Assessment of peak inspiratory flow in patients with chronic obstructive pulmonary disease

Introduction: Patients with chronic obstructive pulmonary disease (COPD) use dry powder inhalers (DPIs) for disease management. DPI effectiveness relies on the patient’s peak inspiratory flow (PIF), which may not always be optimal. We conducted an observational multicentre, prospective, real-life cohort study to determine the prevalence of suboptimal PIF in patients with COPD. Methods: 415 participants (11%, n=47 women, mean age=70±8.7 years, mean forced expiratory volume in 1 s (predicted %)=48.1%) recruited from 17 international centres had baseline PIF recorded with an In-Check Dial device at three resistance levels: (1) low, (2) high and (3) the participant’s maintenance device. We also recorded PIF from participants as they would do at home to verify their proper inhalation technique. Participants underwent spirometry and completed questionnaires (COPD Assessment Test (CAT), Test of Adherence to Inhalers (TAI)-12). Results: Of the 415 participants, 18% of DPI users (n=75) exhibited suboptimal values of PIF (as typical PIF <than what was required for tested inhalers in the study) when evaluated across DPI resistance groups ranging from low (R1) to high (R5) resistance, compared with 14% of participants (n=60) using devices without resistance (R0). Additionally, 14% of study participants were incapable of producing an optimal PIF or unwilling to do so (27%), impacting medication effectiveness. Participants with suboptimal PIF values had higher mean total CAT score (17.7±7) compared with those with optimal PIF values (12.1±7.6). When assessed globally, 37% (n=56) of participants with suboptimal PIF values did not adhere to treatment, highlighting the need for improved patient education and support. Conclusion: Suboptimal PIF is common in COPD, requiring regular assessment and tailored inhalers.