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

NCT ID: NCT07183605

Last Updated: 2025-11-25

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 30 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-09-22
• Study Completion Date: 2026-10-31

Brief Summary

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.

Detailed Description

Unfractionated heparin (UFH) is widely used in intensive care units (ICUs) and requires close monitoring, most commonly through the measurement of anti-Xa activity.

The reference method for anti-Xa monitoring involves blood sampling by peripheral vascular puncture. However, in ICU patients, peripheral access may be challenging or painful, and central venous catheters are often available and already used for UFH infusion. Sampling from these central lines could be a convenient alternative, but residual heparin in the catheter may contaminate the sample, leading to falsely elevated anti-Xa results.

The CASSANDRA study (Central catheter Anti-Xa Sampling Study for Accurate aNalysis and Reliable Dosage Assessment) is a prospective, monocentric, comparative study designed to assess whether anti-Xa activity levels obtained from central venous catheter samples are equivalent to those from peripheral vein samples.

To be eligible for inclusion, patients must already have a central venous catheter in place and require continuous intravenous unfractionated heparin administration through the distal lumen of the central venous catheter.

A three-way stopcock will be placed upstream of the infusion tubing to allow temporary interruption of UFH infusion during sampling.

Two 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).

For each patient, four pairs of simultaneous blood samples will be collected, according to a randomized sequence alternating between methods A and B. In each pair, one sample will be drawn from the central venous catheter and the other from a fresh peripheral vein puncture (reference). All anti-Xa assays will be performed, but only the results from peripheral vein samples (reference method) will be made available to clinicians. Anti-Xa results from central venous catheter samples will remain blinded to the clinical team to avoid influencing patient management.

The primary outcome is the absolute difference in anti-Xa activity between central venous catheter samples (either method) and peripheral samples. Equivalence is defined as a mean difference not exceeding 0.05 IU/mL. Secondary outcomes include Bland-Altman agreement limits between each central method and the peripheral reference.

Results of this study may support the safe use of central venous sampling for routine anti-Xa monitoring in ICU patients, provided an appropriate flushing method is used.

Conditions

Anticoagulants and Bleeding Disorders

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: DIAGNOSTIC
• Blinding Strategy: NONE

Study Groups

Sequence A, B, A, B

First and third samples with syringe flush; second and fourth with vacuum tube flush

Group Type: EXPERIMENTAL

catheter flushing techniques

Intervention Type: PROCEDURE

Two 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).

Sequence A, B, B, A

First and fourth samples with syringe flush; second and third with vacuum tube flush

Group Type: EXPERIMENTAL

catheter flushing techniques

Intervention Type: PROCEDURE

Two 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).

Sequence B, A, B, A

Second and fourth samples with syringe flush; first and third with vacuum tube flush

Group Type: EXPERIMENTAL

catheter flushing techniques

Intervention Type: PROCEDURE

Two 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).

Sequence B, A, A, B

Second and third samples with syringe flush; first and fourth with vacuum tube flush

Group Type: EXPERIMENTAL

catheter flushing techniques

Intervention Type: PROCEDURE

Two 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).

Interventions

catheter flushing techniques

Two 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).

Intervention Type: PROCEDURE

Eligibility Criteria

Inclusion Criteria

• 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
• Receiving continuous intravenous unfractionned heparin, with target Anti-Xa activity between 0.3 and 0.7 IU/ml.

Exclusion Criteria

• Protected person (under guardianship or curatorship)
• Person under court protection
• Person deprived of liberty
• Person not affiliated to the French social security
• Pregnant or breast-feeding woman

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Centre Hospitalier Régional d'Orléans

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Gregoire MULLER, Dr

Role: PRINCIPAL_INVESTIGATOR

CHU Orléans

Locations

Chu Orleans

Orléans, , France

Site Status: RECRUITING

Countries

France

Central Contacts

Gregoire MULLER, Dr

Role: CONTACT

gregoire.muller@chu-orleans.fr

+33238229534

Facility Contacts

Gregoire MULLER, PH

Role: primary

gregoire.muller@chu-orleans.fr

+33238229534

Other Identifiers

CHUO-2024-27

Identifier Type: -

Identifier Source: org_study_id