Although spirometry has proven to be very useful for researching and keeping under control chronic diseases, such as asthma, this diagnostic tool is underutilized in many countries. In this article we will highlight some of the many advantages of performing spirometry tests in patients with asthma. Along this text we will answer briefly the questions why?, how? and when?
By América Torres
Why Use Spirometry to Confirm an Asthma Diagnosis?
Usually, a clinical evaluation of symptoms associated with asthma and their pattern of recurrence is enough to obtain a diagnosis. However, it is advisable to check for airway obstruction and its reversibility to confirm the initial diagnosis. For instance, an increase of more than 12% and at least 200 ml in FEV1 after inhaling a bronchodilator are telltale signs.
In an accurate spirometry test, a reduced range from FEV1 to FVC indicates airway limitation. The diagnosis of obstruction, in general, is made using the prebronchodilator ratio of FEV1 to FVC, that is, when it shows a value less than the lower Limit of Normal (LLN). As you know, the LLN is estimated by subtracting 1,645 times the standard deviation from the predicted value.
When the spirometry of a patient clinically diagnosed with asthma appears normal, it is necessary to look for another diagnoses because it is likely that the first one is incorrect. Clearly, this simple and painless test is very valuable to prevent misdiagnosis and delayed treatment.
How and When to Use Spirometry for Asthma?
Variability in airway caliber—whether spontaneous or treatment-related—is a key feature of asthma. This variation can be clearly demonstrated through spirometry, as changes in lung function over time (either improvement or deterioration) provide objective evidence.
To gain a more complete picture of a patient’s respiratory health, it is advisable to perform multiple spirometry tests over several days or weeks. This approach helps confirm or rule out an asthma diagnosis. How often should spirometry be done? There’s no universal rule—the frequency depends on the individual case and the clinical judgment of the physician. However, the 2014 report of the Global Initiative for Asthma (GINA) report offers the following general recommendations for performing spirometry in asthma patients:
- At the time of diagnosis
- At the start of treatment
- 3 to 6 months after initiating asthma control
- Periodically thereafter
An increase or decrease in FEV1 of >12% and >200 mL helps document airway caliber variability and may be useful in patients who show no acute bronchodilator response. Lung function also serves as a predictive marker for future risks. For example, a predicted FEV1 <60% is potentially an independent and modifiable risk factor for disease exacerbation. Performing regular spirometry can help detect early declines in lung function and guide timely intervention.
The Importance of Accurate Spirometry in Asthma Management
You’ve likely noticed the many benefits spirometry offers pulmonologists—and especially patients—in the detection and treatment of asthma. However, these advantages can be overshadowed when spirometry tests are not conducted properly.
The British Guideline on the Management of Asthma points out the disadvantages of obtaining inaccurate results when spirometry are not carried out with a device of good quality that was properly calibrated, and performed by an operator who lacks adequate training.
Fortunately, with SpiroScout, you can ensure precise, reliable spirometry results. This easy-to-use ultrasonic spirometer is designed for patients of all ages and features our exclusive disposable mouthpieces, ScoutTube, to prevent cross-contamination. Thanks to its advanced SharpFlow (ultrasonic) technology, SpiroScout is calibration-free, making it a hassle-free option for your practice. The intuitive LFX Software allows you to zoom in on specific parts of the respiratory curve and generate comprehensive, modern reports with clear, visual graphics. SpiroScout is truly the best choice for optimizing lung health care for your patients.
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REFERENCES
Chhabra SK. Clinical application of spirometry in asthma: Why, when and how often? Lung India. 2015 Nov-Dec;32(6):635-7. doi: 10.4103/0970-2113.168139. PMID: 26664177; PMCID: PMC4663874. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663874/
Global Strategy forAsthma Management and Prevention. GINA 2014
https://ginasthma.org/wp-content/uploads/2019/01/2014-GINA.pdf
https://pubmed.ncbi.nlm.nih.gov/25323740/
