Effect of Bilateral RSB on Postoperative Delirium in Elderly Patients Undergoing Laparoendoscopic Single-site Surgery

1. Study design and setting 320 elderly patients undergoing LESS surgery under general anesthesia (including inguinal hernia and cholecystolithiasis), gender, aged 65-80 years, American Society of Anesthesiologists (ASA) physical status I-II. Exclusion criteria: MMSE of 1 day before surgery \< 27, communication and dysfunction (e.g., vision, hearing), cerebrovascular history, local anesthetic allergy, opioid allergy, puncture site infection, abnormal clotting. 2. Subjects Patients were allocated randomly to R group (bilateral rectus abdominis sheath blocks combined with the general anesthesia group) and G group (the simple general anesthesia group) according to computer-generated random number table. All patients and an investigator who was responsible for follow-up during 48 postoperative hours were blinded to the randomization groups. In addition, during preoperative visits, the investigators instructed patients how to use the patient-controlled intravenous analgesia (PCA) device for pain management, as well as how to use the visual analog scale to evaluate pain at rest and while coughing. All the bispectral index (BIS) value in the present study was maintained between 40 and 60 during surgery. All patients voluntarily signed informed consent. 3. General anesthesia Patients were monitored by electrocardiogram, pulse oximetry and non-invasive blood pressure (one measurement every 3 min) while entering operation room. A radial artery catheter was also placed for invasive arterial pressure and blood gas monitoring. The induction of general anaesthesia was performed intravenously with sufentanil 0.5 µg/kg, propofol 1-2 mg/kg, and rocuronium 0.6 mg/kg. Endotracheal intubation was performed with a double-lumen tube. Sevoflurane was wsed at a minimal alveolar concentration (MAC) of 0.8-1, remifentanil and propofol were used for the maintenance. Fluid management was at the discretion of the attending anaesthesiologist.