Jc. Newell et al., ASSESSMENT OF ACUTE PULMONARY-EDEMA IN DOGS BY ELECTRICAL-IMPEDANCE IMAGING, IEEE transactions on biomedical engineering, 43(2), 1996, pp. 133-138
Acute pulmonary edema was assessed quantitatively in 12 experiments on
six anesthetized dogs. Thirty-two copper foil electrodes were placed
around each animal's thorax at the level of the third intercostal spac
e. A real-time electrical impedance tomograph was used to form images
of the electrical admittivity of the thorax in and near the plane of t
hese electrodes, The lungs were identified by studying the change in a
dmittivity associated with inspiration. Mean admittivity in these lung
regions was assessed at 40-min intervals for the next 36 hours. In si
x control experiments, each having a duration of 200 min, the initial
admittivity of the lung regions was 102 +/- 16(SD) mS/m, Lung admittiv
ity usually increased during the first 80 min, and then remained withi
n 2 mS/m of its value at 80 min for the remaining 120 min. In six expe
riments with pulmonary edema, an initial period of change followed by
stability was observed, When stability had been attained, 0.07 ml/kg o
f oleic acid was injected slowly into a central venous site, Five anim
als received oleic acid, the sixth received a sham injection of saline
, In the five receiving oleic acid, lung admittivity rose steadily for
the remainder of the experiment. The increase in lung admittivity in
these five animals was between 4 and 16 mS/m. In the sham injected exp
eriment, the lung admittivity changed by 1 mS/m, We conclude that impe
dance imaging can provide semiquantitative assessment of the developme
nt of acute pulmonary edema.