How Is Severe Asthma Diagnosed?
Your doctor thinks you may have severe asthma. With asthma, the adjective "severe" means your asthma is therapy-resistant, not responding to past or current treatments. You've learned that with this condition you may experience wheezing and coughing, difficulty breathing (often with shortness of breath), and your chest might feel tight.
Symptoms can bother you 24/7, and even doing the simplest tasks or exerting yourself can be a struggle. Your asthma attacks are frequent and can increase during the night. The World Health Organization (WHO) cites poor treatment adherence and persistent triggers as the most common causes of severe asthma. Whatever the cause, your doctor will want to make a definitive diagnosis about the degree of severity of your asthma.
Here's what to expect during the process of a severe asthma diagnosis. Your doctor will:
1. Evaluate your medical history
According to a comprehensive report on severe asthma in the German medical journal, Deutsches Arzteblatt International, these evaluations should include:
- Nature, duration, and triggers of symptoms
- Your age and circumstances when you began having symptoms
- Relationship between your symptoms and both physical activity and your job
- Seasonality and circadian variations (over the 24-hour circadian cycle) in symptoms
- Responsiveness of symptoms to asthma-specific therapies
- Changes of symptoms when you travel
- Active and passive smoking — i.e., you involuntarily inhale second-hand smoke
- Allergies and comorbidities such as rhinitis, sinusitis, obstructive sleep apnea, or gastroesophageal reflux disease
- Family history of asthma or allergic diseases
- Regular contact with animals
- Job or personal stress factors
- Tolerance of cyclooxygenase (COX) 1 inhibitors: anti-inflammatory drugs such as aspirin, ibuprofen and naproxen block the action of (COX)1
- Long-term medication use, adherence, and inhalation technique
- Exacerbations and hospitalizations during the last 12 months
Healthcare professionals indicate that sharing family history of asthma or severe asthma is important. Be willing to proactively share details. Even if saying something about your asthma in the present feels uncomfortable, this is the time to put it all out there. It's smart to make a list of questions and medical details to share before you go to this appointment so you don't forget to ask about what's on your mind. If you've been keeping a symptom diary — which is very helpful — don't forget that. Also, don’t be embarrassed to ask a question again. Remember, this is a lot of information to hear, absorb, and remember. Taking notes or bringing someone along may also be helpful.
2. Perform a clinical exam
Based on a standard exam format offered at Michigan Medicine at the University of Michigan, doctors will likely want to examine your:
- Nose, looking for drainage, swelling inside, and nasal polyps
- Throat, again for drainage, which could indicate sinusitis
- Chest for wheezing, and for signs you use your chest muscles to breathe
- Fingers for absence of an angle at the nail and rounding of the fingertips, a sign of lung diseases
- Skin for allergic conditions such as atopic dermatitis, called eczema; this is associated with increased incidence of allergic rhinitis, food allergy, and asthma.
They also want to:
- Check for rapid or shallow breathing.
- Listen for rapid heartbeat or other signs related to breathing difficulties.
3. Conduct these tests
Blood work: For patients with severe persistent asthma, these tests might be beneficial:
- CBC and differential to evaluate the presence/absence of eosinophils, a type of "combat" white blood cell, and exclude anemia as a cause of dyspnea or shortness of breath.
- Total serum immunoglobulin E (IgE) level for allergic bronchopulmonary aspergillosis ABPA, a form of lung disease that occurs when people are allergic to the fungus, aspergillus; or to identify candidates for anti-IgE therapy, a treatment that interferes with function of the antibody in the immune system called IgE.
Other diagnostics: You may have these diagnostics or may have some of them again:
- Peak expiratory flow: Measures maximum airflow when you perform a forceful exhalation.
- Spirometry: It's a measure of lung function or how fast air is exhaled. It's recommended to do a pre- and post-bronchodilator spirometry with inspiratory and expiratory — breaths in and out — flow loops, lung volumes, and diffusing capacity, the transfer of gas from air in the lung to red blood cells in lung blood vessels.
- Fractional exhaled nitric oxide (FeNO): The test measures this colorless, toxic gas in exhaled breath to assess airway inflammation.
- Airway responsiveness: It evaluates how your airways react to asthma triggers.
- Whole-body plethysmography (in addition to spirometry): It's done with bronchial challenge testing — which evaluates airway sensitivity in the lungs — to measure specific airway resistance.
- Reversibility testing: This distinguishes asthma from other causes of obstructive lung disease. It uses a bronchodilator and spirometer. Bronchodilators open airways and the spirometer measures lung function.
- Imaging: A chest x-ray or high resolution computed tomography (HRCT) may be indicated.
- Sputum counts: A sample of saliva mixed with mucus undergoes laboratory analysis to determine the root of airway inflammation.
- Using specific phenotype testing
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