Journal of Applied Physiology, Vol 65, Issue 3 1281-1285, Copyright © 1988 by American Physiological Society
Measurement of alveolar gas volume by ambient pressure changes in isolated lungs
R. R. Martin, R. Peslin, C. Duvivier and C. Gallina
Institut National de la Sante et de la Recherche Medicale Unite 14, Laboratoire de Physiopathologie Respiratoire, Vandoeuvre-les-Nancy, France.
Alveolar gas volume (AGV) may be measured in humans (Peslin et al., J.
Appl. Physiol. 62: 359-363, 1987) by applying very slow sinusoidal
variations of ambient pressure (delta Pam) around the body and studying the
relationship between delta Pam and the resulting gas displacement at the
mouth (delta Vaw): AGVapc = (PB.delta Vaw)/(delta Pam.cos phi), where
AGVapc is AGV measured by ambient pressure changes, PB is barometric minus
alveolar water vapor pressure, and phi is the phase angle between Pam and
Vaw. The applicability of this method to excised lungs at various
transpulmonary pressures was assessed in six rabbit lungs and three dog
lobes by reference to AGV measurements by He dilution (AGVdil) and by a
volumetric method (AGVvol). Except in one instance, AGVapc did not change
significantly when the frequency of delta Pam was varied from 0.02 to 0.2
Hz. AGVapc was highly correlated (P less than 0.001) to both AGVdil and
AGVvol. It did not differ significantly from AGVdil (81.4 +/- 50.6 vs. 80.2
+/- 44.2 ml) and was only marginally higher than AGVvol (64.6 +/- 26.9 vs.
62.4 +/- 24.4 ml, P less than 0.05). We conclude that the method usually
provides accurate results in excised lung preparations. Its main advantages
are that it does not require manipulating the lung or changing its volume
and that the measurement takes less than 1 min.
