Is the Rectus Sheath block effective as the sole anesthetic technique for inserting a peritoneal catheter in patients with renal failure?

This is a prospective study. The study will include thirty consecutive patients or the available number of patients meeting the inclusion criteria within a period of 2 years. The subjects are patients with end-stage renal disease, according to The American Society of Anesthesiologists Physical Status Classification System (ASA) classified as II, III, or IV, who will undergo open surgery for the placement of a peritoneal catheter. The Bilateral Rectus Abdominis Sheath (RAS) block will be used as the sole anesthetic technique, administered under ultrasound guidance in a standardized manner. In our hospital, the Bilateral Rectus Abdominis Sheath (RAS) block technique is routinely employed for all patients undergoing peritoneal catheter insertion. Therefore, its use will not be exclusive to participants in this study. It will be performed by an experienced anesthesiologist (defined as having more than 10 years of clinical practice experience). To perform the RAS block, the patient is in the supine position and the ultrasound probe is positioned in a transverse orientation above the umbilicus, approximately 1 cm from the midline. The needle is inserted in-plane in a mediolateral direction through the subcutaneous tissue to penetrate the anterior sheath of the rectus abdominis muscle. The needle is then advanced through the muscle until its tip reaches the posterior sheath. After negative aspiration, the correct needle placement for the RAS block is confirmed by hydrodistension of the space between the flat abdominal muscle and the posterior sheath of the rectus under direct ultrasound guidance. The procedure will be performed bilaterally. For the RAS block, 2.0 mg/kg of 0.5% levobupivacaine will be used. 15 mL on each side, totaling 30 ml. .Before the surgery, the effectiveness of the block will be assessed with a cold sensation test and a pinprick pain test at the incision site. Immediately prior to the skin incision, patients will be sedated with remimidazolam to achieve a targeted Richmond Agitation Sedation Scale (RASS) score of -2 to -3, ensuring appropriate sedation for the regional anesthesia. Sufentanil (total of 10 mcg) will be administered to address anticipated discomfort from touching deep structures not covered by the block. Pain levels will be monitored using The Numeric Pain Rating Scale (NPRS) during the procedure, and if the NPRS score is 4 or higher, the patient will be converted to general anesthesia. A successful block will be indicated by not needing to switch to general anesthesia and no requirement for additional local anesthesia by the surgeon. Duration of the surgery is up to 1 hour. The recorded demographic data will include: age, sex, height, and weight. The recorded clinical data will include: ASA status, amount and dose of local anesthetic (LA), additional LA administered by the surgeon, conversion to general anesthesia, and NPRS scale immediately after the incision during the placement of the peritoneal catheter, and after the surgery at 1 and 6 hours after surgery, both at rest and during movement. Additionally, heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) will be recorded every 5 minutes, along with the need and dose of additional opioid analgesia, sedation level according to the RASS, and the need and dose of postoperative analgesia based on the NPRS. Also, every strategy used to assess adherence to the intervention will be recorded by the anesthesiologist. Complications arising from the block will also be recorded, including vascular puncture, damage to abdominal structures, hypotension, intravascular injection of LA or signs of local anesthetic systemic toxicity (LAST), and the percentage of failed blocks that required conversion to other types of anesthesia. Also, surgical complications will be recorded. At least once every month in a period of one year after the placement of the catheter, catheter function will be recorded, and complications like: catheter infection, primary and secondary peritonitis and mechanical complications (bleeding, "leak," catheter migration) will be noted.