Department of Bioengineering, Northeastern University, Boston, MA, USA.
Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.
Ann Biomed Eng. 2018 Mar;46(3):498-512. doi: 10.1007/s10439-017-1971-9. Epub 2017 Dec 20.
The airway structure continuously evolves from birth to adulthood, influencing airflow dynamics and respiratory mechanics. We currently know very little about how airflow patterns change throughout early life and its impact on airway resistance, namely because of experimental limitations. To uncover differences in respiratory dynamics between age groups, we performed subject-specific airflow simulations in an infant, child, and adult conducting airways. Airflow throughout the respiration cycle was calculated by coupling image-based models of the conducting airways to the global respiratory mechanics, where flow was driven by a pressure differential. Trachea diameter was 19, 9, and 4.5 mm for the adult (36 years, female), child (6 years, male), and infant (0.25 years, female), respectively. Mean Reynolds number within the trachea was nearly the same for each subject (1100) and Womersley number was above unity for all three subjects and largest for the adult, highlighting the significance of transient effects. In general, air speeds and airway resistances within the conducting airways were inversely correlated with age; the 3D pressure drop was highest in the infant model. These simulations provide new insight into age-dependent flow dynamics throughout the respiration cycle within subject-specific airways.
气道结构从出生到成年不断演变，影响气流动力学和呼吸力学。我们目前对生命早期气流模式如何变化及其对气道阻力的影响知之甚少，主要是因为实验的局限性。为了揭示不同年龄段之间呼吸动力学的差异，我们在婴儿、儿童和成人的气道中进行了特定于主题的气流模拟。通过将气道的基于图像的模型与全球呼吸力学耦合，来计算整个呼吸周期的气流，其中气流由压力差驱动。成人（36 岁，女性）、儿童（6 岁，男性）和婴儿（0.25 岁，女性）的气管直径分别为 19、9 和 4.5mm。每个受试者的气管内平均雷诺数几乎相同（1100），所有三个受试者的沃默斯利数均高于 1，其中成人最大，突出了瞬态效应的重要性。一般来说，在气道中，气流速度和气道阻力与年龄呈反比；婴儿模型中的 3D 压降最大。这些模拟为特定于主题的气道中整个呼吸周期内与年龄相关的流动动力学提供了新的见解。
