Journal of Applied Physiology, Vol 52, Issue 3 725-733, Copyright © 1982 by American Physiological Society
Pulmonary impedance in dogs measured by forced random noise with a retrograde catheter
J. M. Fullton, D. A. Hayes and R. L. Pimmel
Retrograde catheter and forced random noise techniques were combined to
study the distribution of resistance and compliance in dogs following the
inhalation of aerosols containing 2.5 and 5.0 mg/ml of histamine. Mean
base-line peripheral resistance was 0.367 cmH2O . l-1 . s, agreeing with
previous estimates. After correction for the endotracheal tube, the mean
central airway resistance was 0.040 cmH2O . l-1 . s, considerably lower
than previous estimates. This discrepancy was attributed to an
overcorrection for the endotracheal tube resistance. The lower histamine
dose caused a substantial increase in peripheral resistance, a relatively
small increase in central resistance, and substantial decreases in total
and peripheral compliance. After the higher histamine dose, changes in
peripheral resistance and both compliances were similar to those obtained
with the lower dose; however, the increase in central resistance was much
larger than at the lower dose. The difference between total and peripheral
compliance yielded estimates of airway compliance of 0.00306 l/cmH2O before
and 0.00104 l/cmH2O after 2.5 mg/ml of histamine.
