Intravascular and extravascular pulmonary fluid volumes during acute experimental pericardial tamponade.

Pulmonary congestion is usually absent in cardiac tamponade. To examine the effects of experimental pericardial tamponade on pulmonary fluid volumes, we studied 14 anesthetized dogs with indicator-dilution techniques to measure extravascular (EVLW) and intravascular (PBV) pulmonary fluid volumes. Seven dogs were studied at two levels of tamponade and seven were studied during two levels of left atrial (LA) hypertension produced with an LA balloon. EVLW and PBV were measured in both groups at control state and then at two levels of elevated LA pressure (P). When LAP was raised by the balloon, PBV rose with the increase in LAP (4.9 +/- 2 cc/kg control at LAP 1.2 +/- 1.0 mm Hg versus 6.8 +/- 2.1 cc/kg at LAP 8.4 +/- 1.4 mm Hg and 6.8 +/- 2.1 cc/kg at LAP 14.7 +/- 2.0 mm Hg; both intervention PBV values p less than 0.01 vs control). During tamponade, PBV did not change (4.1 +/- 1.1 cc/kg at LAP 1.3 +/- 2.2 mm Hg control versus 4.4 +/- 1.0 cc/kg at LAP 7.4 +/- 1.4 mm Hg and 4.8 +/- 1.3 cc/kg at LAP 12.7 +/- 2.8 mm Hg). EVLW changes were similar during elevation of LAP in both groups (tamponade dogs 7.1 +/- 2.6 cc/kg, 7.1 +/- 1.6 cc/kg and 8.9 +/- 2.1 cc/kg, respectively; and LA hypertension dogs 6.9 +/- 2.5 cc/kg, 7.3 +/- 2.0 cc/kg, and 8.0 +/- 2.0 cc/kg, respectively. We conclude that during cardiac tamponade there is little change in PBV in response to rises in LAP. This is significantly different from the changes seen when increasing LAP by inflating an LA balloon, where fluid is shifted from the peripheral to the central circulation. EVLW changes were similar for the two methods during elevation of LAP.