The aim of this study is to assess the effect of oral melatonin versus intraoperative lidocaine infusion on incidence of postoperative delirium in elderly patients undergoing total hip arthroplasty under spinal anesthesia.
Elderly patients aged >65 years old undergoing unilateral total hip arthroplasty.
Patients with body mass index (BMI) (18-30) kg/m2.
American Society of Anesthesiologists (ASA) physical status I-III, scheduled to undergo unilateral total hip arthroplasty.
History of mental illness or scoring less than 8 using abbreviated mental test (AMT) before operation.
Obvious sinus bradycardia (heart rate of <50 beats per minute) or other serious cardiovascular diseases.
Symptomatic cerebrovascular disease (such as previous stroke).
History of liver and kidney dysfunction.