James W. Stout, MD, MPH, FAAP

Introduction

•Spirometry is an office test used to assess lung function—specifically, the flow and volume of a patient’s full and forceful inhaled and exhaled breath, compared to normal tidal breathing.

•In primary care, the focus is typically on the exhaled breath to be able to diagnose and manage obstructive lung diseases, rather than more sophisticated testing, such as lung volume measures and carbon monoxide diffusing capacity.

•In pediatrics, spirometry is used most commonly for the diagnosis and ongoing management of asthma.

—However, spirometry does not provide information about the remaining (residual) volume of air in the lungs—in other words, a reduced total lung volume—which is required for diagnosing restrictive lung diseases.

—A plethysmograph, also known as a full-body box, is required to measure this residual volume to determine total lung capacity and should be used in a pulmonary function testing laboratory, with supervision of testing and interpretation of findings performed by a specialist.

Spirometry in the Management of Asthma: The Clinical Case

Spirometry permits an objective measurement of the degree of airway obstruction (impairment and risk). This is important because

•Patients’ perceptions of obstruction are notoriously inaccurate.

•Clinically significant obstruction can be present even when the chest appears to be clear at physical examination.

•Clinical symptoms alone will lead to underestimation of asthma severity approximately 30% of the time in primary care.

•Peak flow testing alone is highly variable, is not a very sensitive measure of obstruction, and is no longer recommended for diagnosis. However, it may have a role in monitoring.

•Use of spirometry enables accurate diagnosis and management of asthma.

•Roughly half of U.S. primary care offices report using spirometry for pediatric patients with asthma, representing a significant gap in usage.

•Spirometry should not be performed during an asthma exacerbation but rather when patients are in their usual state of health.

•Spirometry is easy to perform poorly, but with training and feedback, it is not hard to do well.

•Spirometry is a potent tool for improving planned asthma care, thus reducing morbidity and lowering hospitalization rates and reducing emergency department visits.

•Spirometry has several indications in primary care pediatrics. These include

—Diagnosis and severity assessment of asthma in patients ≥5 years of age

—Follow-up of asthma control (especially when changing medications)

—Evaluation of chronic cough

—Evaluation of shortness of breath and other chronic respiratory complaints

—Evaluation of baseline lung function in a patient with exercise-induced bronchospasm

•Routine use of good-quality office spirometry can improve provider and patient satisfaction with care and should also lead to better health outcomes.

•Spirometry is a reimbursable procedure. The Current Procedural Terminology^® codes are as follows:

—94010 for simple office spirometry

—94060 for pre- or postbronchodilator spirometry