Background: Inhalation of medications is the cornerstone in the treatment of patients with lung diseases. A variety of inhalation devices exists and each device has specific requirements to achieve optimum inhalation of the drug. The goal of this study was to establish a clear overview on performance requirements of standard inhalation devices that should be met by the patient's breathing power and to develop a new method to measure the individual performance data. Materials and Methods: An optimum and still acceptable required breathing power (P in watts) was calculated for each device with the aid of individual device flow rates (determined by a literature search) and the flow resistances (by measuring the pressure drop over the different inhalation devices). For the in vivo part of the study, peak inspiratory flow and peak inspiratory pressure drop were measured in 21 adult patients with asthma or chronic obstructive pulmonary disease and healthy volunteers and the peak inspiratory power (PIPO in watts) was calculated. Results: Nearly no power is needed to achieve optimum results when using pressurized metered dose inhalers. For dry powder inhalers, the required power depends on the specific inhalation device. Conclusions: Inhalation devices impose differing demands on the inspiratory breathing power of patients. To ensure adequate use of the different devices, a cheap and simple assessment of patients' PIPO may be one option.
Keywords: COPD; asthma; flow rate; flow resistance; inhalation device; inspiratory breathing power.