Circulation, Vol 76, 843-849, Copyright © 1987 by American Heart Association
JI Sznajder, E Evander, ER Pollak, C Becker and AG Little
The pulmonary effects of pericardial effusion were studied in eight
anesthetized dogs, with emphasis on lung mechanics, O2 exchange, and
extravascular thermal lung volume (ETV) accumulation, while warm saline was
instilled into the pericardium to elevate pericardial pressure. The results
were compared with those from four time-controlled and sham- operated dogs.
ETV, as measured by a double-indicator technique, increased from 8.1 +/-
0.8 ml/kg at a pericardial pressure of 0 mm Hg to 12.9 +/- 2.1 ml/kg at
11.0 mm Hg (p less than .01). In the control group, ETV increased from 6.5
+/- 0.7 to 8.2 +/- 0.5 ml/kg over an equal time span. This increase in ETV
in the experimental dogs was inversely related to pulmonary compliance,
which decreased by 29% as ETV increased (p less than .05), whereas in the
time-controlled group of animals it decreased by 8.8%. Arterial PO2 did not
deteriorate during the protocol in either group. Histologic examination
showed increased interstitial fluid, but neither alveolar fluid nor septal
edema, and gravimetric measurements of lung liquid were also consistent
with interstitial fluid accumulation in experimental but not control
animals. These findings are concordant with the clinical observation that
alveolar edema is rarely seen in the presence of pericardial tamponade.
Conceivably, progression from interstitial to alveolar edema did not occur
both because of the low pulmonary blood flow that occurs as part of
pericardial tamponade physiology and/or because the hydrostatic pressures
were not elevated enough to produce higher rates of fluid transudation.
ARTICLES
Pericardial effusion causes interstitial pulmonary edema in dogs
Department of Surgery, University of Chicago Hospitals, IL 60637.
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