Journal of Applied Physiology, Vol 79, Issue 4 1320-1329, Copyright © 1995 by American Physiological Society
Effects of ventilation and pleural effusion on measurements of airway thermal volume and blood flow in dog lungs
A. Kano, K. Kambara, M. Arakawa, F. Ando, M. Ohno, M. Tsuchiya, K. Nishigaki and H. Fujiwara
Second Department of Internal Medicine, Gifu University School of Medicine, Japan.
We studied the effects of ventilation and pleural effusion on measurements
of airway thermal volume (ATV) and pulmonary blood flow (PBF) by using the
airway gas thermometry method of V. B. Serikov, M. S. Rumm, K. Kambara, M.
I. Bootomo, A. R. Osmack, and N. C. Staub (J. Appl. Physiol. 72: 944-953,
1992) in 39 anesthetized dogs with or without lung edema or pleural
effusion. To examine the differential effects of increased-pressure and
increased-permeability lung edema on accuracy and sensitivity of ATV and
PBF, two models of lung edema were induced by intravenous infusion of a
Dextran 70 solution and alloxan monohydrate, respectively. Dogs were
hyperventilated for 3 min by using a wide range of minute ventilation (VE)
to produce two steady-state conditions of airway temperature. Higher levels
of VE increased an estimated amount of ATV. The ATV produced by
hyperventilation at VE values of 559, 158, and 72 ml.min-1.kg-1 was
consistent with the gravimetric total lung mass, the blood-free wet lung
weight, and the extravascular lung water volume, respectively. The
coefficient of lung thermal conductivity, a practical index of the rate of
heat conduction through tissue from lung vessels, was related to the ratio
of the decrease in expired air temperature to VE, and estimated PBF was
consistent with the thermodilution cardiac output. Pleural effusion had
little effect on measurements of ATV and PBF. However, ATV and PBF showed
increased variation in dogs with dextran-induced lung edema.
