Postoperative pain management has an important place in anesthesia practices. In order to ensure patient comfort after the surgery, to start postoperative rehabilitation early, and to prevent the process from causing mood disorders such as anxiety and pathological conditions such as chronic pain syndrome, the pain caused by the operation in the postoperative period must be effectively relieved. Pericapsular nerve group (PENG) block; It is a regional anesthesia technique that targets the anterior capsule of the hip joint and aims to block the joint branches of the accessory obturator nerve and femoral nerve by administering local anesthetic. Although it has been described recently, controlled prospective studies in the literature have shown it to be a safe and effective regional technique for postoperative pain after hip surgery. However, volume studies on this block are limited.

Therefore, in this study, we aimed to determine the optimal dose by comparing the effectiveness of PENG block on pain using different local anesthetic volumes

It was planned to be performed with patients who had hip replacement surgery and patients who are included in the study after obtaining the necessary consents will be randomly assigned to one of Group I or Group II by sealed envelope method. Patients taken to the operating room will receive standard monitoring such as ECG, peripheral oxygen saturation and noninvasive blood pressure monitoring. Midazolam 1 mg IV, fentanyl 1 mcg/kg IV, propofol 1.5-2 mg/kg IV and rocuronium 0.6 mg/kg IV. After routine anesthesia induction, the patient will be intubated with the appropriate intubation tube. Anesthesia maintenance will be provided with 0.8 MAC sevoflurane and remifentanil infusion, as we apply in our routine. Ventilator parameters will be regulated as FiO2 50%, Vt: 0.8 ml/kg, and respiratory frequency 10-14/min, so that EtCO2 is in the range of 25-40 mmHg. Near the end of the operation, our routine analgesic application is 0.1mg/kg IV Morphine will be administered. After the operation is completed, the pericapsular nerve group block will be performed by entering the patient's suprainguinal area with a 100 mm block needle under ultrasound guidance, as in the standard practice of our clinic, and local anesthetic will be administered to the area between the psoas muscle tendon and the hip joint. During the procedure, ultrasound will be used to determine the location and visualize the distribution of the administered drug. The administered drug volume was planned to be 20 cc of 0.25% bupivacaine for group I patients and 10cc of 0.25% bupivacaine for group II patients (their concentrations would be the same but their volumes would be different). Then, the patient will be awakened from anesthesia; Patients with adequate respiratory effort below sevoflurane 0.2 MAC should receive atropine 0.1 mg/kg and neostigmine 0.05 mg/kg IV, which we routinely use, will be applied and extubated. Postoperative 30th minute, 4th hour, 6th hour, 12th hour, 24th hour pain intensities of the patients were evaluated using NRS (Numerical rating Scale) score (0-10) and postoperative Nausea and Vomiting Descriptive Scale (0 = none, 1 = mild nausea, 2 = nausea, 3 = vomiting once, 4 = vomiting more than once) will be evaluated and recorded. At the end of the surgery, patients will be given IV Morphine PCA (patient controlled analgesia) with a 2 ml bolus at a concentration of 0.5 mg/cc for 15 minutes and the amount of Morphine used during the hours when the patient's NRS score is recorded will be recorded. The patients' mobilization time after the operation will be recorded. 0.15 mg/kg IV Ondansetron will be administered for patients with Postoperative Nausea and Vomiting Descriptive Scale 2 and above. 24 hours after the surgery, patient satisfaction will be evaluated and recorded on a Likert Satisfaction scale (1-5).