Hypotension Prediction Index and Intraoperative Hypotension Incidence

Inclusion Criteria: * Age\> 60 years old * Frail score \> 2 * ASA≥2 * Planned to receive general anesthesia * Elective laparoscopic or laparotomy major abdominal surgery with an expected duration of \> 180 minutes * Planned to receive an arterial line monitoring intraoperatively * Being able to give written informed consent prior to surgery Exclusion Criteria: * Severe cardiac arrhythmia including atrial fibrillation * Severe aortic stenosis * Uncontrolled Hypertension (sitting systolic blood pressure ≥ 160 mmHg and/or diastolic blood pressure ≥100 mmHg during screening) * Significant hypotension before surgery defined as a MAP \<65mmHg * Chronic kidney disease with glomerular filtration rate \<30 ml/min/1.73 m2 or requiring renal-replacement therapy for end-stage renal disease * Organ transplant surgery, surgery involving the kidney, liver surgery requiring hilar blockage, surgery requiring controlled hypotension or controlled low central venous pressure