Journal of Applied Physiology, Vol 38, Issue 4 675-680, Copyright © 1975 by American Physiological Society
Effects of lung inflation on pulmonary arterial blood volume in intact dogs
A. Wanner, S. Zarzecki and M. A. Sackner
The isolated effects of alterations of lung inflation and transmural
pulmonary arterial pressure (pressure difference between intravascular and
pleural pressure) on pulmonary arterial blood volume (Vpa) were
investigated in anesthetized intact dogs. Using transvenous phrenic nerve
stimulation, changes in transmural pulmonary arterial pressure (Ptm) at a
fixed transpulmonary pressure (Ptp) were produced by the Mueller maneuver,
and increases in Ptp at relatively constant Ptm by a quasi-Valsalva
maneuver. Also, both Ptm and Ptp were allowed to change during open airway
lung inflation. Vpa was determined during these three maneuvers by
multiplying pulmonary blood flow by pulmonary arterial mean transit time
obtained by an ether plethysmographic method. During open airway lung
inflation, mean (plus or minus SD) Ptp increased by 7.2 (plus or minus 3.7)
cmH2O and Ptm by 4.3 (plus or minus 3.4) cmH2O for a mean increase in Vpa
by 26.2 (plus or minus 10.7) ml. A pulmonary arterial compliance term
(Delta Vpa/Delta Ptm) calculated from the Mueller maneuver was 3.9 ml/cmH2O
and an interdependence term (Delta Vpa/Delta Ptp) calculated from the
quasi-Valsalva maneuver was 2.5 ml/cmH2O for a 19% increase in lung volume,
and 1.2 ml/cmH2O for an increase in lung volume from 19% to 35%. These
findings indicate that in normal anesthetized dogs near FRC for a given
change in Ptp and Ptm the latter results in a greater increase of Vpa.
