Asthma

Overview

By Tina Shahian, PhD

Asthma is a chronic condition wherein the airways that deliver air to the lungs become swollen and narrowed. Certain substances in the environment act as ”triggers” for increased inflammation and mucus production that further restrict airflow, causing shortness of breath, wheezing, and coughing.

Asthma affects people at any age and can lead to minor symptoms or life-threatening attacks. Although there is no cure, individuals with asthma can treat their symptoms with medication and lead normal lives. Seven million children and over 18 million adults live with asthma in the United States.

Causes and Risk Factors

The exact cause of asthma is not yet understood; however, various environmental and genetic factors are known to play a role. Asthma triggers can lead to symptoms (mild or severe) in those who already have the disease, and they include:

  • Airborne allergens (e.g. pollen and dander)
  • Respiratory infections
  • Air pollution
  • Sulfites and food preservatives
  • Certain medications (e.g. beta blockers and aspirin)
  • Gastroesophageal reflux disease (GERD)
  • Cold air
  • Physical activity
  • Emotional stress.

Asthma risk factors increase a person’s likelihood of developing the disease, and they include:

  • A family history of asthma
  • Smoking or exposure to second-hand smoke (including in utero)
  • Certain allergies (e.g. hay fever)
  • Respiratory infections, especially during infancy
  • Inhaling air pollution or aerosolized chemicals (e.g. hairspray)
  • Obesity.

bronchi within the left lung

 

Symptoms

The following symptoms are associated with an “asthma episode” or “asthma attack”, and may require immediate medical attention:

  • Frequent coughing, especially at night, during sleep, and early morning
  • A whistling or “wheezing” sound when breathing
  • Chest tightness
  • Shortness of breath.

Diagnosis and Treatment

In order to diagnose asthma, a doctor first conducts a physical exam and inquires about the family history of asthma and other known risk factors. Next, various tests are performed to assess the flow of air into the lungs. The following are the main diagnostic tests for asthma:

  • Lung function. Spirometry and peak flow tests measure the amount, rate, and force of exhaled air. This information allows physicians to estimate the extent of narrowing in the airways, as well as patient response to treatment. Improved lung function following medication (e.g. albuterol) or decreased lung function following a clinical trigger (e.g. methacholine) are positive indication of asthma.
  • Allergy testing. This test helps identify the allergens that cause an asthma attack and allows for designing the right treatment plan.
  • Imaging. A visual inspection of the lungs and sinuses using X-ray and high-resolution computerized tomography (CT) scan helps detect infections or other abnormalities.
  • Stress and cold testing. Modified lung function tests that include physical activity or cold inhaled air allow for diagnosis of asthmas that are triggered by these factors.

Asthma treatment requires a lifetime commitment and depends on the severity and frequency of symptoms. Long-term treatments aim to prevent severe asthma attacks, while quick-relief treatments control sudden flare-ups. Treatments are generally delivered via hand-held inhalers or nebulizers that produce a fine mist.

  • Long-term drugs. Inhaled corticosteroids prevent inflammation inside the airways, thereby reducing sensitivity to environmental asthma triggers. Other drugs that work by controlling inflammation are leukotriene modifiers and cromolyn. Theophylline and long-acting beta2-agonists prevent chest tightness by relaxing the muscles that surround the airways. Beta2-agonists are usually administered with corticosteroids as a combination inhaler. Omalizumab is an antibody therapy that helps control allergy-linked asthma.
  • Quick-relief drugs. In instances of a sudden asthma attack, short-acting beta2-agonists quickly alleviate symptoms by opening up the airways. Ipratropium and corticosteroid therapies are used to dilate the airways (bronchodilator) and reduce inflammation, respectively.
  • Other remedies. Allergy-induced asthma is treated with antihistamines or other immunotherapies that reduce the body’s immune response to allergens. Keeping the home environment free of known allergens is also advisable.

Prevention

Although asthma the disease cannot be prevented, asthma attacks can be prevented by taking the required medications and avoiding known triggers. Getting the pneumonia and seasonal flu vaccines also help avoid asthma-related complications. Reducing exposure to cigarette smoke, air pollutants, and harmful aerosolized chemicals, especially during infancy, can lower the risk of developing asthma later in life.

Sources

  • “What is Asthma?” Nation Heart, Lung, and Blood Institute. Jun 2012. Retrieved Jul 10, 2014. http://www.nhlbi.nih.gov/health/health-topics/topics/asthma/.
  • "Asthma". Mayo Clinic. Mayo Foundation for Medical Education and Research. Feb 2014. Retrieved Jul 10, 2014. http://www.mayoclinic.org/diseases-conditions/asthma/basics/definition/con-20026992.
  • "Asthma”. American Lung Association. Retrieved Jul 10, 2014. http://www.lung.org/lung-disease/asthma/.