Artifact of blood pressure recording using heparin-filled catheter: effects on blood pressure and coagulation parameters.

ABSTRACT

A usual complication of catheterization procedures of arteries for blood pressure recording is the clogging of catheters due to activation of coagulation. This is usually avoided by filling the catheters with a heparinized saline solution. We have studied rats implanted with four catheters, one of which was used to monitor blood pressure for 6 h. Catheters were filled with 100 IU/ml heparin in saline. Using this standard protocol, approximately 50-200 IU of heparin were injected into the animals. This induces significant anticoagulation. The activated partial thromboplastin time (APTT) increased from 27 s to more than 240 s. We devised a modified "low heparin" protocol, in which the concentration of heparin in the wash solution of the catheters was lowered from 100 to 0.1 IU/ml, and the pressor transducer was back-perfused with saline solution without heparin. Using this new protocol, no significant modification of the APTT was observed, indicating that only trace amounts of heparin were injected. Subsequent controlled administration of heparin induced a significant decrease in blood pressure. To avoid all effects associated with this unwanted infusion of heparin, mainly a decrease in blood pressure and a major anticoagulant effect, we suggest the use of such "low heparin" catheterization protocol.