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Wheezing is a symptom as well as a physical finding. Wheezing occurs as a result of airway narrowing. Asthma is the most classic cause of wheezing, but wheezing may be part of COPD, heart failure exacerbation (cardiac asthma), bronchiolitis in children, anaphylaxis, toxic inhalation, foreign body aspiration, tracheomalacia, or vocal cord dysfunction.
Evaluation
History:
Wheezing in a patient with known asthma or COPD is usually presumed to represent an exacerbation. A history of cough, postnasal drip, exposure to allergens, or toxic or irritant gases may suggest a trigger. Acute onset without a history of lung disease suggests allergic reaction or impending anaphylaxis. Worsening with cold air, dust, tobacco smoke, perfumes, or other factors suggests asthma.
Physical examination:
Localized wheezing suggests focal bronchial obstruction by tumor or foreign body. Diffuse wheezing indicates that all airways are involved or that the site of airway narrowing is in the trachea or at the level of the vocal cords. Urticaria or angioedema suggests an allergic reaction. Fever and URI symptoms suggest infection, especially bronchiolitis in children < 2 yr. Crackles, distended neck veins, and peripheral edema suggest heart failure.
Testing:
A pulse oximetry reading and a chest x-ray should be taken. Segmental or subsegmental atelectasis or infiltrate suggests an obstructing endobronchial lesion. Radio-opacity in the airways or focal areas of hyperinflation suggests a foreign body.
Spirometry (see Tests of Pulmonary Function (PFT)) can confirm airflow limitation and quantify its reversibility and severity. Flow-volume loops can help diagnose large airway obstructions, such as those caused by tumors or vocal cord dysfunction, and can differentiate extrathoracic from intrathoracic sites of obstruction. Extrathoracic variable obstruction causes flattening of the inspiratory limb of the flow-volume loop, whereas intrathoracic variable obstructions cause flattening of the expiratory limb (see Fig. 3: Tests of Pulmonary Function (PFT): Flow-volume loops. [parts E and F]). Fixed lesions affect both limbs.
Treatment
Definitive treatment of wheezing is treatment of underlying causes. Wheezing itself can be relieved with inhaled bronchodilators (eg, albuterol 2.5 mg nebulized solution or 180 μg metered dose inhalation) except in the case of foreign body or vocal cord abnormalities.
Last full review/revision November 2005
Content last modified November 2005
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