ABSTRACT
Diagnosis Asthma is characterized by episodic symptoms of airway obstruction, which is at least in part reversible; alternative explanations must be excluded. Airway inflammation with edema and remodeling, rather than simply bronchospasm, is the key. Increased airway responsiveness to stimuli is characteristic. Indicators that suggest a diagnosis of asthma include wheezing, history of recurrent cough, chest tightness or difficulty in breathing; worsening of symptoms with exercise, viral infection, exposure to animal fur or feathers, mold, pollen, house dust mites, tobacco or wood smoke, changes in weather, airborne chemicals or dusts; or worsening of symptoms at night. Physical examination is not always reliable, and may include thoracic hyperexpansion or chest deformity, hunching of shoulders or use of accessory muscles, audible wheezing or a prolonged expiratory phase, increased nasal discharge or nasal polyps, or any manifestation of an allergic skin condition. The more indicators present, the more likely the
diagnosis; however, the absence of wheezing does not equal the absence of asthma. If a diagnosis of asthma is being considered, the next step is spirometry to determine whether airflow obstruction is present, and, if so, whether it is reversible. Forced vital capacity (FVC), FEV1, and FEV1/FVC ratio are measured before and after administration of a short-acting bronchodilator. Reduced FEV1 or FEV1/FVC shows airflow limitation, and a 12% or greater improvement in FEV1 after the administration of inhaled albuterol confirms reversibility. (1)
To be certain of an asthma diagnosis, once abnormal FEV1 is found in a patient with history and physical exam findings consistent with asthma, other differential diagnoses must be excluded, such as chronic obstructive pulmonary disease, congestive heart failure, pulmonary embolus, laryngeal or vocal cord dysfunction, and mechanical airway obstruction.
