PAI-1 and t-PA/PAI-1 Complex Potential Markers of Fibrinolytic Bleeding After Cardiac Surgery Employing Cardiopulmonary Bypass

Agnese Ozolina; Eva Strike; Inta Jaunalksne; Angelika Krumina; Lars J Bjertnaes; Indulis Vanags

Disclosures

BMC Anesthesiol. 2012;12(27) 

In This Article

Methods

The study protocol and the informed consent form were approved by the Ethics Committee (No.151209–4L) of Pauls Stradins Clinical University Hospital, Riga, Latvia. Written informed consent was obtained from every patient.

Population

Between 1 May and 30 December 2010, 88 consecutive adult patients, who were admitted to the hospital to undergo cardiac surgery by the use of CPB, were considered for a prospective observational study. None of the patients received antifibrinolytic medicines during - or after the surgery.

Inclusion and Exclusion Criteria

Inclusion criteria: > 18 years of age, first-time coronary artery bypass grafting (CABG) and/or valve replacement under CPB, EuroSCORE[14] < 10%, coagulation tests within normal ranges at baseline {prothrombin time (PT) 70–120%} or international normalized ratio (INR) 0.8–1.2, fibrinogen plasma concentration 1.5 – 3.5 g/L, platelet count (PLT) 150 – 400 × 109/L, hemoglobin (Hb) concentration > 135 g/L for men and > 120 g/L for women) and no anticoagulant, - anti-aggregating or non-steroidal anti-inflammatory drugs for, at least, five days prior to surgery in order to disclose drug-induced platelet dysfunction. The last dose of low-molecular-weight heparin (LMWH) was administered the evening before the surgery. Exclusion criteria: emergency - and redo operations, preoperative hemostatic disorders with a history of hemorrhagic events or coagulopathy (PT below 50% or INR greater than 1.5, fibrinogen plasma concentration below 1.5 g/L, PLT lower than 100 × 109/L) and severe renal and/or hepatic dysfunctions.

Perioperative Management

Anesthesia was induced with fentanyl (Fentanyl-Kalceks® 0.05 mg/ml, A/S Kalceks, Latvia), 0.2–0.3 mg, midazolam (Dormicum®, F. Hoffman-La Roche AG, Switzerland), 2.5–5 mg, propofol (Propofol-Lipuro® 10mg/ml, B. Braun Melsungen AG, Germany) 1–3 mg/kg and cisatracurium (Nimbex® 2 mg/ml, GlaxoSmithKline Manufacturig S.p.A, Italy) 0.2 mg/kg intravenously and maintained with inhalation of sevoflurane (Sevoflurane Piramal®, Piramal Healthcare Ltd, United Kingdom) at 0.8–1.2 MAC. Before the start of CPB, heparin (Pan-Heparin Sodium®, Panpharma S.A./Rotexmedica Gmbh, Germany) was administered at a dose of 300–400 units/kg followed by 5.000 - 10.000 units to maintain an activated coagulation time (ACT) above 480 seconds. During CPB (Admiral®, Eurosets TM, Italy), anesthesia was maintained with fentanyl 0.03–0.06 mkg/kg/min, propofol 3–5 mg/kg/h and cisatracurium 0.1 mg/kg/h. Patients were cooled to a bladder temperature of 34–35°C. Myocardial protection was achieved by using St. Thomas 4:1 cardioplegia (AlleMan®, Germany). Weaning off CPB after the surgery was performed after the patient was rewarmed to a bladder temperature above 36°C. After separation from CPB, protamine (Protamin Meda®, Meda Pharma, Austria) was administered at a dose of 1 mg per 100 units of heparin followed by additional doses until ACT had returned to baseline. Postoperatively, standard unfractionated heparin was administered from 20–24 hours after valve surgery. Warfarin (Orfarin®, Orion Pharma, Finland) treatment was resumed on the third postoperative day if the patient had no signs of bleeding or need for re-operation. LMWH (Fragmin® 2500 IU/1ml, Pfizer, Belgium) was also started 20–24 hours after CABG in patients without increased bleeding tendency. According to our clinical guidelines, a hematocrit < 26% indicated requirement for transfusion of packed erythrocytes; PT < 50%, and PLT < 90 × 109/l indicated need for transfusion of freshly frozen plasma and platelet concentrates, respectively. In conditions of increased bleeding with drop in fibrinogen, cryoprecipitate was given.

Demographic and Laboratory Data

We noticed the following demographic and perioperative variables: age, sex, body mass index (BMI), ejection fraction (EF), comorbidities, preoperative anticoagulation therapy, type of surgery, extracorporeal circulation time (min), aortic clamp - and reperfusion times, and transfusion requirements. Moreover, we analyzed PAI-1 preoperatively and t-PA/PAI-1 complex 24 hours postoperatively. PAI-1 (normal range 1–25 ng/ml) and t-PA/PAI-1 complex (normally < 5 ng/ml) were determined by using enzyme-linked immunosorbent assay (ZYMUTEST, HYPHEN BioMed, France). Cross-linked fibrin degradation products (D-dimer, normally < 300 ng/ml) were quantified with the immunoturbidimetric test (D-dimer PLUS, Dade Behring, Marburg, Germany). Fibrinogen plasma concentration was determined according to Clauss.[15] PT was analyzed with a prothrombin complex assay (Lyophilized Dade® and Innovin®, Siemens Healthcare Diagnostics, USA). All the coagulation tests were determined using Sysmex® CA-1500 (Siemens Healthcare Diagnostics, Germany). Hb and PLT were analyzed by means of a Beckman Coulter LH 750 Hematology Analyzer.

Groups of Patients

Bleeding volume was recorded as milliliters of chest tube drainage (CTD) 24 hours (h) postoperatively and the patients were allocated to two groups; Group I: bleeding arbitrarily defined as CTD > 500 ml/24h and Group II with CTD ≤ 500 ml/24h. Indication for reoperation because of suspected surgical bleeding was based on evaluation of clinical and hemodynamic changes. If the patient was re-operated, the CTD volume until reoperation, and 24 hours afterwards was registered. A surgical bleeding was diagnosed only if one or more specific bleeding sites were identified. Then, the patient was excluded from further study. If no specific site was located, the bleeding was registered as hemostatic disorder and the patient was allocated to the most appropriate group according to the bleeding volume. Plasma fibrinogen, PT, PLT and Hb were assessed preoperatively (T0) and together with D-dimer upon admission to the intensive care unit (T1), and at 6 and 24 hours (T6, T24) postoperatively.

Statistical Analysis

Data was analyzed with SPSS (SPSS® version 17.0, Chicago, IL). Continuous variables were presented as mean ± standard deviation (SD) and categorical variables as percentages (%). Linear regression (Pearson's correlation coefficient) was used to analyze the relationships between the demographic and the surgical data and the hematologic -, coagulation – and fibrinolysis parameters (PAI-1, t-PA/PAI-1 complex and D-dimer) and bleeding volumes, respectively. Comparisons between the groups were performed with Mann–Whitney U test for non-parametric variables, and two-sample t test or ANOVA for parametric variables. Chi-square test was used to analyze categorical data. Statistical significance was defined as a P< 0.05.

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