Journal of Applied Physiology, Vol 61, Issue 5 1836-1842, Copyright © 1986 by American Physiological Society
CO2 elimination by high-frequency oscillation: effects of vagosympathetic stimulation
J. M. Drazen, I. Dreshaij, R. H. Ingram Jr, M. Khoo, R. Kamm and J. Solway
The effects of electrical stimulation of the vagi on gas transport mediated
by high-frequency, low tidal volume ventilation (HFV) was examined in 10
anesthetized, paralyzed, propranolol-treated dogs. Gas transport efficiency
was estimated by measuring the rate of CO2 removed from the lungs (Vco2)
achieved during 45-s bursts of HFV applied before (control 1), during, and
after (control 2) electrical stimulation of the transected vagi. During
vagal stimulation the heart rate was maintained by electrical pacing.
During the 15-s phase of vagal stimulation pulmonary impedance increased
from 3.6 +/- 0.7 to 6.2 +/- 2.2 cmH2O X l-1 X s, and Vco2 increased. When
the electrical stimulation of the vagi was stopped, impedance and Vco2
returned to prestimulation values. Vco2 was always higher during electrical
stimulation of the vagi when HFV of a fixed volume was applied over a range
of frequencies or when a fixed oscillation frequency was used over a range
of tidal volumes. The effects of vagal stimulation on HFV-mediated gas
transport were quite similar to the effects of moving the locations of the
bias flow inlet and outlet into the lung such that tracheal volume was
decreased by 20 ml, an amount equivalent to estimated change in control
airway volume thought to occur during vagal stimulation. We simulated the
effects of vagal stimulation and decreased tracheal volume on Vco2 by using
a previously described model of HFV-mediated gas transport.(ABSTRACT
TRUNCATED AT 250 WORDS)
