Preoperative Point of Care Ultrasound Guided Fluid Optimization and Intravenous Ondansetron to Prevent General Anesthesia-Induced Hypotension

Hypotension is a common side-effect of general anesthesia induction and is related to adverse outcomes including significantly increasing risk of one-year mortality. Even short durations of intraoperative hypotension have been associated with acute kidney injury (AKI) and myocardial injury.Half of all the patients were fluid-responsive, pointing to volume status as a significant risk factor. Ultrasound measurements of inferior vena cava (IVC) diameter with respiration, including the maximal diameter of the IVC (dIVCmax) at the end of expiration during spontaneous respiration and the collapsibility index (CI), have been recommended as rapid and noninvasive methods for estimating volume status. In attempt to prevent hypotension after spinal anesthesia induction, Ondansetron, a serotonin receptor antagonist, has been used effectively . Research Question Can preoperative IVC-US guided fluid optimization and intravenous ondansetron reduce the incidence of general anesthesia-induced hypotension in adult patients undergoing elective non-cardiac non-obstetric surgery?

Inclusion Criteria: 1. Age \> 18 2. Elective, non-cardiac, non-obstetric surgery under general anesthesia 3. American Society of Anesthesiologists physical status classification I - III Exclusion Criteria: 1. MAP below 60 mmhg prior to the induction of general anesthesia. 2. Patients treated with angiotensin converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB) on the day of surgery. 3. Patients with heart failure with ejection fraction (EF) \< 40%. 4. Patients with documented acute or chronic renal failure. 5. Patients with hepatic failure. 6. Patients with neuraxial (spinal/epidural) anesthesia performed before induction of general anesthesia. 7. Patients with suspected difficult airway. 8. Patients with documented allergy to Ondansetron or prolonged QT-syndrome. \-