Other Diagnostic Tests

• Spirometry, an objective measure of pulmonary function, can be used to assist in confirming the diagnosis of asthma.

• Useful pulmonary function tests include the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). The following values support a diagnosis of asthma:

• Decreased FEV1/FVC relative to predicted values demonstrates airway obstruction. The ratio may be normal between exacerbations.

• 12% or greater (at least 200 mL) improvement in FEV1, after an inhaled bron-chodilator demonstrates a reversible obstruction. A 2-to 3-week course of oral corticosteroids may be necessary to demonstrate reversibility in airway obstruction.

• A decrease in FEV1, of 15% or more after an exercise test is diagnostic for exercise-induced asthma.

• Assessment of diurnal variation in peak expiratory flow (PEF) may be useful in patients who have asthma symptoms and normal spirometry.

• When spirometry is equivocal, a 20% or greater decrease in FEV1 after the administration of methacholine is diagnostic for asthma. A negative bronchoprovocation test with methacholine may help rule out asthma.

• A positive allergen test may help guide nonpharmacologic therapy but is not diagnostic for asthma.

The Prevention and Treatment of Headaches

The Prevention and Treatment of Headaches

Are Constant Headaches Making Your Life Stressful? Discover Proven Methods For Eliminating Even The Most Powerful Of Headaches, It’s Easier Than You Think… Stop Chronic Migraine Pain and Tension Headaches From Destroying Your Life… Proven steps anyone can take to overcome even the worst chronic head pain…

Get My Free Audio Book

Post a comment