The usefulness of inspiratory flow rate during inhalation corticosteroid therapy in asthma.

Background: The recently released handheld In-Check device can be used to measure the peak inspiratory flow rate (PIF) of patients and is reportedly useful in determining whether the PIF is sufficient for using inhaler devices. In this study, we evaluated the effects of instructions for the use of the device and of the device type based on measurements of the PIF in asthma.

Objectives: One hundred and thirty-five asthmatic patients who used a fluticasone propionate Diskus (FP-DK) or a budesonide Turbuhaler (BUD-TH) were studied.

Methods: The PIF was measured by the In-Check device. For patients without a sufficient PIF of 50 l/min, instructions for the use of the device were given, and the device was changed to hydrofluoroalkan-beclomethasone dipropionate (HFA-BDP).

Results: A significant correlation between the PIF and peak expiratory flow rate (p < 0.0001) was found. In 10 patients in whom the PIF did not increase to >50 l/min after instructions, the device was changed to HFA-BDP, which resulted in significant improvements in lung function in terms of the forced expiratory volume in 1 s (p = 0.018), peak expiratory flow (p = 0.038) and the maximum expiratory flow rates at 50% (p = 0.018) and 25% (p = 0.011).

Conclusions: Measurement of the PIF by the In-Check device is useful in the clinical management of asthma, to provide an appropriate device so as to improve lung function.