Objectives:~The purpose of the study is to conduct a randomized intervention cohort study using pre-operative fluid therapy to assess its effect on blood pressure during the post-induction period. The investigators are testing the hypothesis that preoperative Crystalloid bolus decreases the risk of post-induction hypotension, specifically the time-weighted average (TWA) mean arterial pressure (MAP) under 65 mmHg during the first 20 minutes after anaesthetic induction or until surgical incision, whichever is first, compared to standard of care, which is minimal fluid administration in the pre-operative period.~Methods:~The investigators will conduct a randomized intervention cohort study using pre-operative fluid therapy to assess its effect on blood pressure during the post-induction period. The intervention group will receive a balanced crystalloid solution bolus within 20 to 40 minutes before induction of anaesthesia. The control group will be treated according to the current clinical standard of care. The investigators will compare the time-weighted average (TWA) mean arterial pressure (MAP) under 65 mmHg during the first 20 minutes after anaesthetic induction or until surgical incision (whichever comes first).
Theoretical framework:~Hypotension during surgery directly impacts patients' postoperative outcomes and complications. Decrease in blood pressure measurements secondary to anesthetic drugs is an expected scenario in most surgical cases. Moreover, hypovolemia secondary to fast pre-operative period may facilitate post-induction hypotension which can be compensated by fluid bolus pre-operatively.