Assessment of the Power Required for Optimal Use of Current Inhalation Devices.

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.

Inhalation device requirements for patients' inhalation maneuvers.

BACKGROUND: Inhaled drugs are the mainstay of treatment for lung diseases such as asthma and chronic obstructive pulmonary disease. However, failure to use inhalation devices correctly can lead to a poorly controlled status. A vast number of inhalation devices exist and each device has specific requirements to achieve optimum inhalation of the drug. Currently, there is no overview of inhalation requirements considering all devices. This article presents a review of the literature on different inhalation device requirements and incorporates the data into a new inhalation flow algorithm. METHODS: Data from literature on commercially available inhalation devices were evaluated and parameters, such as inhalation flow rate, flow acceleration, inhalation volume, and inspiration time assessed for the required inhalation maneuver specific to the device. All agreed upon data points were used to develop an inhalation flow algorithm. RESULTS: The literature analysis revealed availability of robust data for the required inhalation flow characteristics for most devices and thus for the development of an algorithm. For those devices for which these parameters are not published, the minimum required flow criteria were defined based on published data regarding individual aspects of aerosol quality. CONCLUSIONS: This review provides an overview of inhalation devices available on the market regarding requirements for an acceptable inhalation maneuver and shows which goals should be achieved in terms of inhalation flows. The presented algorithm can be used to develop a new computer based measurement system which could help to test and train patients' individual inhalation maneuvers with their inhalation devices.