Journal of Applied Physiology, Vol 44, Issue 1 63-68, Copyright © 1978 by American Physiological Society
Collateral flow resistance and time constants in dog and horse lungs
N. E. Robinson and P. R. Sorenson
We studied collateral flow resistance in exsanguinated, excised lower lobes
and accessory lobes of dog and horse lungs, respectively. A double lumen
catheter obstructed a peripheral airway isolating a segment of the lobe.
Oxygen flowed into the segment via a rotameter which measured flow (Vcoll)
while the inner catheter recorded segment pressure (Ps). Gas delivered into
the segment flowed out via collateral channels. Collateral flow resistance
was calculated as (Ps - PL)/Vcoll, where PL = static transpulmonary
pressure. Rcoll at PL = 20, 10, and 5 cm H2O averaged 0.24, 1.25, and 2.65
cmH2O.ml-1.s, respectively, in the dog, and 4.53, 6.00, and 12.62
cmH2O.ml-1.s in the horse. At a given PL, Rcoll measured during inflation.
At constant PL, Rcoll increased with time at PL = 5 and 10 cmH2O, but was
not time dependent at PL = 20 cmH2O. At constant PL, Rcoll increased at
Vcoll increased. We conclude Rcoll is greater in horses than in dogs and is
a function of PL, Ps - PL, and lung volume history in both species.
