Multifibren u

The primary evaluated parameter was the preoperative serum fibrinogen level, which were measured within 48 hours of surgery by the Clauss method using the BCS analyzer (Multifibren U; Siemens Healthcare, Erlangen, Germany). The normal range of serum fibrinogen level was 1.80–3.50 g/L. Co-variates for multivariable adjustment were obtained from the clinical records as well as the linked clinical inspection database of the hospital.
Covariate were chosen based on the previously published Cleveland Clinic^{5 (link)}, the Metha⁶ and the Birnie scores^{8 (link)} for predicting AKI following cardiac surgery, as well as others related to surgery. The covariates were: age, sex, co-morbidities (hypertension, diabetes mellitus, cerebrovascular disease, obesity), surgery characteristics (elective or emergency; valve replacement surgery only, combined valve replacement surgery and others; prior cardiac operation), and preoperative markers (LVEF; eGFR; serum creatinine; HB; INR). Age was grouped into three categories: ≤60 years, 61 to 75 years, and >75 years. Obesity was defined as body mass index (BMI) ≥28.00 kg/m². Preoperative LVEF was grouped as good ≥50.00%, fair 30.00 to 49.99%, or poor <30%. eGFR was grouped as ≤30.00, 30.01 to 60.00, 60.01 to 90.00, and >90 mL/min/1.73m². HB was grouped as ≤100, 101 to 120, and >120 g/L. INR was grouped as ≤0.90, 0.91 to 1.10, and >1.10.

Markers of inflammation (blood cell counts, CRP, SAA, Club cell protein (CC16), IL-6) and coagulation (prothrombin F 1.2, endothelial microparticles, fibrinogen, D-dimers) were analyzed. The total and differential blood cell counts were determined using standard procedures with UniCell DxH800 (Beckman Coulter Inc., Brea CA, USA). Sandwich ELISA were used to measure CC16 (BioVendor, Brno, Czech Republic, range 1.57-50 ng/mL), IL-6 (R & D Systems, Wiesbaden, Germany, range 4.7-600 pg/mL), SAA (Invitrogen™ Novex ™ SAA Human ELISA Kit which detect serum amyloid A1 cluster, Carlsbad CA, USA, range 9.4-600 ng/mL), and CRP (high sensitive ELISA from Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany, precision levels down to or below 0.3 mg/L) in serum.
The clotting factors were measured in plasma according to the manufacturer’s instructions: Prothrombin cleavage fragment F1.2 with Enzygnost F1.2 (Siemens, range 69-229 pmol/L), endothelial microparticles with ZYMUPHEN MP (Hyphen Biomed, Neuville-sur-Oise, France, precision levels down to or below 5 nM), fibrinogen with a modified method from Clauss with Multifibren U (Siemens, range 180-350 mg/dL), and D-dimers with Behring Coagulation System XP (BCS XP) and INNOVANCE D-Dimer (Siemens, precision levels down to or below 0.5 mg/L).

Blood samples were drawn from antecubital veins, with minimal stasis. The complete blood cell count, lipid profile, glucose, and creatinine were assayed by routine laboratory techniques. High-sensitivity C-reactive protein (hsCRP) and Lp(a) were determined using immunoturbidimetry (Roche Diagnostics, Mannheim, Germany). Fibrinogen was measured using the Clauss method (Multifibren U, Siemens Healthcare, Marburg, Germany). Factor II activity was determined using a coagulometric method (Thromborel S, Siemens Healthcare). Plasma α2-antiplasmin and plasminogen were measured by chromogenic assays (Siemens Healthcare). Commercially available ELISA tests were used to determine TF antigen (Zymutest Total Tissue Factor Antigen), PAI-1 Antigen (Zymutest PAI-1 Antigen), and thrombin activatable fibrinolysis inhibitor (TAFI) zymogen (Zymutest Activatable TAFI, all Hyphen BioMed, Neuville-Sur-Oise, France).
To evaluate fibrin clot properties and thrombin generation, blood samples were mixed with 3.2% sodium citrate (vol/vol, 9:1) and centrifuged at 2000 × g for 10 min within 30 min since the draw. The supernatant was aliquoted and stored at −80 °C until further analysis. All measurements were performed by technicians who were blind to the origin of the samples.