Fluid shifts in the cat lung during cardiogenic shock

Transcapillary fluid shifts after experimental myocardial infarction were measured in cats by double-isotope technique. In the control animals, pulmonary extravascular volume increased 49.2% after infarction, and intravascular volume decreased 15.8%. There was evidence of hemoconcentration, with an increase in hematocrit and a fall in plasma volume. Administration of the proteolytic enzyme inhibitor aprotinin following infarction reduced the fluid shift into the extravascular space significantly. It is concluded that the increase in pulmonary extravascular volume frequently seen after myocardial infarction is not solely the result of low output failure but may in part reflect changes in capillary permeability secondary to enzymatic damage.