Asthma is a chronic (ongoing) inflammation of the body’s bronchial (airway) tissues that afflicts millions of people in the United States. People with asthma experience symptoms such as:

• Wheezing
• Shortness of breath (dyspnea)
• Cough (often at night)
• Exercise-induced wheezing and dyspnea
• Variable airflow obstruction

Researchers have also gained increasing insight into the physiological makeup of asthma. In the 1950s and 1960s, the presence of bronchoconstriction (narrowing of the airway) became an acknowledged feature of asthma. In the next few decades, researchers began to note the important role that airway hyperresponsiveness (AHR) (an exaggerated airway response) and inflammation played in asthma.

Despite everything the healthcare community knows about asthma, to date there remains no single physiologic test that conclusively determines whether or not a person has the condition. Instead, healthcare providers rely on reports of symptoms and various tests before concluding that asthma is the likely source of an individual’s breathing problems. In many cases, a physician cannot make an asthma diagnosis until other diseases have been ruled out.

Several other lung diseases may cause similar symptoms or are otherwise related to asthma. These include:

• Chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis
  
  
• Cardiac asthma
  
  
• Bronchitis (chronic and acute)
  
  
• Bronchiectasis
  
  
• Cystic fibrosis
  
  
• Vocal cord dysfunction
  
  
• Congenital heart disease
  
  
• Bronchopulmonary dysplasia
  
  
• Primary immunodeficiency 
  
  
• Upper airway disease

Sometimes, a healthcare provider will have relatively little trouble accurately diagnosing asthma or another lung disease. For example, most of the time, (COPD) can be ruled out in young patients. Conversely, COPD is a likely diagnosis in a person middle-aged or older who has a long history of smoking and the typical symptoms associated with the disorder.

However, an accurate diagnosis can be difficult for patients who have symptoms common to both COPD and asthma, but do not have symptoms unique to one condition or the other. This is true for other lung disorders as well. Wheezing, chest tightness and shortness of breath are symptoms not only of asthma, but of acute viral infections as well.

Asthma is a more likely diagnosis when the following factors are present:

• Typical symptoms such as cough, wheezing and breathing problems
  
  
• Family history of asthma, allergic rhinitis, atopic dermatitis and/or eczema
  
  
• Patient history of exposure to triggers such as pet dander, cockroaches and tobacco smoke.

A key feature of asthma is airway blockage and inflammation that can be reversed through treatment. Tests that can be used to help confirm the presence of asthma include pulmonary function tests, with spirometry (lung measurement) and assessment of airway responsiveness using methacholine or histamine (bronchoprovocation test). Physicians may also perform other tests, including imaging tests (e.g., chest x-ray) and blood tests, to rule out other conditions.

Once diagnosed, asthma is a highly treatable condition. Various asthma medications, including bronchodilators, corticosteroids and leukotriene modifiers, are available to help prevent asthma attacks, or treat them once they have begun. Asthmatics can also modify their environment and day-to-day behavior in ways that reduce the likelihood of an asthma attack.