Dexmedetomidine Combined With Ropivacaine for Postoperative Continuous Femoral Nerve Block

Exclusion Criteria

• •Refuse to participate in this study;
• •Preoperative history of schizophrenia, epilepsy, Parkinsonism, or myasthenia gravis;
• •Inability to communicate in the preoperative period because of coma, profound dementia or language barrier;
• •Preoperative hemorrhagic disease or coagulopathy (platelet count, prothrombin time and/or activated partial thrombin time below the lower limit of normal);
• •Preoperative obstructive sleep apnea (diagnosed as obstructive sleep apnea, or STOP-Bang score ≥3);
• •Preoperative sick sinus syndrome, severe sinus bradycardia (\< 50 beats per minute), or second-degree or above atrioventricular block without pacemaker;
• •Severe hepatic dysfunction (Child-Pugh class C);
• •Severe renal dysfunction (requirement of renal replacement therapy before surgery);
• •ASA classification ≥ IV or unlikely to survive for more than 24 hours after surgery.