The study aims to assess whether the transverse diameter of the right common femoral vein (RCFV) in the inguinal region could reflect the degree of post-spinal hypotension during elective orthopedic surgery.
Age > 60 years.
American Society of Anesthesiologists (ASA) physical state I-II.
Body mass index (BMI) ≤35 kg/m². Patients above this value will be excluded because obesity may cause technical difficulty and poor image quality in femoral vein ultrasound assessment.
Elective lower-limb orthopedic surgery under spinal anesthesia.
Patients refusing to participate.
History of psychiatric illness or seizures.
Absolute contraindications to spinal anesthesia: infection at the puncture site, severe coagulopathy/anticoagulation [defined as platelet count <75,000/µL, International Normalized Ratio (INR) >1.5, Activated Partial Thromboplastin Time (aPTT) >1.5 times control, or the use of anticoagulants such as warfarin, heparin, low molecular weight heparin, or direct oral anticoagulants within the recommended safety interval for neuraxial anesthesia], severe hypovolemia, increased intracranial pressure, or known allergy to local anesthetics.
Severe cardiac disease, including left ventricular ejection fraction <30%, Severe valvular heart disease (e.g., critical aortic stenosis), clinically significant arrhythmias (atrial fibrillation with uncontrolled ventricular rate >120 bpm, frequent ventricular ectopy or sustained ventricular tachyarrhythmia) and congestive heart failure such as New York Heart Association (NYHA) class III-IV.