particles | Acta Medica Marisiensis

Introduction: The objective of this study was to investigate with the help of a computerized simulation model whether the treatment of an acute asthma attack can be individualized based on the severity of the attack and the characteristics of the patient.
Material and Method: A stochastic lung model was used to simulate the deposition of 1 nm – 10 µm particles during a mild and a moderate asthma attack. Breathing parameters were varied to maximize deposition, and simulation results were compared with those obtained in the case of a severe asthma attack. In order to investigate the effect of height on the deposition of inhaled particles, another series of simulations was carried out with identical breathing parameters, comparing patient heights of 155 cm, 175 cm and 195 cm.
Results: The optimization process yielded an increase in the maximum deposition values of around 6–7% for each type of investigated asthma attack, and the difference between attacks of different degree of severity was around 5% for both the initial and the optimized values, a higher degree of obstruction increasing the amount of deposited particles.
Conclusions: Our results suggest that the individualization of asthma attack treatment cannot be based on particles of different size, as the highest deposited fraction in all three types of attacks can be obtained using 0.01 µm particles. The use of a specific set of breathing parameters yields a difference between a mild and a moderate, as well as a moderate and a severe asthma attack of around 5%.

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.