Wheezing is a common presenting concern in the primary care setting, but its etiology can be elusive. Wheezing is associated with many disease processes, but most commonly, asthma and chronic obstructive pulmonary disease. Initial tests for wheezing typically include a chest x-ray and pulmonary function testing with bronchodilator challenge. Advanced imaging to evaluate for malignancy should be considered in patients older than 40 years with a significant history of tobacco use and new-onset wheezing. A trial of short-acting beta agonists can be considered while awaiting formal evaluation. Because wheezing is associated with reduced quality of life and increased health care costs, it is essential to develop a standardized evaluation of this common concern and expeditiously manage symptoms.

Case 2. AP is a 42-year-old patient who comes to your office because of intermittent wheezing for the past 3 months. Symptoms began after an episode of viral bronchitis. She has not had any other residual symptoms. AP had asthma as a child, but it resolved during early adolescence. She is otherwise healthy, takes no drugs, does not smoke, and exercises regularly. The results of an office spirometry show a forced expiratory volume in the first second of expiration/forced vital capacity (FEV₁/FVC) ratio of 0.67. The FEV₁ is 75% of the predicted normal value, and the FVC is normal. AP wonders if her asthma has returned.

Definition and Pathophysiology

Wheezes are high-pitched, continuous sounds that indicate lower airway obstruction.⁴³ They are caused by the beating of the walls of the airways and fluid against each other⁴⁴ and are heard in many respiratory diseases that cause obstruction or narrowing of the airway.⁴⁴

The presence of wheezing should prompt pulmonary function testing regardless of its intensity, duration, or pitch, as those features correlate only to the severity of airway obstruction, not the cause of the obstruction.^44,45 Of these characteristics, the duration of wheezing and less so the pitch are most associated with obstruction severity.⁴⁶

Wheezing can be further characterized by the portion of the respiratory cycle affected. Isolated expiratory wheezing is suggestive of milder obstruction,⁴⁷ whereas the presence of inspiratory and expiratory wheezing is more indicative of a severe narrowing of the airways. Silence, no wheezing, or severely reduced lung sounds does not equate to absence of pathology; these findings can be seen in cases of severe airway obstruction where there is almost no airflow.⁴⁶