Model of the pulmonary ventilation and effects of airways properties on drug delivery to the lungs

Karla Sanchez¹, Mark Allen¹, Brian Chang², Rosie Earl¹ & Kim Parker³

¹Cambridge Design Partnership, Church Road, Toft, Cambridge CB23 2RF, UK

²Cambridge Design Partnership, 801 West Morgan Street, Suite 120, Raleigh, NC 27603, USA

³Department of Bioengineering, Imperial College London, UK

Summary

A model of the lungs is presented focusing on the mechanical properties of the airways and their effect on the tracheobronchial and alveolar regions. Difficulties in breathing can result in poor particle deposition of drugs in the lungs and therefore poor patient outcome. The model explores the expected behaviour of these properties in young healthy controls vs ageing and pathological conditions e.g., Chronic Obstructive Pulmonary Disorder (COPD). The aim of the model is to provide an inexpensive tool for assessment of physiological parameters of airways and as an aid in design of devices that deliver drugs to the lungs. This is achieved using a fractal model which analyses all generations of the lung simultaneously, considering the stiffness of airways tissue and the interaction with transmural pressure to allow physical property changes to the lung to be assessed quickly. The model highlights that a decrease in lung compliance and input pressure, decreases the respiratory volume. The model also indicates airway opening size and transmural flux are sensitive to transmural pressure and the diffusivity at the alveolar region. These insights have significant implications to how we treat respiratory pathologies depending on the mechanical effects of age and disease. Future iterations of this model aim to include parameters such as air velocity, mucus viscosity and gas exchange to allow further interrogation to help understand and improve drug deposition characteristics.

Key Message

We have developed a simple, bifurcating lung network model that outputs key breathing parameters from the trachea down to the alveolar sacs. The reduced computational cost removes barriers to understanding how aging and respiratory diseases can affect drug delivery to the lungs.