Background
delirium, bradycardia, fractures, respiratory depression, femoral head necrosis
RESPIRATORY DEPRESSION, DISEASES
Hip fractures and femoral head necrosis are projected to become more common as the ageing population increases. Hip replacement, including partial and total hip arthroplasty, is a major surgical technique for these kinds of diseases [Dexmedetomidine, a highly selective α2-adrenoreceptor agonist, is widely used in clinical practice for its unique characteristics, such as antianxiety and arousable sedation with minimal respiratory depression during operation or ICU stay [Midazolam is a benzodiazepine commonly used as sedative medications for surgery and general anaesthesia. It is often used in elderly patients undergoing low risk procedures due to the benefits of rapid onset, anxiolysis and haemodynamic stability compared to other sedatives. However, current anaesthetic guidelines advise the avoidance of benzodiazepines in elderly patients due to concerns of an increased risk of delirium [However, the influence of dexmedetomidine on haemodynamics should not be ignored. It has been shown that dexmedetomidine generally increases the incidence of bradycardia [In this study, different initial doses of dexmedetomidine were used in general anaesthesia for elderly patients who underwent hip replacement to evaluate its influence on perioperative haemodynamics and postoperative recovery quality after intravenous anaesthesia combined with sevoflurane. Through the results of this study, we expected to determine the appropriate dose range of dexmedetomidine to provide satisfactory sedation and analgesia in elderly patients with stable haemodynamics during the perioperative period of hip replacement under general anaesthesia.