Journal of Applied Physiology, Vol 53, Issue 2 483-489, Copyright © 1982 by American Physiological Society
Constant-flow ventilation of apneic dogs
B. E. Lehnert, G. Oberdorster and A. S. Slutsky
The adequacy of constant airway gas flow sustenance of arterial blood gas
tensions was investigated in anesthetized-paralyzed mongrel dogs. Gas
delivery was achieved via a main-stem bronchi cannulation system
constructed of two polyethylene tubes bifurcating at the carina, which
rested on the posterior surface of the trachea outside of an endotracheal
tube positioned in the upper third of the trachea. Equal flows (total flow
= Vin) of humidified air were delivered through each limb of the
cannulation system at constant flow rates with Vin ranging from 8 to 28
l/min. Intratracheal pressures at these flows characteristically ranged
from 0.1 to 1 cmH2O. Arterial O2 tension varied directly (PaO2 = 0.72 Vin +
74.6), and arterial CO2 tension varied inversely (PaCO2 = -0.73 Vin + 51.2)
with Vin during ambient gas, constant-flow ventilation (CFV). During
prolonged CFV (greater than 2 h), no evidence of CO2 accumulation or
deterioration of PaO2, was observed. This study demonstrates that in apneic
dogs normal blood gases can be achieved and maintained over prolonged
periods with constant airway flow at low intratracheal pressures.
