Journal of Applied Physiology, Vol 49, Issue 2 337-341, Copyright © 1980 by American Physiological Society
Peribronchial electrical admittance measures lung edema and congestion in the dog
J. E. McNamee and M. L. Brodman
A new method has been developed to detect interstitial pulmonary edema.
This method utilizes the unique arrangement of air and interstitial fluid
within the lung. A 1.3-mm-diam twin catheter electrode was wedged in a
peripheral airway of the lung. The electrical impedance measured at 35 kHz
between these catheter-tip electrodes was 1,540 +/- 240 omega (mean +/- SD;
n = 10) in the anesthetized closed-chest dog. Intravenous infusion of 1-3
liters 0.154 M NaCl increased extravascular water per gram of dry lung from
a control value of 3.54 +/- 0.27 to 4.1-5.14. Peribronchial electrical
impedance decreased in proportion to the amount of saline infused reaching
a minimum of 550 omega. No signs of alveolar flooding were present during
the experiments. Linear regression performed on peribronchial electrical
admittance (PEA) as a function of extravascular water per gram of dry lung
(ELW) resulted in the following relationship: PEA = 0.72 ELW - 1.81; r =
0.95. It is concluded that this method is a sensitive quantitative measure
of lung interstitial fluid and can detect pulmonary edema and congestion in
the dog lung before alveolar flooding occurs.
