Journal of Applied Physiology, Vol 69, Issue 1 281-292, Copyright © 1990 by American Physiological Society
A statistical model of the VA/Q distribution
L. L. Lim
Department of Applied Statistics, University of Reading, Berkshire, United Kingdom.
A "blocks model" is proposed to model the distribution of the
ventilation-perfusion ratio (VA/Q distribution). This model is developed
from statistical principles and enables the estimated VA/Q distribution to
be interpreted in a straightforward and intuitive manner. Estimation of
parameters of the blocks model uses a constrained weighted least-squares
procedure. Although developed initially to estimate VA/Q distributions from
data generated by the multiple inert gas elimination technique (P. D.
Wagner, H. A. Saltzman, and J. B. West, J. Appl. Physiol. 36: 588-599,
1974), the blocks method is applicable to any problem in which the unknown
distribution is related to the data through an ill-posed integral equation
and is particularly suited for problems in which the data are scarce. The
method is illustrated with several examples--hypothetical data representing
a wide range of VA/Q distributions as well as some real data.
