Central Catheter Anti-Xa Sampling Study for Accurate aNalysis and Reliable Dosage Assessment

What this Trial Is About

Researchers are investigating whether blood samples drawn from a central venous catheter can reliably measure unfractionated heparin (UFH) anti-Xa activity compared to the standard method of peripheral vein puncture in intensive care unit (ICU) patients receiving continuous intravenous UFH. The study aims to determine if central venous catheter sampling could be a less painful and more convenient alternative for monitoring anti-Xa activity, which is important for safe UFH dosing in ICU patients. The study compares two flushing techniques used in central venous catheter blood sampling: Method A involves a 5 mL syringe flush performed over 5 seconds, and Method B uses a 5 mL vacuum tube flush that discards blood before collection. Each patient undergoes four pairs of simultaneous blood draws, alternating between the two flushing methods in a randomized sequence. One sample in each pair is collected from the central catheter and the other from a peripheral vein, which serves as the reference for comparison. Participants will have their anti-Xa activity levels measured from both central and peripheral samples, but only the peripheral results will be shared with clinicians. The main outcome is the difference in anti-Xa activity between the two sampling sites, with equivalence defined as a mean difference within ±0.05 IU/mL. Secondary outcomes assess agreement limits between methods. Blood draws occur up to Day 28 after inclusion. The study may support using central catheters for routine anti-Xa monitoring if reliable results are confirmed, reducing the need for peripheral vein punctures.

Comparison of Heparin Anti-Xa Activity From Central Venous Catheter Samples Using a 5 mL Syringe Flush or a Vacuum Tube Flush Versus Peripheral Vein Samples in ICU Patients