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. Symptoms can worsen over time and gradually become more severe in those that do not take medications regularly. Acute “asthma attacks” can occur with exposure to allergens, cold air, or during exercise. In severe cases, these attacks may be fatal if left untreated.
Although the origin of asthma is not entirely clear, experts believe it is caused by a combination of genetic and environmental factors. The most common environmental triggers include allergens such as:
- Animal dander
- Dust mites
In fact, about 70-90% of patients with asthma have seasonal or environmental allergies. Allergic triggers cause the airways to constrict, making it difficult to breathe. These allergens also lead to inflammation of the airway walls and increase mucus production. This further reduces the ability to breathe and generally does not resolve without medication.
Besides allergens, other environmental triggers include:
- Air pollution
- Smoking & second-hand smoke exposure
- cold air inhalation (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. 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).
In the United States approximately 7% of people are living with asthma. It is estimated that over 300 million people in the world have been diagnosed with asthma. It can affect individuals of any age but tends to most commonly present in children and adolescents. Asthma is 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.
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
In individuals who already have asthma, these same risk factors can lead to increased frequency and severity of asthma attacks. Illnesses of any type, surgery, certain medications, and food allergens can all increase the severity of asthma even in a patient with only mild symptoms.
Asthma generally begins with a cough that is worse in the morning or evening following an acute illness. In others it may present during periods of intense exercise or during a bout of seasonal allergies. Symptoms generally progress to include:
- Cough (with thick clear mucus, but may be dry)
- Difficulty breathing
- Chest tightness
In the majority of individuals the symptoms of asthma only occur occasionally, usually with with exposure to the offending trigger. This is known as mild intermittent asthma and is the least severe type.
In other individuals, symptoms will be present constantly unless daily treatment is begun. This is known as persistent asthma. There are three severities of persistent asthma, mild, moderate, and severe. The symptoms are similar in all three, they differ in how resistant they are to treatment and how often symptoms present. In the most severe cases, people with persistent asthma have continuous symptoms that can be debilitating.
All types and severities of asthma can result in an acute asthma exacerbation commonly called an “asthma attack.” An asthma attack will begin with a sudden increase in the usual asthma symptoms. Untreated cases may lead to low oxygen levels, labored breathing, difficulty forming sentences, and wheezing on lung examination. Sometimes asthma attacks are so severe that the lung sounds are barely audible with the stethoscope because there is little (if any) air movement. Severe asthma attacks can lead to death if left untreated.
Your primary care doctor will generally be able to make an initial diagnosis of asthma based on your symptoms and a physical examination. Confirming the diagnosis generally requires advanced testing that will be performed by a lung specialist known as a pulmonologist.
Commonly performed tests include a chest x-ray to get a “picture” of your lungs and ensure that no structural abnormalities or infections are present. 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.
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 and the pneumococcal pneumonia vaccine.
If you have been diagnosed with persistent asthma one of the best ways to avoid asthma attacks is to take your daily medications regularly. The majority of daily asthma medications work best when taken daily over the course of weeks, skipping days of these medications is likely to lead to increased number and severity of asthma attacks.
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 airflow and relieve symptoms. They work by stimulating a receptor known as the beta-2 receptor which dilates the small air passages in the lungs. This is why you may hear them being referred to as “beta-agonists.” 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 to be used once or twice daily. These medications contain a long-acting bronchodilator combined with an inhaled corticosteroid (eg, Advair, Symbicort). They work by both preventing airway constriction and reducing chronic 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.
Asthma exacerbations, commonly called asthma attacks, are a sudden worsening of asthma symptoms in response to an acute trigger. Regardless of the trigger, the treatment is the same. Large amounts of inhaled rescue medications are given by a nebulizer and oral steroids are generally used in addition to the patient’s usual inhaled controller medications to further reduce inflammation. If you begin to experience the sudden onset of cough, shortness of breath, wheezing, and difficulty breathing you should seek medical attention immediately. Follow your physician’s set plan for the self-treatment of mild asthma attacks if one has been created for you.
If you begin to have increasing difficulty breathing despite inhaled medications, begin to feel tired, or have difficulty catching your breath you should seek emergency care immediately.
Mild to moderate asthma attacks are generally treated on an outpatient basis with rescue inhalers, inhaled controller medications, and oral corticosteroids (eg, prednisone) in otherwise healthy individuals.
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 for asthma
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) to reduce inflammation 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.
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