Diagnose if detecting wheezes, rhonchi, or just a long expiratory phase (i.e. expiration longer than inspiration. Strongly suspect if there’s a history of similar episodes lasting weeks or more.
Confirm with a trial of inhaled β-2 agonist (e.g. albuterol), nebulized in the office, and/or by inhaler to take home. Look for improvement in symptoms & in Peak Flow.
May need formal PFTs to make the diagnosis (looking for a reduced FEV1 : FVC ratio, that improves >15% with nebulized β-2 agonist. Methacholine challenge test is the gold standard.
Can diagnose Exercise-Induced Asthma by β-2 agonist before exertion, or trial of a daily leukotriene antagonist like monteleukast (Singulair). Formal pulmonary function tests after a treadmill session can be done, but rarely utilized.
Main pitfall is “cardiac asthma” (CHF presenting with wheezes instead of rales).
See posting Chronic Dyspnea – 1.