In uncontrolled asthma, baseline measures of small airway function by forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) can predict improved control when treatment is up-titrated with high-dose combination therapies, according to study results published in Respirology.

Abnormal peripheral airway (<2 mm diameter) function is associated with asthma symptoms, recurrent exacerbations, and disease severity; therefore, targeting and monitoring peripheral airway function is likely to be a clinically useful strategy for asthma management. However, little is known about how indices that potentially reflect peripheral airway function (eg, FOT and MBNW) change with treatment and whether they can predict the treatment response.

Researchers examined whether these indices related to symptom improvement in 19 patients with uncontrolled asthma after stepping up to a high-dose inhaled corticosteroid/long-acting β2-agoinist treatment. The patients underwent spirometry, plethysmography, fractional exhaled nitric oxide, forced oscillatory resistance (Rrs5Hz) and reactance (Xrs5Hz), and indices of MBNW ventilation heterogeneity (lung clearance index, diffusion-convection-dependent [Sacin], and convection-dependent [Scond]) before and after 8 weeks of treatment with fluticasone/formoterol combination inhaler 250/10 μg, 2 puffs twice daily. They found that Rrs5Hz and Xrs5Hz related to asthma control scores and that higher Rrs5Hz and Scond predicted the magnitude of improvements in asthma control.

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The investigators concluded, “Step-up to high-dose combination treatment in uncontrolled asthma is associated with improved peripheral airway function as measured by Xrs5Hz and MBNW.” They added that, “These findings support the possible clinical usefulness of these measurements in asthma assessment, management and monitoring, and suggest the need for prospective studies in order to assess their utility in guiding clinical management of patients with asthma.”

Disclosure: This clinical trial was supported by MundiPharma International. Please see the original reference for a full list of authors’ disclosures.


Tang FSM, Rutting S, Farrow CE, et al. Ventilation heterogeneity and oscillometry predict asthma control improvement following step-up inhaled therapy in uncontrolled asthma [published online February 5, 2020]. Respirology. doi:10.1111/resp.13772