The goal is to investigate whether blood samples drawn from a central venous catheter can provide reliable measurements of 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.
To evaluate the reliability of central venous blood sampling, the study will compare anti-Xa activity levels obtained simultaneously from two different types of blood draws: one from a peripheral vein (reference method), and the other from the central line using one of two flushing techniques.
The two central flushing techniques being studied are:
* A 5 mL syringe flush performed over 5 seconds, followed by blood collection. * A vacuum tube flush that draws and discards 5 mL of blood, followed by blood collection.
Each patient will undergo four pairs of simultaneous blood draws, using both central techniques in a randomized sequence. The main objective is to assess whether the anti-Xa levels from central samples are equivalent to those from peripheral vein puncture, with a predefined margin of equivalence of ±0.05 IU/mL.
Findings from this study may support the use of central venous catheters for routine anti-Xa monitoring in ICU patients, potentially avoiding painful or technically difficult peripheral vein punctures.
Person (or support person/relative if unable to do so) who has agreed to participate in the study
18 years of age or older
Hospitalized in intensive care medicine
Having a central venous catheter with at least three lumens (internal jugular, subclavian or femoral) already in place
Protected person (under guardianship or curatorship)
Person under court protection
Person deprived of liberty
Person not affiliated to the French social security
Parallel
catheter flushing techniques
Procedure/SurgeryTwo catheter flushing techniques will be compared: * Method A: A 5 mL flush performed with a syringe over 5 seconds. * Method B: A 5 mL flush using a vacuum tube (standard discard tube).
Difference in anti-Xa activity values between the two sampling sites.
Difference in anti-Xa activity values between the two sampling sites: central venous catheter with a 5 mL discard using either a syringe or a vacuum tube, versus peripheral vein puncture, the latter being considered the reference method. Equivalence is defined a priori as a mean absolute difference not exceeding 0.05 IU/mL of anti-Xa activity.
Equivalence of anti-Xa activity measurements between central venous catheter sampling using flush method A (5 mL syringe discard) and peripheral vein puncture.
Agreement limits of anti-Xa activity measurements between central venous catheter sampling using flush method A and peripheral vein puncture.
Equivalence of anti-Xa activity measurements between central venous catheter sampling using flush method B (5 mL vacuum tube discard) and peripheral vein puncture.
Agreement limits of anti-Xa activity measurements between central venous catheter sampling using flush method B and peripheral vein puncture. In both cases, the anti-Xa activity measured from the peripheral vein is considered the reference
Types and durations of organ support therapies
Organ support requirements, including number of days on mechanical ventilation, renal replacement therapy, or extracorporeal membrane oxygenation (ECMO).
Thromboembolic and bleeding complications
Description of thrombotic and bleeding complications during the ICU stay, with bleeding events graded according to ISTH severity criteria.
Types of blood products transfused
Type of blood products transfused (red blood cells, frozen plasma, platelets) during the ICU stay will be recorded.
Number of blood products transfused
Number of blood products transfused during the ICU stay.
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