Contact Activation of Coagulation in Newly Inserted Central Venous Catheters

This is a randomized controlled trial, designed to evaluate coagulation activation in response to four different commercially available central venous catheters (CVCs), all with similar internal surface areas. The study focuses on comparing changes in coagulation parameters, primarily clotting time (CT), measured using rotational thromboelastometry (ROTEM® NATEM), as well as additional ROTEM variables and standard coagulation markers.

Participants are included based on clinical need for central venous access, and are randomized using REDCap to receive one of four CVC types:

• MERITMEDICAL Careflow™ Two-Lumen Catheter (7 Fr, 150 mm, polyurethane, OD 2.4 mm)
• ARROW Two-Lumen Catheter (7 Fr, 160 mm, polyurethane, OD 2.5 mm)
• ARROWg+ard Blue Plus® Two-Lumen Catheter (8 Fr, 160 mm, polyurethane, OD 2.8 mm, chlorhexidine/silver sulfadiazine coating)
• Multicath 2 Expert UP Two-Lumen Catheter (7.5 Fr, 160 mm, polyurethane shaft embedded with silver ions, OD 2.5 mm)

Blood samples will be collected at two time points for each participant:

• Sample 1: Immediately after catheter insertion, before flushing
• Sample 2: After at least 10 ml saline flush and discard protocol

All catheters will be inserted without pre-procedural filling with saline.

Blood will be collected into Vacuette® CTAD tubes (Greiner Bio-One, Kremsmünster, Austria) containing sodium citrate, theophylline, adenosine, and dipyridamole, designed for hemostatic testing. The tubes will be inverted eight times immediately after blood collection and kept at 37°C until processing. ROTEM® analysis will be performed within 3 hours of blood collection. After the ROTEM® analysis, the remaining blood will undergo centrifugation at 4000g for 15 minutes, and 600-700 µL of plasma from each sample will be transferred into cryotubes, which will be immediately frozen and stored at -80°C for further analysis.

Laboratory and ROTEM® Analyses

ROTEM® analyses will be performed on whole blood using recalcified non-activated thromboelastometry (NATEM), in accordance with the manufacturer's instructions. Each test will be run for 60 minutes, measuring the following variables:

Clotting Time (CT) - time to initial fibrin formation Clot Formation Time (CFT) - speed of thrombus development Alpha Angle (α-angle) - kinetics of clot formation Maximum Clot Firmness (MCF) - measure of final clot strength

Routine Plasma-Based Coagulation Assays:

Prothrombin Time-International Normalized Ratio (PT-INR) Activated Partial Thromboplastin Time (aPTT)

The following coagulation markers will also be assessed:

Factor VII (FVII) and Factor XII (FXII) Thrombin-Antithrombin Complex (TAT)

Inclusion criteria

Participants must meet all of the following criteria to be included in the study:

• Clinical indication for the placement of a two-lumen central venous catheter with length 150-160 mm.
• Age ≥18 years.
• Signed informed consent.

Exclusion criteria

Participants meeting any of the following criteria will be excluded:

• Current use of anticoagulants or platelet inhibitors, except: Prophylactic low molecular weight heparin (LMWH), double prophylactic dose of LMWH, Acetylsalicylic acid (ASA).
• Prothrombin complex (pK/INR) outside the normal range (0.9-1.2), platelet count <50 × 10⁹/L or haemoglobin < 80 g/L, if already available.
• Known coagulopathic conditions, including but not limited to:

• Activated protein C (APC) resistance,
• Hemophilia A or B,
• Vitamin K deficiency,
• Disseminated intravascular coagulation (DIC),
• Antiphospholipid syndrome,
• von Willebrand disease, Other known congenital or acquired bleeding disorders.