Written by Gary Presant, MD
Monday, 05 October 2009
Asthma is a common 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.
What is going on in the body?
In a person with asthma, the airways narrow as a result of irritation and inflammation. 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 with 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. When the muscles relax, the bronchial tubes open wider. Asthma symptoms then resolve, 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 and 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 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
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 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 tightening of the muscles 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, 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 and nedocromil, which act on the immune system to reduce inflammation
- inhaled or oral corticosteroids, which prevent swelling and irritation of the airways
- leukotriene modifiers, which block the chemicals that start airway inflammation
- long-acting inhaled beta-2 agonists, which help relax the airways
- methylxanthines, 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
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 before symptoms are even felt. Following the treatment plan at this time will often prevent an asthma attack from getting any worse.