Journal of Applied Physiology, Vol 65, Issue 4 1598-1603, Copyright © 1988 by American Physiological Society
Correction of inert gas washin or washout for gas solubility in blood
E. A. Harris and R. M. Whitlock
Department of Clinical Physiology, Green Lane Hospital, Auckland, New Zealand.
We show that when an inert gas is washed into the lungs its retention in
the blood during any one breath is approximately proportional to its
solubility. This relationship makes possible the correction of washin or
washout data for blood uptake or release, provided that two gases of
different solubility are used simultaneously. The method automatically
allows for the characteristics of an individual washin or washout and for
the occurrence of recirculation within a fairly short washin or washout
period. It has been tested in models with nonuniform ventilation and
perfusion and closely approximates the behavior of a truly insoluble gas.
In the derived ventilation distribution, gas solubility appears as
ventilation to units of low turnover. In the case of N2 this effect is
small but causes appreciable overestimation of lung volume. The recovered
dead space and main alveolar distribution are insignificantly affected.
