Mh. Tawhai et Pj. Hunter, Characterising respiratory airway gas mixing using a lumped parameter model of the pulmonary acinus, RESP PHYSL, 127(2-3), 2001, pp. 241-248
A lumped parameter model of a human pulmonary acinus is derived using resul
ts from gas mixing simulations in an anatomically-based asymmetric multi-br
anching model of the acinus coupled to a symmetric conducting airway model.
The model respiratory airways change length in proportion to the cube root
of their volume change, and the diameters are updated accordingly assuming
constant duct cross-sectional area. The lumped parameter model applies a f
lux boundary condition at the end of a transitional bronchiole during inspi
ration to enable realistic concentration changes at this position; during e
xpiration inspiratory parameters are used to predict concentrations at the
end of the associated transitional bronchiole. The predicted concentrations
are used as time-varying fixed boundary conditions at the end of the trans
itional bronchiole in conducting airway models during expiration. The curre
nt lumped parameter model is most accurate for tidal volumes between 500 an
d 1500 ml, and equal inspiration and expiration durations of 2 sec. The mod
el's accuracy decreases for changes in breath duration. (C) 2001 Elsevier S
cience BN. All rights reserved.