Modified External Oblique Intercostal Plane Block Versus Erector Spinae Plane Block for Open Nephrectomy

Open nephrectomy is associated with substantial postoperative pain that may impair recovery, delay mobilization, and increase opioid consumption. Regional anesthesia techniques have become important components of multimodal analgesia strategies aimed at improving postoperative outcomes while minimizing opioid-related adverse effects.

The erector spinae plane block (ESPB) and modified external oblique intercostal plane block (EOIPB) are ultrasound-guided fascial plane blocks that have demonstrated effectiveness in providing thoracoabdominal analgesia. However, evidence directly comparing these techniques in patients undergoing open nephrectomy remains limited.

This study is a prospective, randomized, controlled, assessor-blinded clinical trial conducted at a single tertiary academic center. Sixty patients aged 18 to 65 years with ASA physical status I-II who are scheduled for elective open nephrectomy will be enrolled and randomized in a 1:1 ratio to one of two study groups.

Participants assigned to the ESPB group will receive an ultrasound-guided erector spinae plane block with 30 mL of 0.25% bupivacaine after induction of general anesthesia and before surgical incision. Participants assigned to the EOIPB group will receive an ultrasound-guided modified external oblique intercostal plane block using the same volume and concentration of local anesthetic.

All patients will receive standardized general anesthesia, postoperative intravenous patient-controlled analgesia with tramadol, scheduled paracetamol, and rescue analgesics according to institutional protocols. Patients will be followed in the post-anesthesia care unit and at postoperative 2, 6, 12, and 24 hours.

The primary objective is to compare postoperative pain intensity between the two groups during the first 24 postoperative hours. Secondary objectives include comparison of opioid consumption, rescue analgesic requirements, postoperative nausea and vomiting, and perioperative hemodynamic parameters.

The results of this study may help identify the optimal regional analgesia technique for patients undergoing open nephrectomy and contribute to enhanced postoperative recovery.

Inclusion criteria

• Age between 18 and 65 years.
• American Society of Anesthesiologists (ASA) physical status I or II.
• Scheduled for elective open nephrectomy.
• Able and willing to provide written informed consent.
• Willing to comply with study procedures.

Exclusion criteria

• Refusal to participate or inability to provide informed consent.
• Emergency surgery.
• Body mass index (BMI) greater than 35 kg/m².
• Known allergy or hypersensitivity to local anesthetics.
• Infection at the planned block insertion site.
• Coagulopathy or ongoing anticoagulant therapy.
• Pregnancy or breastfeeding.
• Prisoners or other vulnerable populations unable to provide independent consent.