Researchers at the Al-Azhar University in Cairo, Egypt recently reported that in the assessment of lung function in asthma patients, forced oscillometry is better than the standard spirometry test. The study was recently published in the journal Annals of Allergy, Asthma and Immunology and is entitled “Forced oscillometry bested spirometry in detecting airway function in asthma patients.”

Asthma is a common chronic inflammatory lung disease estimated to affect 27 million individuals in the United States. It is characterized by shortness of breath, cough, chest tightness and wheezing. Spirometry is the most common test to assess lung function and is often employed in asthma diagnosis and disease monitoring. This method has, however, some limitations including reproducibility issues and the fact that it relies on patient cooperation and effort.

Forced oscillometry is a non-invasive method that has been developed as a patient-friendly test to measure respiratory mechanics. The device requires a passive cooperation of the patient by breathing normally through the mouth.

In this study, forced oscillometry (resistance at 5, 20, and 5–20 Hz) was compared to spirometry for the detection of the site of airway obstruction in 50 asthma patients and 50 matched healthy controls.

Researchers found that spirometry allowed the detection of airway obstruction in all asthma patients, and that 8% of the patients had isolated small airway obstruction, 10% large airway obstruction, and 82% a small and large airway obstruction. On the other hand, forced oscillometry detected that 12% of the patients had normal airway resistance, 50% had isolated small airway obstruction with frequency-dependent resistance, and 38% small and large airway obstruction with frequency-independent resistance. There was a statistically significant difference between both methods for the detection of the airway obstruction site.

The team concluded that forced oscillometry can assess normal airway function better than spirometry in asthma patients. Forced oscillometry also allowed a better detection of isolated small airway obstruction in patients with bronchial asthma in comparison to spirometry.

“Forced oscillometry provides a rapid, noninvasive measurement of airway resistance, and can be used easily in the diagnosis and management of airway diseases,” concluded the research team according to a news release. “Future work is required to assess the role of this specific and effective test in the diagnosis and monitoring of different respiratory diseases.”