dc.description.abstract |
A Hydraulic Lung has been designed and constructed. The Hydraulic Lung can inhale
through a Dry Powder Inhaler (DPI) with a pre-determined level of inspiratory effort,
and the characteristics of the inhalation profile generated, such as the peak pressure
drop, peak flow rate and the flow acceleration are determined by the resistivity of the
inhaler. The Hydraulic Lung has been used to explore the relationship between the
level of inspiratory effort, the DPI resistivity and the resultant profile characteristics.
A simple empirical equation has been found to describe the peak pressure drop
achieved for any given level of inspiratory effort and device resistivity. This equation
can be adapted to provide the equivalent peak inspiratory flow rate. A second simple
empirical equation was found to describe the flow acceleration rate achieved under
defined conditions of inspiratory effort and device resistivity. A clinical study has
been performed to generate equivalent human inhalation data. A comparison between
the relationships derived from the Hydraulic Lung data and the human inhalation data
has demonstrated the validity of the key equation for pressure drop as a tool for
predicHng human inhalation characteristics. The equation for flow acceleration rate
was found to underestimate the flow accelerations achieved by human volunteers, but
with slight modification could be used for this purpose.
Correlations were established between the findings from this study and the work of
earlier researchers in this area, which was based on clinical data alone.
The Hydraulic Lung was also used as a practical tool for the evaluation of DPI
performance in-vitro, including the behaviour of devices with variable resistivity
which cannot easily be assessed using either standard pumps or sophisticated
apparatus such as the Electronic Lung. |
en_UK |