The causes of wheezing may be recalled by following the air passages from the larynx to the alveoli.
· Larynx. Laryngitis may obstruct the inspiration of air causing wheezing.
· Trachea. This brings to mind tracheobronchitis and foreign bodies.
· Bronchi. This prompts the recall of bronchitis, bronchiolitis, and bronchial asthma. It should also remind one of pulmonary emphysema and bronchogenic carcinoma.
· Alveoli. This suggests pulmonary edema with associated cardiac asthma.
Approach to the Diagnosis
CBC, chest x-ray, sputum smear, and cultures will help to diagnose infectious causes of wheezing. Bronchial asthma can be diagnosed by sputum for eosinophils and pulmonary function testing. Cardiac asthma (due to CHF) can be diagnosed by a venous pressure and circulation time, electrocardiogram (EKG) and echocardiography. Bronchoscopy may be necessary if a foreign body is suspected.