Comparison of the Effects of Gelatine (Gelofusine ® B. Braun) Versus Crystalloid Solution (Ringerfundin ® B. Braun) for Volume Therapy on Coagulation, Thrombocyte Function and Thrombelastometry (ROTEM ®), in Elective Hip Replacement Surgery

After obtaining the research ethics committee approval, 50 patients, undergoing elective surgery for hip replacement will be included. The informed consent must be signed prior to randomization. After arriving to the operation theatre, the patients informed consent and inclusion and exclusion criteria will be reviewed. Afterwards, the patients will be randomized in one of two groups. Prior to the anaesthesia induction, blood for the thrombocyte function test, coagulation tests and thrombelastometry wil be drawn via a metal cannula. A large bore peripheral venous cannula (G18 or more) will be introduced. In case of a ASA status of III and higher based on cardiovascular morbidity an arterial catheter via the radial artery for invasive blood pressure monitoring will be introduced. Urinary catheter will be introduced to monitor intraoperative diuresis. A continuous crystalloid infusion n a dose of 5 ml/kg/hour will be administered for basal fluid substitution. The volume replacement using blinded gelatine/crystalloid solution will be performed via fluid challenge (repeated 250 ml fluid boluses during a 5 minute interval) to hemodynamic targets (increase in blood pressure, decrease in heart rate), in case of a decrease of MAP to 65 mm Hg (16) or to 70 mmHg in preexisting hypertension. The hemodynamic variables before and after fluid challenge will be exactly recorded. In case the patient hemodynamics does dot respond to a fluid challenge, or in case of a drop of blood pressure to less than 55 mmHg, a bolus of 5-10 mg of ephedrine (repeatedly) will be administered. Further recorded variables will be: blood loss (suctioning, sponges), diuresis, number of transfusions administered. Repetitive hemoglobin concentration tests using the HemoCue 201+ device will be performed and an intraoperative blood transfusion trigger of 90 g/l of hemoglobin concentration will be used, 100 g/l in case of a patient with chronic cardiovascular or respiratory disease (5). After reaching the blood loss of 1000 ml, blood samples will be drawn for laboratory hemoglobin concentration and coagulation testing. The trigger for platelet transfusion will be a thrombocyte count of less than 50000 x 109, or sings of platelet dysfunction on thrombelastometry. Tranexamic acid will be administered in case of signs of fibrinolysis on thrombelastometry or in case of life threatening bleeding. At the end of surgery, a second blood sample for platelet function test, thrombelastometry, full blood count and standard coagulation tests will be drawn. The amount of blinded study infusion, continuous crystalloid solution, transfusions and ephedrine administered, diuresis and blood loss will be recorded. Blood urea and creatinine, diuresis, coagulations and full blood count will be recorded postoperatively. Hospital and ICU length of stay, hospital and 90-day mortality will be followed.