Heparin release kinetics in blood gas syringes

Background: In view of the urgency of results quality and operational availability of point of care analyzers is of high importance in ICUs and operational theatres. Methods: We investigated the influence of time on release and total amount of Heparin in various types of syringes used for blood gas analysis (BGA). Heparin activity in three types of liquids (electrolyte solution, fresh frozen plasma and whole blood) was quantified in its time dependency. The ability of clot formation was measured with rotation thrombelastography in whole blood. All tests were done with three types of preanalytical procedures (�resting�, �rolling� and �rotating�). Results: We found different time dependencies of heparin activities in syringes releasing dried heparin from pads, the inner syringe wall or liquid heparin solutions during the first 20 minutes after liquid aspiration. The heparin activities lie in a wide range below or above their nominal content in 200µl aliquots withdrawn from the BGA-samples. Preananlytical treatment has influence particularly on the range of heparin activity during the first 10 minutes. Conclusion: The risk of blockages by clots in analyzers is lower when syringes with liquid heparin or heparin dried at the inner syringe wall are used