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DEVELOPMENT OF THE SMALL AIRWAYS AND ALVEOLI FROM DHILDHOOD TO ADULT
Citation:
Zeman, K. L. AND W. D. Bennett. DEVELOPMENT OF THE SMALL AIRWAYS AND ALVEOLI FROM DHILDHOOD TO ADULT. Presented at FASEB meeting, Washington, DC, April 7-21, 2004.
Description:
Understanding the human development of pulmonary airspaces is important for calculating the dose from exposure to inhaled materials as a function of age. We have measured, in vivo, the airspace caliber of the small airways and alveoli by aerosol-derived airway morphometry (ADAM) in children of ages 6 to 18 years and adults age 18 to 40 years. ADAM utilizes the gravitational settling time of inhaled inert particles to infer the vertical distance necessary to produce the observed loss of particles to the airway surfaces at sequential depths into the lung. Previously, we identified anatomical features of the lung, EADtrans and EADmin, associated with the caliber of the transitional, respiratory bronchioles and the alveoli, respectively. In the current study we found that EADtrans increased with age, 504?127, 558?207, and 595?175 mm, for age <14, 14-18, and >18 years, respectively, but not with respect to TLC. The conducting airway volume relative to TLC did not change, 6.7?1.4%. EADmin also increased with age, 194?25, 201?18 and 250?37 mm, respectively, generally accounting for the increase in TLC observed with age. The data indicate that from childhood to adult, a constant number of respiratory units is maintained while both the smallest bronchioles and alveoli expand in size to produce the increased lung volume with age. Funded by USEPA Cooperative Agreement CR829522 and does not necessarily reflect EPA policy.