Journal of Applied Physiology, Vol 44, Issue 2 291-296, Copyright © 1978 by American Physiological Society
Functional residual capacity and body position in the dog
V. D. Minh, G. F. Dolan, B. B. Brach and K. M. Moser
Resting lung volumes in the supine position (FRCs) were determined by N2
washout method in 67 dogs under pentobarbital anesthesia and computed in
ml/kg body weight (BW). In 21 other dogs, FRCs and the change in FRC from
the supine to upright positions (deltaFRC) were determined; these lung
volumes were expressed in ml/kg BW and in percentage of TLC40 (lung volume
at 40 cmH2O positive-pressure inflation). It was found that a) FRCs
averaged 38.6 plus or minus 8.2 and 42 plus or minus 5.9 ml/kg BW in the
two groups of dogs; b) deltaFRC averaged 23 plus or minus 4 ml/kg BW
resulted in large data dispersion, a large coefficient of variation (CV)
and a poor correlation (r) of lung volume to BW; D) on the contrary, marked
uniformity of FRCs and FRCu (upright FRC) was obtained by expressing the
resting lung volumes in %TLC40, allowing an accurate prediction of FRC from
the inspiratory capacity (IC). Relationship of FRCu to TLC was comparable
to human data reported in the literature. FRCs (%TLC40) was smaller than
values previously reported for awake human subjects, probably due to the
FRCs reduction in our dogs by anesthesia.
