Deposition of micrometer particles in pulmonary airways during inhalation and breath holding

• Published in: Journal of biomechanics Vol. 45; no. 10; pp. 1809 - 1815
• Main Authors: Imai, Yohsuke, Miki, Takahito, Ishikawa, Takuji, Aoki, Takayuki, Yamaguchi, Takami
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 26.06.2012; Elsevier; Elsevier Limited
• Subjects: Adult; Aerosol; Aerosols; Airways; Biological and medical sciences; Biomechanics; Computational mechanics; Computerized, statistical medical data processing and models in biomedicine; Deposition; Drug delivery; Experiments; General pharmacology; Humans; Inertia; Inhalation; Inhalation - physiology; Lung; Lung - diagnostic imaging; Lung - physiology; Male; Medical sciences; Micrometers; Models and simulation; Models, Biological; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Physical Medicine and Rehabilitation; Studies; Subject-specific model; Terminal velocity; Tomography, X-Ray Computed - methods; Computational mechanics; Drug delivery; Subject-specific model; Aerosol; Lung; Human; Pharmaceutical technology; Radiodiagnosis; Drug carrier; Respiratory system; Modeling; Inhalation; Biomechanics; Respiratory tract; Apnea; Medical imagery; Aerosol deposition; Microparticle; Computerized axial tomography; Respiration; Biomedical engineering
• ISSN: 0021-9290; 1873-2380; 1873-2380
• DOI: 10.1016/j.jbiomech.2012.04.017

We investigated how breath holding increases the deposition of micrometer particles in pulmonary airways, compared with the deposition during inhalation period. A subject-specific airway model with up to thirteenth generation airways was constructed from multi-slice CT images. Airflow and particle transport were simulated by using GPU computing. Results indicate that breath holding effectively increases the deposition of 5μm particles for third to sixth generation (G3–G6) airways. After 10s of breath holding, the particle deposition fraction increased more than 5 times for 5μm particles. Due to a small terminal velocity, 1μm particles only showed a 50% increase in the most efficient case. On the other hand, 10μm particles showed almost complete deposition due to high inertia and high terminal velocity, leading to an increase of 2 times for G3–G6 airways. An effective breath holding time for 5μm particle deposition in G3–G6 airways was estimated to be 4–6s, for which the deposition amount reached 75% of the final deposition amount after 10s of breath holding.