Colloid Infusion for Optimal Outcomes In Non-cardiac Surgery (COIN Trial)

Post-induction hypotension occurs in 30-40% of patients undergoing surgery under general anesthesia. Perioperative hypotension is a significant independent risk factor for post-operative myocardial injury, acute kidney injury, stroke, and significantly increases 30-day mortality rate after surgery. Perioperative hypotension has been attributed to absolute or relative hypovolaemia secondary to pre-operative fasting and to the vasodilatory and negative inotropic effects of certain induction agents. Low baseline blood volume is a risk factor for post-induction hypotension. The general consensus remains that patients entering the operating room require fluids to make up for reduced pre-operative intake. Intravenous administration of 500 mL of crystalloid solution before induction of anaesthesia did not decrease the overall incidence of cardiovascular collapse during tracheal intubation of critically ill adults compared with no fluid bolus. Among patients in the intensive care unit requiring fluid challenges, intravenous crystalloid boluses of 250 ml before intubation did not reduce 90-day mortality. Preloading colloids reduced the occurrence of post-induction hypotension and vasopressor use, improved CI, and reduced SVV during the early intraoperative period. It is unknown whether pre-operative colloids infusion can reduce the incidence of post-operative complications by preventing post-induction hypotension. We will enroll patients with 18 years or older and undergoing elective surgery under general anesthsia. The participants in colloid group will receive intravenous colloids 5ml/kg before induction of anesthesia; who in crystalloid group will receive intravenous Ringer's solution 5ml/kg before induction of anesthesia. The primary outcome in this study is the incidence of post-operative complications (Clavien-Dindo) within 30 days. The secondary outcomes include the incidence of post-induction hypotension, the doses of vasopressors and inotropes intra-operatively, lengths of stay in hospital (LOS) post-operatively, optimal recovery post-operatively within 5 days.