The diagnosis of asthma involves identifying recurrent symptoms and at least partially reversible airflow obstruction while ruling out alternatives. Methodology includes a medical history, physical exam, spirometry and other studies. The exam may show signs of asthma, including difficulty breathing, wheezing, coughing, increased mucus, swelling, and possibly signs of eczema.17 Spirometry measures the patient’s forcibly exhaled breath to determine pulmonary function.18 The forced vital capacity (FVC) is a measure of forcibly exhaled air following a maximal inhalation. The forced expiratory volume in 1 second (FEV1) is a measure of the volume of air exhaled in the first second of the FVC. The presence of reversibility is determined by comparing the first spirometry with a second one following inhalation of a short-acting bronchodilator. Reversibility is defined as an improvement in the second FEV1 by 12% or more (approximately 200 ml) as compared to the unmedicated first test. Additional tests could involve the home use of peak flow meters that measure peak expiratory flow (PEF), to determine lung function trends.19
The National Institutes of Health (NIH) guidelines details four asthma levels of severity determined by day and nighttime symptoms, use of SABAs (short-acting beta2-agonists) for symptom control, interference in daily activities, lung function measured as percent of predicted value of FEV1 or PEF, PEF variability, exacerbations and other features. Diagnosis depends upon the results of medical histories and tests.
For example, using the chart on Figure 1, a patient with a history of daily symptoms, nighttime awakenings often twice a week, daily use of SABAs as needed for these symptoms and some limitation of normal activity may be classified as having moderate persistent asthma. Step 3 or 4 management may be appropriate for this patient. Whereas a patient with symptoms throughout the day, nighttime awakenings every week or two, daily use of SABAs and some limitation of normal activity may be classified as having severe persistent asthma, because asthma is assigned to the most severe category of any one finding. For this patient step 5 or step 6 treatment may be required to maintain control.20 The clinical relevance of this information is to guide the clinician in patient questioning during the review of health history.
For example, the following stepwise approach for managing asthma in youths ≥ 12 years of age and older, and in adults, provides a framework of treatment alternatives. The preferred treatment for intermittent asthma is SABA as needed. The preferred treatment choices in the previous examples can be initiated as follows:
Frequent reevaluations are critical and medication levels can be stepped up when more control is needed, and stepped down when possible and when asthma is well controlled for at least three months.
Other factors considered include level of control achieved, patient education, patient compliance, environmental factors and comorbidities. Asthma specialists should be consulted for patients with moderate or severe persistent asthma.21