In recent years, allergic diseases, particularly asthma, have been acquiring an increasing importance in the developed countries, due to the rising of its prevalence and morbidity and the economic burden associated, becoming a serious public health problem. Recent therapeutic approaches in asthma patients may help to prevent most of the crisis and remain free of symptoms. Several inhalation devices are available for drug delivery to the lungs, including metered-dose inhalers (MDIs), dry powder inhalers (PDIs) and nebulizers. Although this variety of devices used for drug delivery to the bronchial tree have shown encouraging results, a great amount of the drug does not reach the goal and remains in the mouth (less than 20% of the drug can reach the lungs) and higher airways. This causes not only a loss of drug but also increases costs and produces undesirable side effects. For better efficiency of the process, spacers, such as the Volumatic® used in the study herein reported, are used. This paper will describe and summarize part of the developments being carried out so far at the University of Minho in this domain, as well as the latest developments in order to understand the characteristics of the used spacer and the parameters affecting its performance. By using computational fluid Dynamics (CFD) techniques, the behavior of the drug flow inside the spacer, combined with a pressurized metered-dose inhaler (pMDI), the discrete phase model (DPM) flow inside the Volumatic® is also reported. The results obtained are also analyzed and discussed, using two different 3D grid types (Cooper and T-Grid). The insight provided by the detailed data of the flow patterns inside the Volumatic® provides possible options for new geometry possibilities for the spacer devices.
Copyright © 2009 by ASME
