The Effectiveness of External Oblique Intercostal Plane Block in the Management of Acute Pain Following NephrectomyNephrectomy is a commonly performed surgical procedure in urology due to benign or malignant reasons. Depending on the underlying pathology and the patient, the surgical procedure can vary in scale, including simple nephrectomy, partial nephrectomy, and radical nephrectomy, and may be performed either openly or laparoscopically. Postoperative pain can prolong the patient's hospital stay and impair comfort. Due to pain, patients may develop atelectasis and hypertension after surgery, leading to an increased need for narcotic analgesia. The increased demand for narcotic analgesics according to patients' age and characteristics can affect renal functions and may not improve patient comfort due to nausea and vomiting. Regional anesthesia of the torso and abdominal wall has generally focused on epidural analgesia. However, the increased use of minimally invasive laparoscopic techniques, the significance of postoperative anticoagulation regimens, and early ambulation have led to changes in analgesia selection. Although transversus abdominis plane blocks and rectus sheath blocks are frequently applied, their inability to adequately manage abdominal pain alone, along with the challenges posed in obese patients, has led to a recent shift towards the external oblique intercostal plane block.The application of the EOIP block involves the patient being in a supine position, with either the clavicle or mid-axillary line palpated to locate the 6th rib. An ultrasound probe is placed 1-2 cm lateral to the midclavicular line over the 6th rib. Under aseptic conditions, a 22-gauge 25-50 mm block needle is advanced to the 6th rib using the in-plane technique. Two ml of saline is injected for hydrodissection to ensure accurate placement. Avoiding subperiosteal injection, hydrodissection is performed between the external oblique muscle and the 6th rib. Subsequently, 20-30 ml of 0.25% bupivacaine is injected into this area. The block is then repeated on the other side.

In our clinic, a multimodal analgesia approach is preferred for patients undergoing nephrectomy. Plan blocks (administered to every suitable and consenting patient) are used in conjunction with intravenous analgesic agents. Blocks are routinely applied to patients undergoing nephrectomy, who are monitored in the postoperative intensive care unit. Our study will include suitable patients who have undergone nephrectomy and received this block. The anesthesiologist managing anesthesia will be different from the anesthetist monitoring pain. Our study is entirely observational, and no randomization will be conducted. There will be no intervention in either analgesia or anesthesia management. Patients who consent to participate will be included in the study in the recovery room after the block is administered.

The aims of the study are as follows:To examine postoperative opioid consumption.To assess the effectiveness of external oblique intercostal plane block in managing postoperative pain in nephrectomy patients.To evaluate pain at postoperative hours 0, 2, 4, 6, 12, and 24 using the Numerical Rating Scale (NRS).To assess pain increase with movement and effort at postoperative hours 0, 2, 4, 6, 12, and 24 using NRS.