Bloody pericardial fluid. The value of blood gas measurements.

Clinically notable pericardial effusions developed in three patients with renal failure. Pericardiocentesis showed hemorrhagic fluid, the source of which was not apparent. Simultaneous determinations of PCO2, PO2, and pH values showed a substantial increase in PCO2 levels and decrease in PO2, pH, and bicarbonate levels in the pericardial compared with the intracardial aspirates. This was true when pericardial fluid PCO2, PO2, and pH values were compared with mixed venous samples. Determination of PO2, PCO2, pH, and bicarbonate values in pericardial aspirates may determine the source of the fluid.