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Forced oscillometry bested spirometry in detecting airway function in asthma patients

Compared with spirometry, forced oscillometry better detected normal airway function in patients with asthma and better detected isolated small airway obstruction in patients with bronchial asthma, according to study results.   

Although spirometry is common in assessing airway function in bronchial asthma, this method has limitations, according to Manal Refaat Hafez, MD, of the chest department at Al-Azhar University in Cairo, Egypt, and colleagues. They therefore sought to assess spirometry vs. forced oscillometry — a patient-friendly test requiring passive cooperation of the patient breathing normally through the mouth — for the detection of the site of airway obstruction in 50 patients with known stable asthma and 50 age- and gender-matched healthy controls. All study participants underwent spirometry and forced oscillometry.

According to study results, significant differences were observed between the two techniques for the detection of airway obstruction site (P = .012).

All patients with asthma tested positive for airway obstruction by spirometry, of which 82% had large and small airway obstruction. This was followed by 10% with isolated large airway obstruction only and 8% with isolated small airway obstruction only. With forced oscillometry, 50% of patients had isolated small airway obstruction with frequency-dependent resistance, 38% had large and small airway obstruction with frequency independent resistance and 12% had normal airway resistance.

The researchers observed a negative correlation between forced oscillometry indices and spirometric indices (P < .01).

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

Disclosure: The researchers report no relevant financial disclosures.