Perioperative Fluid Management in Patients Receiving Major Abdominal Surgery - Effects of Normal Saline Versus an Acetate Buffered Balanced Infusion Solution on the Necessity of Catecholamines for Cardiocirculatory Support

Background Intraoperative hypotension is a common problem that significantly contributes to perioperative mortality and morbidity. At the moment the "gold standard" for perioperative fluid management is the so called "goal-directed therapy" that features fluid resuscitation followed if necessary catecholamines if needed for perioperative cardiocirculatory support. Worldwide the so called "physiological" sodium chlorid (0.9% NaCl) solution is the most often used infusate for perioperative fluid management. Despite its widespread use physiological saline has its major disadvantages such as the increased incidence of metabolic acidosis. Nevertheless catecholamines have their significant side effects as well (eg diminished renal perfusion, increased cardiovascular morbidity) and they therefore should be used with caution. In a prior study by group members on patients undergoing renal transplantation receiving either physiological saline or an acetate-buffered infusate showed a 50% decrease in catecholamine necessity in the acetate-buffered infusate group. The investigators therefore would like to evaluate the effects of the perioperative fluid choice on the necessity of catecholamine use. Aim * Evaluation of the perioperative fluid choice on the necessity of catecholamines for cardiocirculatory support. * Description of the relationship between perioperative fluid choice and minimal blood pressure as well as the time to catecholamine use and their dosage. Methods The investigators plan a prospective randomized-controlled trial of all patients undergoing major abdominal surgery at the Vienna General Hospital and Medical University of Vienna. Fluid management and catecholamine use will be based on a oesophageal Doppler -based treatment scheme.