Physics

Internal medicine

Dry-powder inhaler

Inhaler

Mechanics

Airflow

Psychoanalysis

Pressure drop

Engineering

Psychology

Volumetric flow rate

Asthma

Tidal volume

Peak inspiratory pressure

Peak flow meter

Confusion

Anesthesia

Respiratory system

Medicine

Mechanical engineering

Journal of Aerosol Medicine and Pulmonary Drug Delivery

Dry powder inhalers (DPIs) all have the ability to aerosolize dry powders, but they each offer different operating mechanisms and resistances to inhaled airflow. This variety has resulted in both clinician and patient confusion concerning DPI performance, use, and effectiveness. Particularly, there is a growing misconception that a single peak inspiratory flow rate (PIFR) can determine a patient's ability to use a DPI effectively, regardless of its design or airflow resistance. For this review article, we have sifted through the relevant literature concerning DPIs, inspiratory pressures, and inspiratory flow rates to provide a comprehensive and concise discussion and recommendations for DPI use. We ultimately clarify that the controlling parameter for DPI performance is not the PIFR but the negative pressure generated by the patient's inspiratory effort. A pressure drop ∼≥1 kPa (∼10 cm H

The Confusing World of Dry Powder Inhalers: It Is All About Inspiratory Pressures, Not Inspiratory Flow Rates