Pulmonary

Asthma: Diagnosis and Classification

CLINICAL ACTIONS:

Asthma is a common lung disorder in which inflammation causes the bronchi to swell and narrow the airways (bronchospasm), causing reversible, recurrent airway obstruction. History and physical are important, not only for making the diagnosis but also to help guide classification which is essential for the management plan. Spirometry should be used in all patients >5 years of age to determine that airway obstruction is at least partially reversible.

History: Key Elements

Wheezing
Shortness of breath
Difficulty breathing
Chest tightness
Coughing: Note associated timing
- At night
- During exercise
- When laughing or crying
Symptoms may interfere with normal activities
Ask about aggravating environmental factors such as
- Viral infection
- Animals with fur or hair
- Mold
- Smoking
- Pollen
- Menstrual cycle

Physical Exam

Auscultation: Listen for the following especially when exhaling
- Wheezing
- Whistling
Other clinical findings: Include assessment of the following
- ENT: Ears, nose, throat for swelling, drainage due to allergy and/or inflammation
- Chest: Hyper expansion of thorax (especially children)
- Skin and eyes: Atopic dermatitis | Eczema | Evidence of allergic condition

Pulmonary Function Tests

Spirometry

Test used for both diagnosis and monitoring
Normal score: ≥80 % of predicted value
- Tests the forced expiratory volume of air that can be exhaled during forced breath
  - FEV1 (forced expiratory volume): Volume exhaled in the first second
  - FVC (forced vital capacity): Total volume exhaled after a deep breath
  - FEV1/FVC ratio: When FEV1 <80% of FVC, suspicious for obstructive rather than restrictive lung disease (more likely to decrease proportionally)
  - If FEV1 ≥12% after bronchodilator challenge indicative of reversible airway obstruction

Fractional Exhaled Nitric Oxide (FeNO)

FeNO testing measures the nitric oxide, a byproduct of inflammation, in exhaled breath
May be useful in diagnosing, managing and predicting future exacerbations in some types of asthma
May be used as an adjunct to the evaluation process

Notes: FEV6 (volume after 6 seconds) can be considered rather than FVC in adults for whom full exhalation may take several seconds and be associated with light headedness | There are contraindications to spirometry (e.g., unstable cardiac disease or recent MI, aneurysms, recent thoracic or abdominal surgery, active viral infection, unexplained hypertension) | pre and post bronchodilator testing may be done in pulmonologist practice

Allergy Testing for precipitating factors

Consider referral for allergy testing if possibility that patient has allergies which may precipitate asthma (e.g., cats, dogs, medications)

Chest X-Ray: Key Findings

Typically, won’t show any abnormality
Important for assessment of other causes of respiratory disease, or other causes of exacerbation and/or worsening symptoms (e.g., pneumonia | foreign body in airways)

SYNOPSIS:

While targeted questions and examination are helpful, a good overall history and physical remain important to identify co-morbidities (e.g., sinusitis, rhinitis, GERD, other respiratory disorders, obstructive sleep apnea). It is also important to remain cognizant that multiple external factors can trigger an attack, including respiratory infections, smoking, allergies, exposure to cold or humid air, pollution, exercise, severe emotional and/or physical stress. Spirometry is currently the primary diagnostic tool for asthma.

KEY POINTS:

Severity of Asthma

Asthma severity is determined by the following
- Reported symptoms over the previous two to four weeks
- Standardized questionnaires – e.g., the Asthma Control Test
  - Provides numerical score to determine if the symptoms are well controlled
Current level of lung function: PEFR | FEV₁ | FEV₁/FVC
Number of exacerbations requiring oral glucocorticoids in the previous year

Types of Asthma

Intermittent

No interference with normal activities between exacerbations
Daytime asthma symptoms: ≤2 days per week
Nocturnal awakenings: ≤2 per month
Use of short-acting beta agonists to relieve symptoms: ≤2 days per week
FEV₁ between exacerbations: Within normal range (i.e., ≥80 percent of predicted)
FEV₁/FVC ratio between exacerbations: Within normal range (based on age-adjusted values)
Oral glucocorticoids requirements: ≤1 exacerbation per year
Other circumstances
- Use of Short-Acting Beta Agonists (SABAs) to prevent exercise-induced asthmatic symptoms (even if exercising more than twice per week)
- Infrequent circumstances: Exposures such as cat encounter or URTI

Mild persistent

Minor interference with normal activities
Symptoms: >2 weekly (not daily)
Nocturnal awakenings: 3 to 4 per month (not every week)
Use of SABAs: > 2 days per week (Not daily)
FEV₁: between exacerbations: Within normal range (≥80 percent of predicted)
FEV₁/FVC ratio between exacerbations: Within normal range (based on age-adjusted values)
Oral glucocorticoids requirements: ≥2 exacerbations per year

Moderate persistent

Daily symptoms of asthma
- Some limitation in normal activity
Nocturnal awakenings: ≥1 per week
Need for SABAs: Daily
FEV₁: 60 to 80 percent predicted
FEV₁/FVC: Below normal

Severe persistent

Symptoms of asthma throughout the day
- Extreme limitation in normal activity
Nocturnal awakenings: Nightly
Need for SABAs: Several times per day
FEV₁: <60 percent of predicted
FEV₁/FVC: Below normal

When to refer to pulmonologist and/or allergist/ immunologist 

Life-threatening asthma exacerbation 
>2 bursts of oral glucocorticoids in a year 
Asthma not controlled after three to six months of active therapy and appropriate monitoring 
Unresponsive to therapy 
Diagnosis of asthma is uncertain 
Comorbid conditions that are complicating management such as
- Nasal polyposis | Chronic sinusitis | Severe rhinitis | Allergic bronchopulmonary aspergillosis (see review below in ‘Learn More – Primary Sources), COPD, vocal cord dysfunction
Additional diagnostic tests are needed such as
- Skin testing for allergies | Bronchoscopy | Complete pulmonary function tests
Potential candidate for allergen immunotherapy