Good inhaler technique is key for an effective inhalation treatment and reduction of critical inhaler errors. Recent publications show that treatment effects can be improved if inhalers are easy to use and support patients with pulmonary hypertension in their inhaler technique (Gesslet, T, Pulmonary Circulation 2017; 7(2) 505-513). The aims of this study were the usability assessment of the soft mist inhaler (PFSI, Resyca, Netherlands),evaluation of inhalation flow profiles with the resistance of the inhaler, and observation of ability to safely use the inhaler.

A formative human factors study was conducted in 15 patients with pulmonary hypertension, functional class II, III, or IV, thereof 3 patients with handling difficulties like scleroderma. User device interaction, inhaler flow profiles and use tasks were assessed for all patients. Patient satisfaction and user needs were assessed in qualitative interviews.

All patients were able to inhale with an inhalation duration of 3.6 seconds. Median inhalation duration was 6.0 seconds, median inhaled volume was 1.1 L and median flow rate was 13.5 L/min. Inhalation flow profiles for 10th and 90th percentile was 8.8 and 23.6 L/min respectively.

87% of patients rated the inhalation treatment with several breaths and performing of required use steps as comfortable. 73% assembled the device correctly with instructions for use.

Results from this human factors study show that patients comfortably inhaled slow and deep with the high resistance soft mist inhaler. The intuitive device design supported patients in applying steps to good inhalation technique.