Internal Jugular Vein Ultrasound and Acute Kidney Injury After Abdominal Surgery

This observational study aims to learn whether changes in the internal jugular vein during anesthesia induction can help predict low blood pressure and kidney injury after surgery. The main questions it aims to answer are: 1. Can the internal jugular vein collapsibility index before anesthesia predict low blood pressure during induction? 2. Can the change in internal jugular vein collapsibility from before to just after anesthesia predict low blood pressure during surgery and acute kidney injury after surgery? Participants will have routine ultrasound scans of the neck before anesthesia and again shortly after they fall asleep for surgery. Researchers will also record blood pressure during surgery and measure kidney function after surgery using routine blood tests. and again shortly after they fall asleep for surgery. Researchers will also record blood pressure during surgery and measure kidney function after surgery using routine blood tests.

Inclusion Criteria: * Elective or Urgent (Non-emergent) major abdominal/ visceral surgery under general anesthesia * General anesthesia with propofol induction (TCI/ manual) * Expected surgical duration \> 60 minutes * Continous BP monitoring (Invasive arterial line or non-invasive cuff at 2 minute recording intervals) * Serum creatinine and eGFR (CKD-EPI) available within 30 days prior to surgery * Written informed consent obtained before surgery * Patient accessible by phone 30 days postoperatively Exclusion Criteria: * Emergency surgery (immediate life-saving, consent unobtainable) * End-stage renal disease (eGFR \< 15 mL/min/1.73 m²) or dialysis-dependent * Concomitant cardiac surgery or carotid endarterectomy * Liver transplantation * Known Internal Jugular Vein/ Inferior Vena Cava thrombosis or Superior Vena Cava syndrome * Any anatomical neck abnormalities precluding Internal jugular vein ultrasound * Induction with ketamine or etomidate as sole Induction agent * Neuraxial anesthesia (spinal or epidural) before propofol induction * Active decompensated heart failure (NYHA IV or acute pulmonary edema at time of Surgery) * Same-admission reoperation within 30-day study window * Withdrawal of consent at any point