What is Asthma?
Asthma is a highly prevalent lung disease characterized by airway constriction and inflammation. It is one of the most common conditions evaluated and treated in primary care clinics around the world.
Individuals usually experience episodes of difficulty breathing, wheezing, and cough. In serious cases, attacks may be fatal if left untreated.
What Causes Asthma?
Although the origin is not entirely clear, experts believe it is caused by a combination of genetics and environmental factors. The most common environmental triggers include allergens such as:
- Animal dander
- Dust mites
- Cock roaches
In fact, about 70-90% of patients with asthma have allergies. Allergic triggers cause the airways to constrict, making it difficult to breath. The airways also become inflamed and release increasing amounts of mucous, which makes breathing even more challenging.
Besides allergens, other environmental triggers include:
- Air pollution
- Smoking & second hand smoke exposure
- Inhalation of cold air (cold-induced asthma)
Conditions such as acid reflux and viral or bacterial infections can also provoke symptoms. For example - the common cold, upper respiratory infections, and pneumonia commonly aggravate asthma.
Believe it or not, exercise can also provoke asthma symptoms, especially in children and adolescents. It may even be activated by medications such as aspirin and beta blockers (eg, metoprolol).
How Common is Asthma?
According to studies, it is estimated that about 7% of Americans currently have asthma. In addition, a staggering 300 million people are affected around the world.
It appears to be more common in industrialized countries such as the United States, Canada, and the United Kingdom, possibly due to the higher rates of pollution in these nations. Furthermore, this condition can affect nearly any age group ranging from children to the elderly.
What are the Risk Factors for Asthma?
There are a number of factors that increase your risk of developing asthma, including:
- Family history – having blood relatives with asthma
- History of allergies
- Being overweight or obese
- Smoking & exposure to secondhand smoke
- Fume or chemical exposures at work
Signs and Symptoms
Symptoms usually occur in recurrent episodes or attacks and are provoked by triggers (eg, allergens, smoke, etc). Some people with persistent asthma have continuous symptoms that can be debilitating. Symptoms are typically worse at night or early in the morning. The most common symptoms include:
- Difficulty breathing
- Chest tightness
The cough in asthmatic patients is frequently productive of thick, clear mucus, but may occasionally be dry. Severe cases lead to low oxygen levels, labored breathing, difficulty forming sentences, and wheezing on lung examination. Sometimes asthma is so severe that lungs sounds are barely audible with the stethoscope because there is little (if any) air movement. As mentioned, very severe asthma attacks can lead to death if left untreated.
Your doctor can usually diagnose asthma based on your symptoms and physical examination. Sometimes, when the diagnosis is not clear, they will order tests to help confirm the diagnosis.
Commonly performed tests include a chest x-ray to get a “picture” of your lungs and exclude any structural abnormalities. In addition, your doctor will likely obtain breathing tests to measure lung volumes and assess how well your lungs function.
Breathing tests may be performed before and after receiving a rescue inhaler to see if your lung function improves with treatment. Sometimes, you will be asked to inhale a chemical called methacholine, which constricts the airways and mimics an asthma attack.
How to Prevent an Asthma Attack?
The prevention of asthma attacks involves avoiding triggers such as allergens, smoke, and cold air exposure. It is also critical to receive proper immunizations against certain viruses and bacteria. As discussed earlier, infections such as the flu and pneumonia frequently provoke asthma attacks. Therefore, most people with asthma should receive an annual influenza vaccination, in addition the pneumococcal pneumonia vaccine.
Asthma Medication and Treatment
The first-line treatment of asthma includes the use of rescue inhalers, which are used as needed (every 4-6 hours) for shortness of breath. These medications work by opening up or dilating your airways to promote air flow and relieve symptoms. Examples of rescue inhalers include:
- Ventolin (salbutamol)
- Proair (albuterol)
- Atrovent (ipratropium)
- Combivent (combination of albuterol and ipratropium)
If your symptoms occur frequently and you use your rescue inhaler more than twice a week, your doctor may prescribe an inhaled controller medication once or twice daily. These medications contain a long acting bronchodilator combined with an inhaled corticosteroid (eg, Advair, Symbicort). They work by preventing airway constriction and reducing inflammation – the two cardinal features of asthma.
Patients with severe allergies may also receive allergen immunotherapy or treatment with a drug called omalizumab. Other less commonly prescribed medications include theophylline and zileuton.
Mild to moderate asthma attacks are generally treated on an outpatient basis with rescue inhalers, inhaled controller medications, and oral corticosteroids (eg, prednisone) at times.
Severe asthma exacerbations (and some moderate exacerbations) usually require a visit to the emergency department and may warrant hospital admission. This is particularly true for individuals with high-risk features:
- Very young or elderly patients
- Immunocompromised status – receiving chemotherapy, history of AIDS
- Underlying lung or heart disease
- Previous breathing tube placement
Patients with moderate to severe exacerbations and low oxygen levels typically receive supplemental oxygen through a nasal cannula or face mask. They are also given intravenous corticosteroids (eg, Solumedrol) and nebulized (mist inhaled) treatments with albuterol or Combivent. Very severe cases can cause respiratory failure and may require breathing tube placement and a machine to assist with breathing.
- Kim H, Mazza J. Asthma. Allergy Asthma Clin Immunol. 2011 Nov 10;7 Suppl 1:S2. - https://aacijournal.biomedcentral.com/articles/10.1186/1710-1492-7-S1-S2
- Gibson PG, Powell H. Written action plans for asthma: an evidence-based review of the key components. Thorax. 2004 Feb;59(2):94-9. - https://thorax.bmj.com/content/59/2/94
- Shepherd J, Rogers G, Anderson R, et al. Systematic review and economic analysis of the comparative effectiveness of different inhaled corticosteroids and their usage with long-acting beta2 agonists for the treatment of chronic asthma in adults and children aged 12 years and over. Health Technol Assess. 2008 May;12(19):iii-iv, 1-360. - https://www.ncbi.nlm.nih.gov/pubmed/18485271
- Fanta C. Asthma. N Engl J Med. 2009 March 5; 360:1002-1014. - https://www.nejm.org/doi/full/10.1056/NEJMra0804579
- Subbarao P, Mandhane P, Sears M. Asthma: epidemiology, etiology and risk factors. CMAJ. 2009 Oct 27; 181(9): E181–E190. - https://www.ncbi.nlm.nih.gov/pubmed/19752106
The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.