modelling | Acta Medica Marisiensis

Evaluation of the Effect of Lung Morphometry on the Deposition of Inhaled Particles

Sárkány Z¹, Kudela G², Horváth A³, Balásházy I⁴, Hofmann W⁵, Sabău M⁶

1 University of Medicine and Pharmacy, Târgu Mureș, Romania
2 Faculty of Informatics, Eötvös Loránd University, Budapest, Hungary
3 Chiesi Hungary, Budapest, Hungary
4 Environmental Physics Laboratory, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary
5 Division of Physics and Biophysics, Department of Materials Research, University of Salzburg, Salzburg, Austria
6 Department of Physiology, University of Medicine and Pharmacy, Târgu Mureș, Romania

Introduction: The human respiratory tract is a complex, asymmetrical, tree-like system of tubular structures, optimized for the transport and distribution of respiratory gases. The objective of this study is to use a computerized lung model to study the effect of lung morphometry on the airway deposition of inhaled particles.
Material and methods: We used a stochastic lung model to simulate the total and regional deposition of 0.01–10 µm particles through oral breathing in sitting condition. The effect of lung morphometry was examined using the same model with a modified algorithm to create a fully symmetrical lung geometry.
Results: Total deposition curves show similar deposition trends for the two models, the symmetric model returning slightly lower deposition values for all particle sizes. In the bronchial region deposited fractions are highly similar, the symmetric model predicting deposition values that are 2.1–4.6% higher for particles in the 0.01–0.1 µm size range. In the acinar region deposition values are up to 27.6% lower in the case of 0.2 µm particles.
Conclusions: Our study suggests that the deposition of inhaled particles is dependent mainly on particle size, and to a smaller extent on the lung geometry the models are built on. Deposition fractions yielded by the two models are highly similar, although there is a shift in the deposition of inhaled particles from the acinar region towards the bronchial region in the symmetric model.

Background: The aim of this study was to use a computerized lung model to simulate the deposition of inhaled particles in the human airways during a severe asthma attack, in order to find the combination of breathing- and particle-related parameters which leads to the highest deposited fractions in the target areas of the airways.
Material and Method: A stochastic lung model was used to simulate the deposition of 1 nm – 100 µm particles during a severe asthma attack in bronchial generations 9-16. Breathing parameters were chosen to reflect the use of a therapeutic inhalation device, with a 10 s symmetrical breathing cycle and 2000 ml tidal volume. To maximize the deposited fraction in the target areas, further simulations were carried out changing the tidal volume (750-3000 ml), the length of the breathing cycle (2-20 s) and the length of breathing pause following inhalation (0-10 s).
Results: The highest deposited fraction of 51.50% in bronchial generations 9–16 was obtained in the case of 0.01 µm particles, this value being more than4 times higher compared to the highest deposition of 3–6 µm particles currently used in inhalation devices (11.81% in the case of 5 µm particles). Modifying breathing-related parameters did not lead to valuable increases in the deposited fractions in the investigated region.
Conclusions: Deposition fractions in the therapeutically important areas of the airways may be more than4 times higher in the case of 0.01 µm particles, compared to particles currently used in the treatment of asthma bronchiale.