Peritoneal dialysis (PD) catheter placement surgery for patients with end-stage renal disease (ESRD) can be performed under peripheral nerve block. This study assessed the ability of ultrasound guided left lateral transversus abdominis plane (TAP) block combined with rectus sheath (RS) block in PD catheter placement surgery. Also, surgeries are common surgeries performed in elderly patients throughout the world. Although there is an increasing trend towards laparoscopic surgeries, open procedures continue to remain common therapeutic modalities especially in the developing countries. Pain is reported more commonly in patients undergoing open procedures than laparoscopic procedures. Postoperative pain and tissue injury associated with surgery initiated a systemic stress response which has neuroendocrine, immunological, and haematological responses. Opioids are an important modality of postoperative pain management. They blunt the neuroendocrine stress response to pain. However, they are associated with several adverse effects like respiratory depression, nausea, vomiting , pruritus, constipation, urinary retension, bradycardia and hypotension. Transversus abdominis plane block（TAPB）is a relative novel procedure in which local anesthetic agents are injected into the anatomic plane between the internal oblique and the transversus abdominis muscle. It allows a significantly prolonged duration of analgesia during the early postoperative stage in abdominal surgery. This regional anesthesia technique provides analgesia to the skin, muscles of the anterior abdominal wall and parietal peritoneum in order to decrease the incision-related pain. Thus, it reduces postoperative opiate requirements and opioids-related side effects (nausea, vomiting, delayed resumption of intestinal transit, drowsiness, respiratory depression, urine retention). Nalbuphine, being mu antagonist an kappa agonist, has a ceiling effect in its respiratory depression. Many studies have reported that incidence of adverse effects like pruritus and PONV is lower with nalbuphine in comparison with morphine. The purpose of this study is to compare the analgesic efficacy and side effect profile of sulfentanyl with nalbuphine in elderly patients undergoing open gastrointestinal surgeries.

This study will be conducted in the department of Anesthesiology of the first affiliated hospital of Anhui Medical University, Hefei city, Anhui province, China. In our part 1, we are plan to observe 30 patients with ESRD who underwent PD catheter placement using left lateral transversus abdominis plane (TAP) block combined with rectus sheath (RS) block from our center. The TAP and RS blocks will be respectively conducted with 15 ml of 0.5% ropivacaine and 10 ml of 0.5% ropivacaine. Pain intensity will be evaluated by verbal rating scale (VRS), and the degree of patient and surgeon satisfaction will be qualified by a categorical scale. In part 2, the sample size was calculated based on the previous data in our hospital using sulfentanyl and flurbiprofen axetil as the opioid analgesic. The rate of postoperative nausea and vomiting(PONV) after surgery was 35%. Keeping the power of the study as 80% and 5% alpha error with the number of pairwise comparisons as 6, a total sample size of 124 was needed to identify a difference of 0.25 in the rate of PONV. Each group would require at least 31 patients. To allow for dropouts, the investigator decided to include 40 patients in each group. Elderly patients who were over 65 years old, undergoing open gastrointestinal surgeries were included in the study. Patients were divided into four groups, that is group S, group N1, group N2 and group N3, based on the drawing of an opaque sealed envelop.The anesthesiologists managing the intraoperative and postoperative courses as well as patients were blinded to the group which they belonged.The drug solution to be used intraoperatively and postoperatively as PCA (patient-controlled analgesia) was prepared by an assistant. Patients were interviewed before surgery and informed written consent was taken form each patient. Patients were shown a VAS (visual analogue score) of 0-10 for pain with 0 being no pain and 10 being worst pain ever felt, and instructed upon the use of PCA (patient-controlled analgesia) before surgery. Patients were subjected to monitoring of ECG, pulse oximetry and invasive blood pressure. 20ml combination of 0.5% ropivacaine and 10mg dexamethasone was injected bilaterally between the internal oblique and transverse abdominis muscles using sonography. All groups received standard general anesthesia.

Inclusion Criteria:

• Patients with ESRD scheduled for PD catheter placement belonging to American Society of Anesthesiologists (ASA) Grade 2 to 4 were included in the study.
• Elderly patients who were over 65 years old ,undergoing open gastrointestinal surgeries were included in the study.

Exclusion Criteria:

• Exclusion criteria included patients refusal, history of abdominal surgery, coagulation disorders, allergy to local anesthetic and localized infection on the injection site.
• The exclusion criteria were patient refusal, respiratory insufficiency,cardiac insufficiency,liver or kidney dysfunction，history of brain disease,local anesthetic allergy, dysfunction of blood coagulation，hemodynamic instability, history of any chronic pain, and history of chronic opioid use.