Dry powder inhaler (DPI) resistance: human behaviour and psychology of patient inspiratory effort

Abstract

Background: DPI airflow resistance (Af-Rs) may influence how respiratory patients perceive inhaler performance. Yet, limited data exists on how patients perceive the process of active inhalation (‘inhale-ability’) and whether their perception of Af-Rs affects their attitudes towards a certain DPI.

Aim: Explore the psychological and physiological aspects of patients’ inspiratory effort through DPIs with different Af-Rs to develop an ‘inhale-ability’ questionnaire for evaluating the patients’ perception to Af-Rs.

Method: Patients (COPD, asthma) of different disease severities participated in focus groups and semi-structured cognitive audio-recorded interviews that were transcribed to allow for coding of data and thematic analysis to cluster the emerging themes.

Results: COPD (n=26; age=67.2yr [SD=7.1]; FEV1=1.6L [SD=0.65]; education=National Qualifications Framework (NQF) level 2 [range=0-6]) and asthma patients (n=26; age=54.2yr [SD=14.5]; FEV1=2.5L [SD=0.85]; education=NQF level 6 [range=1-8]) associated inspiratory effort with 3 key themes: 1-Routine, 2-Confidence, 3-Control. The DPI administration routine appeared to be the greatest influence in 85%, regardless of the perceived difficulty of a DPI’s Af-Rs. Although all 52 patients acknowledged the role of confidence, this was the second most important factor (80%). Surprisingly, only 58% felt they could control their inspiratory effort for a given DPI.

Conclusion: Our results suggest that perception of inspiratory effort is variable across asthma and COPD patients and may be influenced by interpretation of the observed 3 themes. Studies need to evaluate how these themes can gauge patient perception to Af-Rs. Funded by U.S. FDA.