Focus on Diagnosis: Spirometry

Abstract

1. Kamakshya P. Patra, MD 1. Department of Pediatrics, Mayo Clinic, Rochester, MN. * Abbreviations: FEF25%–75%: : forced expiratory flow, midexpiratory phase FEV1: : forced expiratory volume fraction in 1 second FVC: : forced vital capacity PEFR: : peak expiratory flow rate Office spirometry, traditionally done by the pulmonary specialist, has become commonplace in the pediatric primary care office. The National Asthma Education and Prevention Program guidelines recommend routine use of spirometry for the initial diagnosis and ongoing management of asthma. A nationwide survey demonstrated that only 21% of physicians used spirometry for the management of children with asthma, as per the guidelines. And, approximately one half of the physicians were unable to interpret the results of spirometry. Office spirometry has been shown to result in change in asthma management in 15% of children. In 45% of cases, the severity of asthma was underrated by the providers in the absence of spirometry. A peak flow meter, which measures peak expiratory flow rate (PEFR), is a simple, inexpensive, and portable device that may be helpful in the management of asthma. However, PEFR is effort-dependent and does not reflect small airway function. The average cost of a good spirometer is in the $1,500 to $2,000 range. There must be training of the office personnel who perform the spirometry, and the spirometer should be calibrated at least daily. In general, patients must be at least age 4 to 4.5 years to perform reliable forced vital capacity (FVC) maneuvers required for spirometry. A 7-year-old girl has experienced wheezing since age 3 years and has been diagnosed as having asthma. Her symptoms did not improve despite therapy with albuterol, corticosteroids, salmeterol, and monteleukast. She was referred to the pediatric pulmonology clinic for persistent symptomatology. Spirometry was performed, which revealed a fixed obstruction. Flow volume loops revealed truncation of inspiratory and expiratory limbs (Fig 1). Computed tomography scan of the …