bad taste in the mouth
- chest tightness
What happens after treatment for the disease?
Effective treatment of asthma reduces inflammation and tightening of the airways, lowering the frequency of asthma attacks. Successful treatment allows people with asthma to enjoy life without significant breathing problems.
How is the disease monitored?
A person with asthma can monitor breathing at home with a device called a peak flow meter. Some people use peak flow meters every day and keep a record in their asthma diary. Airway changes show up on a peak flow meter often before symptoms are even felt. Following the treatment plan at this time will often prevent an asthma attack from getting any worse.
Periodic pulmonary function testing can help guide the healthcare provider in prescribing medicines. Any new or worsening symptoms should be reported to the healthcare provider.