The effect of heparin and of acid-citrate-dextrose solution on screen filtration pressure of blood in experimental hypotension.

Anticoagulation with heparin may not always adequately protect an ischaemic vascular bed. A screen filtration device has been employed to study the in vitro actions of acid-citrate-dextrose (ACD) and heparin on blood from the dog in haemorrhagic shock. With both anticoagulants, blood obtained during shock caused greater filter obstruction than blood taken before shock. However, the increased obstruction was nearly four times greater with heparinized blood than with acid-citrate-dextrose blood. These findings suggest that the anticoagulant action of heparin may be markedly diminished in low blood flow states.