A Randomized Study of Goal-directed Therapy in the Elderly High-risk Patients Undergoing Total Hip Replacement

After sedated with IV 0.02 mg/kg midazolam, all patients will receive arterial, central venous, and L3-4 intrathecal catheterizations. A T12 sensory level block was attained with ropivacaine through the intrathecal catheter. Besides currently recommended monitoring during the intraoperative period, arterial blood pressure, stroke volume (Edwards Lifesciences, Irvine, Calif.), and central venous oxygen saturation (Edwards Lifesciences) will be measured and recorded. All Patients will receive intranasal oxygen 2 mL/min and be kept normothermic (body temperature > 36°C). Patients in both groups receive 8 mL/kg/hour of Ringer's lactate solution from 30 minutes prior to induction of anaesthesia through the end of surgery, when the rate will be decreased to 100 mL/hour. In addition, boluses of colloid will be given to different protocol group according to the study arm to which the patient allocated.Postoperative care and discharge criteria were predefined using the hospital care map and protocol.