Effect of Oral Melatonin Versus Intraoperative Lidocaine Infusion on Incidence of Postoperative Delirium in Elderly Patients Undergoing Total Hip Arthroplasty

Patients will receive one capsule of melatonin (5mg) orally the night before surgery at 9 pm, the night of the operation, and two nights after the surgical operation at 9 pm, also the patients will receive 10 ml bolus of saline intravenous (IV) over 10 min before induction of anesthesia, then continuous infusion of saline (20 ml/hr) until the end of surgery.

Patients will receive a bolus (10 ml) of intravenous lidocaine (1mg/kg) diluted with saline over 10 min before induction of anesthesia. Continuous infusion of 1.5 mg/kg/hr of intravenous lidocaine diluted with saline (20 ml/hr) will be administered until the end of the surgery, also will receive placebo capsule the night before surgery at 9 pm, the night of operation and two nights after the surgical operation at 9 pm.

Patients will receive a bolus (10 ml) of saline over 10 min before induction of anesthesia, then continuous infusion of saline (20 ml/hr) and placebo capsule the night before surgery at 9 pm, the night of the operation and two nights after the surgical operation at 9 pm.