The effect of an intraoperative, goal-directed volume protocol in abdominal surgery within an accelerated recovery program after surgery (Enhanced Recovery Program After Surgery: ERAS-Program)

INTERVENTION: Targeted‐volume application guided by esophageal doppler vs conventional volume application CONDITION: Colonic resection above the peritoneal reflection ; Digestive System ; Colonic resection above the peritoneal reflection PRIMARY OUTCOME: Difference in the amount of intravenously administered crystalloid and colloid fluid on the day of operation SECONDARY OUTCOME: 1. Reduction of the intraoperative requirement for vasoactive drugs ; 2. Time to hospital discharge ; 3. Rate of postoperative complications (pain, delirium. infections, cardiac, pulmonary, gastrointestinal and renal dysfunction). Patients will be monitored until they fulfill the hospital discharge criteria or up to 30th postoperative day. INCLUSION CRITERIA: 1. Written patient consent 2. Patients who undergo colonic resection above the peritoneal reflection 3. Patients who are treated within the context of an accelerated post‐operative recovery program