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.

Spinal anesthesia is commonly used in orthopedic procedures but often results in hypotension, particularly in elderly patients due to reduced cardiovascular reserve and impaired autonomic function.

Ultrasound measurement of the right common femoral vein (RCFV) diameter has recently been proposed as a simple, non-invasive marker of intravascular volume status and a potential predictor of spinal anesthesia induced hypotension. To date, most evidence comes from obstetric populations undergoing cesarean delivery, limiting its applicability in other high-risk groups.

Inclusion Criteria:

• 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.

Exclusion Criteria:

• 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.
• Severe uncontrolled hypertension, defined as persistent mean arterial pressure (MAP) ≥120 mmHg or systolic blood pressure (SBP) ≥180 mmHg and/or diastolic blood pressure (DBP) ≥110 mmHg despite medical therapy.
• Severe respiratory diseases (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage III-IV chronic obstructive pulmonary disease, or forced vital capacity (FVC) <50% predicted).
• Baseline bradycardia (<50) or mean arterial blood pressure less than 60mmHg.
• Emergency surgeries.

The prospective observational study will be conducted in orthopedic theatre in Cairo University Hospitals.

The data will be available upon a reasonable request from the corresponding author after the end of study for one year.

After the end of study for one year.

The data will be available upon a reasonable request from the corresponding author.