Bronchial Asthma: Diagnostic Tests

Obligatory medical device diagnostics.

  • Spirometry (basic examination in the context of pulmonary function diagnostics) – belongs to the initial diagnostics/stage 1 to confirm the diagnosis as well as to monitor the course [bronchial asthma:
    • Evidence of obstruction (narrowing or obstruction of the airways): FEV1 (expiratory one-second capacity or forced expiratory volume) decreased and FEV 1 / VC < 70% (VC = vital capacity)Note: A clear and therapy-requiring obstruction can be present even with normal lung function values [guidelines: S3 guideline]. With appropriate clinical symptoms and normal spirometry is therefore basically a bronchial hyperreactivity testing (testing of the excessive responsiveness of the airways to an exogenous stimulus (eg, on the treadmill; see also methacholine test) to perform.
    • Evidence of reversibility: (approximate) normalization after bronchospasmolysis/medication relaxation of the contracted, i.e., “cramped” bronchial musculature; bronchial asthma is indicated by a normalization of FEV1 in the bronchospasmolysis test (administration of a bronchodilator medication) or an additional intake of more than 400 ml.COPD is classified according to GOLD (Global Initiative for Chronic Obstructive Lung Disease) on the basis of FEV1: see below COPD / medical device diagnostics]
  • Reversibility test using bronchospasmolysis (drug-induced relaxation of contracted, i.e., “cramped” bronchial muscles) – allows differentiation between bronchial asthma and COPD First, a peak flow measurement is performed. If the value is decreased, a bronchodilator (bronchodilator) spray (beta-2-sympathomimetic: e.g. – 400 μg salbutamol) is administered. This tests whether the airways can be widened by this measure. If this is the case, the peak flow value also improves significantly and bronchial asthma is most likely present. If the previously lowered peak flow value remains lowered even after the attempt to expand the airway, this speaks more for a chronic obstructive pulmonary disease (COPD).
  • Peak flow measurement (airflow, more precisely the respiratory flow rate, during a forced strong expiration (exhalation)) – important tool for distinguishing asthma disease from chronic obstructive pulmonary disease (COPD), as well as for monitoring the progression of bronchial asthma. Circadian variability of peak flow is characteristic of bronchial asthma. In the early morning hours, the peak flow value is lower than during the day, i.e. the airway obstruction is more pronounced.
  • FeNO measurement (synonyms: Determination of nitric oxide concentration (FENO) in exhaled air; multiple breath test method, FENO test) – Biomarker of inflammation/diagnostic method for determination of FeNO (nitric oxide) level in exhaled air for detection of present inflammatory processes and chronic pulmonary diseases:
    • Bronchial asthma: > 50 ppb (high value), in nonsmokers supports the diagnosis of eosinophilic airway inflammation (airway inflammation).
    • COPD: usually normal; decreased in former smokers.
  • Bodyplethysmography (whole-body plethysmography; large lung function) – initial diagnosis/stage 2; provides information about the degree of pulmonary hyperinflation (emphysema) and the extent of airway obstruction:
    • Bronchial asthma: residual volume (RV; amount of air remaining in the lungs after maximal expiration) unremarkable.
    • COPD
      • COPD severity 1-2(-3): RV unremarkable or slightly elevated.
      • COPD severity grade 4 (with emphysema): RV markedly elevated.
    • Interstitial lung disease: total lung capacity (TLC) decreased.
  • X-ray of the chest (X-ray thorax/chest), in two planes; belongs to the initial diagnosis as well as useful in atypical courses:
    • Bronchial asthma: unremarkable
    • COPD
      • COPD severity 1-2(-3): unremarkable
      • COPD severity grade 4 (with emphysema): diaphragmatic depression, pulmonary vascular drawing decreased.
    • Interstitial lung disease: interstitial and/or fine-spotted drawing proliferation.

Optional medical device diagnostics – depending on the results of the history, physical examination and mandatory laboratory parameters – for differential diagnostic clarification.

  • Measurement of diffusion capacity for carbon monoxide (DLCO) using the inhalation draw method; to characterize intrapulmonary gas exchange – to differentiate bronchial asthma from COPD [usually not pathologically altered in patients with asthma].
  • Computed tomography (CT) with angiography of the pulmonary arteries (CTPA) – as a basic diagnostic tool in suspected pulmonary embolism [gold standard]Alternative: pulmonary scintigraphy: V/P scintigraphy (ventilation/perfusion scintigraphy) (sensitivity (percentage of diseased patients in whom the disease is detected by using the test, i.e., a positive test result occurs): Approximately 78%; Specificity (probability that actually healthy individuals who do not have the disease in question are also detected as healthy by the procedure): 98 %)