Spirometry to predict dry powder inhaler performance: Insights from in-check DIAL.

Purpose: Chronic obstructive pulmonary disease (COPD) management involves pharmacologic therapy delivered via inhalers. Choosing the right inhaler can be challenging. The In-Check Dial G16®, designed as a training device, helps clinicians assess inspiratory capacity by simulating inhaler resistance but can be time-consuming. Spirometry quantitatively assesses lung function and is essential for COPD diagnosis. This study explores spirometry as a predictive tool for assessing the inspiratory flow required for dry powder inhalers (DPI).

Methods: We included COPD patients using inhalers for at least one month who underwent spirometry in two Portuguese hospitals. On the same day, patients' inhalatory capacity was evaluated with the In-Check DIAL G16®. Patients were considered able to use the DPI if they could achieve a flow higher than 30 L/min at least three times at the R3 resistance level.

Results: Ninety-one patients enrolled, most using pressurized metered-dose inhaler/soft mist inhalers (37.4 %), low resistance (30.8 %), medium-low resistance (23.1 %), and medium resistance (8.8 %) inhalers. Peak inspiratory flow (PIF) best predicted DPI use, with a cut-off value of 3.10 L/s providing 69.2 % sensitivity and 76.9 % specificity. Forced inspiratory flow at 50% of FVC (FIF) was the second-best predictor, with a cut-off value of 2.91 L/s, 63.7 % sensitivity, and 69.2 % specificity.

Conclusion: PIF's strong correlation with inhalation capacity underlines spirometry's importance in COPD evaluations. Identified PIF and FIF cut-off values assist clinicians in selecting appropriate inhalers. Spirometry offers a more accessible and time-efficient alternative to the In-Check Dial G16®, warranting further research to validate these findings and integrate spirometry-based assessments into COPD management.