Modified External Oblique Intercostal Plane Block Versus Erector Spinae Plane Block for Open Nephrectomy (EOIPB-ON)

Comparison of Modified External Oblique Intercostal Plane Block and Erector Spinae Plane Block for Postoperative Analgesia in Patients Undergoing Open Nephrectomy: A Prospective Randomized Controlled Trial

This prospective, randomized, assessor-blinded clinical trial aims to compare the postoperative analgesic efficacy of ultrasound-guided Erector Spinae Plane Block (ESPB) and Modified External Oblique Intercostal Plane Block (EOIPB) in patients undergoing elective open nephrectomy under general anesthesia. Sixty adult patients will be randomized to receive either ESPB or EOIPB before surgical incision. All participants will receive standardized general anesthesia and postoperative multimodal analgesia. Postoperative pain scores, opioid consumption, rescue analgesic requirements, and postoperative nausea and vomiting will be assessed during the first 24 hours after surgery. The study aims to determine whether one fascial plane block technique provides superior postoperative pain control and recovery following open nephrectomy.

Study Overview

• Status: Not yet recruiting
• Conditions: Postoperative Pain; Open Nephrectomy
• Intervention / Treatment: Procedure: Erector Spinae Plane Block; Procedure: Modified External Oblique Intercostal Plane Block

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Onur Baran, MD; Phone Number: +90 539 342 25 82; Email: dronurbaran@hotmail.com

Study Locations

• Turkey (Türkiye)
  • Tekirdağ
    • Tekirdağ, Tekirdağ, Turkey (Türkiye), 59000
      • Tekirdağ Namık Kemal University
      • Contact: Onur Baran, Associate Professor; Phone Number: +90 539 342 25 82; Email: dronurbaran@hotmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ESPB Group; Participants 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. Standardized general anesthesia and postoperative multimodal analgesia will be provided to all participants.	Procedure: Erector Spinae Plane Block; Ultrasound-guided erector spinae plane block performed after induction of general anesthesia using 30 mL of 0.25% bupivacaine before surgical incision.
Experimental: EOIPB Group; Participants will receive an ultrasound-guided modified external oblique intercostal plane block with 30 mL of 0.25% bupivacaine after induction of general anesthesia and before surgical incision. Standardized general anesthesia and postoperative multimodal analgesia will be provided to all participants.	Procedure: Modified External Oblique Intercostal Plane Block; Ultrasound-guided modified external oblique intercostal plane block performed after induction of general anesthesia using 30 mL of 0.25% bupivacaine before surgical incision.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain intensity at rest	Postoperative pain intensity will be assessed at rest using the 11-point Numeric Rating Scale, ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.	0, 2, 6, 12, and 24 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain intensity during movement	Postoperative pain intensity will be assessed during movement using the 11-point Numeric Rating Scale, ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate greater pain intensity.	0, 2, 6, 12, and 24 hours after surgery
Total Opioid Consumption	Total postoperative tramadol consumption recorded from patient-controlled analgesia during the first 24 postoperative hours.	24 hours after surgery
Rescue Analgesic Requirement	Number of patients requiring rescue analgesia during the first 24 postoperative hours.	24 hours after surgery
Postoperative Nausea and Vomiting	Incidence of postoperative nausea and vomiting during the first 24 postoperative hours.	24 hours after surgery
Heart Rate	Intraoperative heart rate measured in beats per minute at predefined intraoperative time points.	From induction of anesthesia until the end of surgery
Mean Arterial Pressure	Intraoperative mean arterial pressure measured in millimeters of mercury at predefined intraoperative time points.	From induction of anesthesia until the end of surgery

Collaborators and Investigators

• Sponsor: Namik Kemal University

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): February 1, 2027

Study Registration Dates

• First Submitted: June 22, 2026
• First Submitted That Met QC Criteria: July 21, 2026
• First Posted (Actual): July 24, 2026

Study Record Updates

• Last Update Posted (Actual): July 24, 2026
• Last Update Submitted That Met QC Criteria: July 21, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Regional Anesthesia; Pain Management; Postoperative Analgesia; Erector Spinae Plane Block; ESPB; Open Nephrectomy; Multimodal Analgesia; External Oblique Intercostal Plane Block; EOIPB
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Postoperative Complications; Pathologic Processes; Neurobehavioral Manifestations; Perceptual Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Agnosia
• Other Study ID Numbers: TNKU-EOIPB003

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data are not planned to be shared because no formal data-sharing infrastructure or approved data-sharing plan has been established for this study.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No