To provide children with asthma the best care, pediatricians and other healthcare providers who have them as their patients need to become educated on and facile in using a tool that is critical to the accurate diagnosis of asthma and asthma control. That tool is spirometry.
As one of the most common chronic diseases in childhood, asthma affects millions of children in the United States.1 Data from the 2012 National Health Interview Survey show that 6.8 million children aged younger than 18 years (9% of all children) have asthma and 10 million (14%) have been diagnosed at one time with asthma.2
Broken down by race and socioeconomic conditions, the numbers get worse. Among non-Hispanic black children, 16% have asthma and 22% have ever been diagnosed with it. Among children in poor families, 13% have asthma and 19% have received a diagnosis at one time. The worst rates are for children in fair to poor health, with 37% of children with asthma and 40% receiving a diagnosis at one time.2
These numbers highlight the many children with asthma who require ongoing management so that they can achieve and maintain good asthma control. To provide these children with the best care, pediatricians and other healthcare providers who have them as their patients need to become educated on and facile in using a tool that is critical to the accurate diagnosis of asthma and asthma control. That tool is spirometry.
“The goal of caring for children with asthma is to ensure their disease is well controlled, and that boils down to both controlling their symptoms and objectively measuring lung function with spirometry,” said John Kelso, MD, from the Division of Allergy, Asthma and Immunology, Scripps Clinic, San Diego, California.
For the past 10 years, Kelso, who also is a clinical professor of pediatrics at the University of California, San Diego School of Medicine, has conducted a workshop on spirometry at the American Academy of Pediatrics (AAP) annual meeting. The workshop provides information on the latest guidelines for the recommended use of spirometry to diagnose and monitor asthma in children, as well as instructions on how to use and interpret the findings of spirometry and incorporate this tool into office flow.
This article summarizes the workshop Kelso gave at the most recent AAP annual meeting in October 2015 in Washington, DC, with an eye to providing pediatricians with a quick primer on spirometry and some useful and accessible information to guide them when using it in the clinic. The information provided debunks several myths about spirometry that may interfere with its more widespread use. Among these myths are that spirometry can’t be used in children; spirometry takes a long time to administer and can only be performed by respiratory therapists; and the curves and numbers generated from spirometry are difficult to interpret.
Referring to the most recent national guidelines for the diagnosis and management of asthma by the National Heart, Lung, and Blood Institute, National Asthma Education and Prevention Program Expert Panel Report 3 (EPR3), Kelso highlighted the recommendation for including spirometry in a comprehensive evaluation of asthma that also includes physical examination and a detailed medical history.1 Table 1 lists these 3 main components of a thorough clinical evaluation of a child with suspected asthma.
Spirometry is specifically needed to provide an objective measure of pulmonary function, because subjective measures such as patient perceptions of airflow obstructions, medical history, and physical examination are not reliable for assessing lung status or adequate to rule out other potential conditions (Table 2).1 According to the guidelines, diagnosing asthma in the clinician’s office with spirometry is recommended over measuring peak flow meters because of the wide variability in peak flow meters and reference values.1
Once a child is diagnosed with asthma, the guidelines also recommend the use of spirometry to measure pulmonary function at 1-month to 6-month intervals, as well as ongoing monitoring over the patient’s lifetime to detect the potential for and rate of decline of pulmonary function over time. Such lifetime monitoring is needed to determine if the goals of treatment are being met or if and when adjustments are needed.1
Ongoing spirometry, along with symptom assessment, for evaluating asthma control is needed, said Kelso. This is because of the discrepancy that often occurs between what symptoms suggest and what information obtained from spirometry reveals.
“For example, a child may rarely need to use albuterol, which may suggest that his or her asthma is well controlled,” he said. “However, [his/her] spirometry may be abnormal and in that case it is important to intensify treatment because the abnormal spirometry may indicate underlying inflammation that if not adequately treated may lead to airway remodeling.”
The reverse is also true. “If a child has a normal spirometry but [he or she needs] to take albuterol frequently, that child needs to have [his/her] treatment intensified as well,” Kelso added.
Spirometry is a pulmonary function test that measures the airflow and volume during forced expiration into a spirometer. To use it, the child inhales completely to total lung capacity (TLC), seals his or her mouth over a mouthpiece, and then forcefully exhales the air and continues to blow until no more air can be expelled (residual volume). The volume of air expelled in this maneuver is the forced vital capacity (FVC).
To obtain accurate assessment of pulmonary function, correct use of the spirometer is essential. Table 3 lists criteria for assessing whether the child is performing the test well enough (ie, expending maximal effort) to provide accurate results. Of critical importance is for the child to exert maximal effort in blowing into the spirometer. If the child exhales too weakly, quits too soon, or the efforts are not reproducible, the results will not be accurate.
Although technically blowing out for 6 seconds or more is required to ensure all air is exhaled, Kelso explained that a shorter effort of 6 seconds or less is acceptable in children. To ensure an adequate result, the child must do at least 2 to 3 maximal efforts that are reproducible and provide results (flow-volume curves) that are superimposable.
Once the criteria are met, meaning that the child has exerted maximal effort in blowing into the spirometer at least 2 times with reproducible results, the results of the spirometer will reveal if the test is normal or abnormal. If abnormal, the test will show what the patterns of abnormality are; that is, whether or not these indicate obstructive lung disease or restrictive lung disease (Table 4).
For children with indications of asthma, which is obstructive lung disease, Kelso said he typically gives the child albuterol, waits 10 minutes, and then repeats the spirometry. This is to see if there is an increase in the spirometry and how much of the asthma is acutely reversible with the bronchodilator.
Clinics that care for children with asthma should have spirometry available because it improves their care, emphasized Kelso. He cited several features that are particularly useful, which are listed in Table 5.
Although he said there is some upfront cost in obtaining the machine and a learning curve in using it, the advantages of having a spirometer far outweigh either of these potential downsides. Included in the cost are the machine (~$2000.00), 3-liter calibration syringe (~$300.00), filters (~$2.00 each), and a dedicated computer/printer. He emphasized, however, that these upfront costs are quickly recouped by the reimbursement for the test.
In terms of a learning curve, he emphasized that with some experience the test is easy to interpret for both assessing if the child is using it to maximal effort and whether the results are normal or abnormal. He also emphasized that spirometry can be incorporated in the clinical setting or office flow to be done easily and quickly. His tips on how to do this are listed in Table 6.
Good asthma control in children starts with an accurate diagnosis, and an accurate diagnosis includes spirometry. Ongoing monitoring of asthma control also requires spirometry. To provide the best care for children with asthma, clinics should invest in a spirometer to give the most accurate information on which to base diagnostic and treatment decisions. The tool is easy to use and cost effective, and can be incorporated into the clinic setting to facilitate quick application to the management plan.
1. National Institutes of Health. National Heart, Lung, and Blood Institute. Expert Panel Report 3 (EPR-3): Guidelines for the Diagnosis and Management of Asthma-Full Report 2007. Available at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf.
Accessed February 17, 2016.
2. Bloom B, Jones LI, Freeman G. Summary health statistics for U.S. children: National Health Interview Survey, 2012. National Center for Health Statistics. Vital Health Stat 10. 2013:(258):1-81. Available at: http://www.cdc.gov/nchs/data/series/sr_10/sr10_258.pdf. Accessed February 17, 2016.
Ms Nierengarten, a medical writer in Minneapolis, Minnesota, has over 25 years of medical writing experience, authoring articles for a number of online and print publications, including various Lancet supplements, and Medscape. She has nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.