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NCT Number: NCT07365670

Comparison of the Best Method for Measuring Anti-Xa Activity in Children Receiving Unfractionated Heparin in Cardiac Intensive Care (COMPAXE-HNF)

This study aims to compare the accuracy of two different blood sampling methods from a central venous catheter (CVC) for measuring anti-Xa activity in children receiving unfractionated heparin (UFH) from this CVC. The results will be compared to a "gold standard" sample taken from an arterial catheter (KTA) whithout UFH. The objective is to identify a more reliable method for monitoring UFH, thereby reducing the risk of bleeding or thrombosis in these patients.

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Key information

Conditions

Congenital Heart Disease Anti Xa Activity Cardiovascular Abnormalities Cardiovascular Diseases Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Embolism and Thrombosis Heart Defects, Congenital Heart Diseases Thrombosis Unfractionated Heparin Vascular Diseases

Age range

1 day–17 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

About this study

  • Scientific Justification: UFH is widely used in pediatric cardiac intensive care for its short half-life and availability of an antidote. However, monitoring its effect via anti-Xa activity is challenging. The standard method of sampling from a CVC is known to be prone to heparin contamination, leading to inaccurate results (over- or under-anticoagulation). This lack of precision can lead to dangerous complications like major bleeding or thrombotic events. As studies by Palermo et al. (1980) and Bauman et al. (2012) have shown, the unreliability of CVC samples justifies the search for a safer alternative. The arterial catheter (KTA) provides a contamination-free "gold standard," making it the ideal comparison for evaluating the more reliable sampling method.
  • Procedure: The study will compare two CVC sampling methods (a standard flush protocol and a new experimental method) against the gold standard (KTA sampling without UFH)
  • Follow-up: The study will be conducted over three consecutive days. Each day, three sets of blood samples will be collected every 6 hours per patient (KTA, standard CVC, and experimental CVC).

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Minors aged 0 to 17 inclusive
  • Weight greater than or equal to 3.5 kg
  • Admitted to resuscitation or congenital cardiac intensive care
  • Requiring treatment with unfractionated heparin at curative doses administered via central venous access
  • Equipped with a central arterial and venous catheter
  • Affiliated with or beneficiary of a social security scheme
  • Free, informed, and written consent signed by one of the two representatives of parental authority and the investigator (no later than the day of inclusion and before any examination required by the research).

Exclusion criteria

  • Newborns < 37 weeks gestation
  • Patients treated by a humanitarian organization

Treatment and study plan

blood sampling for measuring anti-Xa activity

Procedure

Each patient included in the study will have a series of three samples taken every 4 hours for 3 days:

  • Sample taken from a non-heparinized arterial catheter (Gold Standard), performed as part of routine care: Method ①
  • Sample taken from a central venous catheter without stopping the HNF: Method ②
  • Sampling from a central venous catheter with an HNF pause: Method ③

At each anti-Xa activity check in the included patients, the nurse will take the 3 blood samples.

The order in which samples ② and ③ are taken will be determined by randomization.

measurement of anti-XA activity

Procedure

Each patient will have, each time that anti-Xa activity needs to be measured, three successive samples taken:

  • Sample taken from a non-heparinized arterial catheter (gold standard), performed as part of routine care: Method ①
  • Sample taken from a central venous catheter without stopping the HNF: Method ②
  • Sample from central venous catheter with HNF pause: Method ③

Primary outcomes

  1. Measurement of anti-Xa activity (in IU/mL) from two samples (with and without HNF pause) taken from the central venous line where HNF is administered, compared to a sample taken from a non-heparinized arterial catheter (i.e., gold standard).

    Time frame: "From enrollment to the end of study at 72hours"

    Anti-Xa activity and APTT measurements will be performed at the university hospital's central laboratory, which guarantees the consistency of the reagents, automated systems, and techniques used.

    The recommended therapeutic target is between 0.3 and 0.6 IU/mL.

Secondary outcomes

  1. Measurement of APTT from two samples (with and without HNF pause) taken from the central venous line where HNF is administered, compared to a sample taken from a non-heparinized arterial catheter (i.e., gold standard).

    Time frame: "From enrollment to the end of study at 72 hours"

    Activated partial thromboplastin time (APTT):

    Mainly used in the United States and in some French intensive care units, the APTT provides an overall assessment of the activity of several coagulation factors: factor I (or fibrinogen), factor II (or prothrombin), factor V, factor VIII, factor IX, factor X, factor XI, and factor XII. (Figure 1) The APTT is a measure of blood clotting time. It is expressed as a ratio between the patient's APTT and a "control" APTT, which is that of the laboratory. It is expressed in seconds.

    Normal values for the patient APTT/control APTT ratio are between 0.80 s and 1.20 s.

    • Above this range: the risk of bleeding increases.
    • Below this range: treatment is ineffective, with a risk of clot formation.

  2. Measurement of APTT and anti-Xa activity (in IU/mL) from a sample taken from a non-heparinized arterial catheter (i.e., gold standard)

    Time frame: From enrollment to the end of study at 72 hours

    The TCA measurement is performed in the same way.

Study contacts

Contact information is provided by the study sponsor or research team.

Marie CONEAU

CONTACT

[email protected]

+262693829524

Sponsors and collaborators

Lead sponsor

Centre Hospitalier Universitaire de la Réunion

Other

Registry information

Acronym: COMPAXE-HNF

Important dates

Study start
2026
Primary completion
2029
Study completion
2029
First posted
Jan 26, 2026
Registry last updated
Jan 26, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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