VTE Prophylaxis in a Bariatric Patient Undergoing Hip Replacement

Patient B-217 is a 55-year-old man admitted for elective total hip replacement. He presents with a 6-month history of worsening right hip pain due to osteoarthritis, which has limited his mobility. He has a body mass index of 42 kg/m², weight 130 kg, height 1.76 m. He is otherwise fit and well. He has a history of hypertension, treated with amlodipine 5 mg once daily. He has no known drug allergies. On examination, he is afebrile, blood pressure 142/88 mmHg, pulse 72 bpm, regular. Cardiorespiratory examination is unremarkable. His right hip has reduced range of motion, but no neurovascular deficit. Preoperative investigations: haemoglobin 14.5 g/dL, white cell count 6.5 × 10⁹/L, platelets 220 × 10⁹/L, serum creatinine 1.1 mg/dL (eGFR 75 mL/min/1.73 m²), serum potassium 4.2 mmol/L, ALT 30 U/L, INR 1.0. His medications are as above. He is scheduled for surgery tomorrow morning. The orthopaedic surgeon has asked you to prescribe appropriate venous thromboembolism prophylaxis, including drug, dose, timing relative to surgery, and any mechanical measures.