RISS Versus Lower Thoracic ESP Block for Analgesia After Laparoscopic Abdominal Surgery: A Randomized Trial

Analgesic Efficacy of Ultrasound-Guided Rhomboid Intercostal and Subserratus (RISS) Block Versus Lower Thoracic Erector Spinae Plane Block (ESPB) After Abdominal Laparoscopic Surgery

The goal of this clinical trial is to investigate the analgesic efficacy of ultrasound-guided Romboid Intercostal and Subserratus (RISS) block versus lower thoracic Erector Spinae Plane (ESP) block after laparoscopic abdominal surgery. The main questions it aims to answer are:

Does ultrasound-guided Romboid Intercostal and Subserratus (RISS) block is effective as the lower thoracic Erector Spinae Plane (ESP) block for intra and postoperative analgesia after laparoscopic abdominal surgery for the first 24 hours? What complications do participants have when doing these interventions?

Researchers will compare the analgesic efficacy of ultrasound-guided Romboid Intercostal and Subserratus (RISS) block with the lower thoracic Erector Spinae Plane (ESP) block after laparoscopic abdominal surgery.

Participants will:

Start general anesthesia and be given either block according to the randomization chart.

The blood pressure and heart rate will be measured at intervals to determine if the participants need extra intraoperative analgesics.

Numerical Rating Scale (NRS) will be used postoperatively to test pain severity.

Rescue morphine analgesia will be measured and compared in both groups.

Any complications will be reported.

Patient and surgeon satisfaction will be measured.

Study Overview

• Status: Not yet recruiting
• Conditions: Pain After Surgery
• Intervention / Treatment: Procedure: Group A (n=35): Ultrasound-guided RISS block (RISS):; Procedure: Group B (n=35): Ultrasound-guided lower thoracic ESP block

Detailed Description

The aim of this study is to investigate the analgesic efficacy of ultrasound-guided Romboid Intercostal and Subserratus (RISS) block versus lower thoracic Erector Spinae Plane (ESP) block after laparoscopic abdominal surgery.

Hypothesis

This study hypothesize that both RISS and ESP blocks relieve somatic pain equally, but ESP block relieves visceral pain better than RISS block, thereby reducing opioid consumption and improving patient satisfaction.

Methodology using:

I. Study design

Double-blinded randomized clinical trial study.

II. Study setting and location The study will be conducted at the operative theater of Souad Kafafi University Hospital (SKUH), Misr University for Science and Technology (MUST).

III. Study population:

Patients aged from 18 to 60 years old scheduled for laparoscopic abdominal surgery will be randomized in a 1:1 ratio after induction of general anesthesia, either:

Group A: Receiving ultrasound-guided RISS block. A solution composed of 20 ml mixed xylocaine 1% + 0.25% bupivacaine + 4 mg dexamethasone on each side.

Group B: Receiving ultrasound-guided lower thoracic ESP block (T8-T9) A solution composed of 20 ml mixed xylocaine 1% + 0.25 % bupivacaine + 4 mg dexamethasone on each side.

The infiltrative local anesthesia will be administered via a 22-gauge, 80-mm Echogenic block needle.

Postoperative analgesia:

The participants in both groups will receive analgesia in accordance with the following protocol:

• Pain will be assessed using a Numerical Rating Scale (NRS) 0-10.

  1. Mild pain (NRS 1-3) will be treated with 1 g paracetamol IV every six hours (maximum 4 g/day).
  2. Moderate pain (NRS 4-6) will receive the same paracetamol regimen plus ketorolac 30 mg IV every eight hours (maximum 120 mg/day).

  3. Severe pain (NRS 7-10) will receive the above plus 0.1 mg/kg IV morphine when indicated.

     Study outcomes:

     Primary Outcome Measure:

• Efficacy of postoperative analgesia for first 24 hours.

Secondary Outcome Measures:

• Total morphine equivalent consumption (mg) in 24 h.
• Surgeon satisfaction (ability to perform active movements, 1-5 scale).
• Patient satisfaction (1-5 scale).
• Onset time of analgesia (min).
• Duration of postoperative analgesia (time to first rescue).
• Pain intensity via NRS at 2, 6, 12, 18, and 24 h.
• Intraoperative vital signs (HR, NIBP).
• Possible complications (pneumothorax, LAST, and vascular puncture) intra- and post-operatively.

Sample size calculation The sample size calculation was performed using G. power 3.1.9.2 (Universität Kiel, Germany). The sample size was calculated according to the total morphine dose in 24hr (4.21 in RISS vs. 4.65 in ESP) according to previous studies (9, 10). Based on the following considerations: 0.05 α error and 80% power of the study. Four cases were added to overcome dropout. Therefore, 70 patients will be allocated.

Statistical Analysis Statistical analysis will be done by SPSS v26 (IBM Inc., Chicago, IL, USA). Shapiro-Wilks test and histograms will be used to evaluate the normality of the distribution of data. Quantitative parametric variables will be presented as mean and standard deviation (SD) and compared between the two groups utilizing unpaired Student's t- test. Quantitative non-parametric data will be presented as median and interquartile range (IQR) and will be analyzed by Mann Whitney-test. Qualitative variables will be presented as frequency and percentage (%) and will be analyzed utilizing the Chi-square test or Fisher's exact test when appropriate. A two tailed P value < 0.05 will be considered statistically significant.

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Emad LM Ahmed, Lecturer; Phone Number: +201006531896; Email: emad.ahmmed@must.edu.eg
• Study Contact Backup: Name: Mohamed M Ahmed, Resident; Phone Number: 0201147888382; Email: Manmoh980@gmail.com

Study Locations

• Egypt
  • Giza Governorate
    • Giza, Giza Governorate, Egypt, 15525
      • Souad Kafafi University Hospital (SKUH), Faculty of Medicine, MUST

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Patients scheduled for laparoscopic abdominal surgery (e.g., cholecystectomy, colectomy, sleeve gastrectomy, hernia repair, appendectomy).
• Age from 18 - 60 years old.
• Both sexes.
• American Society of Anesthesiology (ASA) classification I, II. (i.e., ASA I: a normal healthy patient; ASA II: patients with mild controlled systemic disease.

Exclusion Criteria:

• Patients who refuse the research consent.
• Allergy to local anesthetic drugs.
• Cardiac arrhythmia.
• Bleeding tendency (including pre-existing blood disease and patients on full anticoagulant therapy).
• Morbid obese patients (BMI>35 kg/m2)
• Vascular compromise of lower extremity (e.g., Burger disease, Raynaud's disease).
• Connective tissue disease (e.g., Scleroderma).
• Suspected malignancy or intra-abdominal infection.

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: Group A (n=35): Ultrasound-guided RISS block.; The patient will be positioned in the lateral decubitus with the ipsilateral arm abducted to move the scapula laterally and open the intercostal and subscapular spaces. A high-frequency linear probe (10-14 MHz) will be applied 1-2 cm medial to the medial scapular border in an oblique-sagittal plane at the T5-T6 level. Using an in-plane approach, a 22 G, 80 mm block needle will be advanced from superomedial to inferolateral (cephalocaudal) until the tip lies between RM and ICM. After negative aspiration and hydrodissection with 1-2 ml saline, 10 ml of the prepared solution (1% lidocaine + 0.25% bupivacaine + 4 mg dexamethasone) will be injected in 5 ml aliquots, with real-time observation of spread deep to RM. The probe will then be slid caudally and laterally to the T8-T9 level to visualize the fascial plane at the mid-axillary line between the serratus anterior (SA) muscle and the external intercostal muscle to inject the other 10 ml of local anesthetic.	Procedure: Group A (n=35): Ultrasound-guided RISS block (RISS): The patient will be positioned in the lateral decubitus with the ipsilateral arm abducted to move the scapula laterally and open the intercostal and subscapular spaces. A high-frequency linear probe (10-14 MHz) will be applied 1-2 cm medial to the medial scapular border in an oblique-sagittal plane at the T5-T6 level. Using an in-plane approach, a 22 G, 80 mm block needle will be advanced from superomedial to inferolateral (cephalocaudal) until the tip lies between RM and ICM. After negative aspiration and hydrodissection with 1-2 ml saline, 10 ml of the prepared solution (1% lidocaine + 0.25% bupivacaine + 4 mg dexamethasone) will be injected in 5 ml aliquots, with real-time observation of spread deep to RM. The probe will then be slid caudally and laterally to the T8-T9 level to visualize the fascial plane at the mid-axillary line between the serratus anterior (SA) muscle and the external intercostal muscle to inject the other 10 ml of local anesthetic.
Active Comparator: Group B (n=35): Receiving ultrasound-guided lower thoracic ESP block; The patient will be positioned laterally. A linear probe will be placed 3 cm lateral to the posterior midline at the T8-T9 level to identify the transverse process (TP) and erector spinae muscle (ESM). A 22 G, 80 mm Echogenic block needle will be advanced in-plane from cranial to caudal until the tip rests deep to ESM but superficial to the TP. After negative aspiration, 20 ml of the prepared solution (1% lidocaine + 0.25% bupivacaine + 4 mg dexamethasone) will be injected in 5 ml aliquots, with real-time ultrasound confirmation of longitudinal spread cranially and caudally along the fascial plane. The block will be performed bilaterally following the same stepsA solution composed of 20 ml mixed xylocaine 1% + 0.25 % bupivacaine + 4 mg dexamethasone on each side.	Procedure: Group B (n=35): Ultrasound-guided lower thoracic ESP block; The patient will be positioned laterally. A linear probe will be placed 3 cm lateral to the posterior midline at the T8-T9 level to identify the transverse process (TP) and erector spinae muscle (ESM). A 22 G, 80 mm Echogenic block needle will be advanced in-plane from cranial to caudal until the tip rests deep to ESM but superficial to the TP. After negative aspiration, 20 ml of the prepared solution (1% lidocaine + 0.25% bupivacaine + 4 mg dexamethasone) will be injected in 5 ml aliquots, with real-time ultrasound confirmation of longitudinal spread cranially and caudally along the fascial plane. The block will be performed bilaterally following the same stepsA solution composed of 20 ml mixed xylocaine 1% + 0.25 % bupivacaine + 4 mg dexamethasone on each side.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative analgesia	Pain will be assessed using a Numerical Rating Scale (NRS) (0-10 scale). Will be measured by NRS at 0, 6, 12, 18, and 24 hours postoperative; Mild pain (NRS 1-3) will be treated with 1 g paracetamol IV every six hours (maximum 4 g/day).; Moderate pain (NRS 4-6) will receive the same paracetamol regimen plus ketorolac 30 mg IV every eight hours (maximum 120 mg/day).; Severe pain (NRS 7-10) will receive the above plus 0.1 mg/kg IV morphine when indicated.	from 0 to 24 hours postoperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total morphine consumption (mg) in 24 h.	Doses of morphine given intravenous postoperatively according to severity of pain (NRS > 6) during the first 24 hours postoperatively	from 0 to 24 hours postoperative
Intra-operative vital signs (HR)	Measuring the patient's heart rate (HR) before induction of anesthesia and every 15 minutes during surgery.	Before induction of anesthesia till the end of surgery
• Intra-operative vital signs: Mean Blood Pressure (MBP)	Measuring the patient's Mean Blood Pressure (MBP) before induction of anesthesia and every 15 minutes during surgery.	Before induction of anesthesia till the end of surgery
Possible complications	pneumothorax, LAST, vascular puncture	Intra- and post-operatively for 24 hours.

Collaborators and Investigators

• Sponsor: Misr University for Science and Technology
• Investigators: Study Chair: Manar M ElKholy, Profesor, Prof. of Anesth, Kasr Alainy hospital, Faculty of Medicine, Cairo University; Study Director: Mohamed Abdelaziz Taha, Assist. Prof., Assist. Prof. of Anesth, Souad Kafafi University hospital, Faculty of Medicine, MUST; Study Director: Ahmed SK Elkhodary, Lecturer, Lecturer of surgery at Souad Kafafi University hospital, Faculty of Medicine, MUST

Publications and helpful links

General Publications

• Lin J, Wu H, Wen Z, Li Y, Jiang C, Lin B, Gu Y. Subserratus Anterior Plane Block vs Thoracic Paravertebral Block for Postoperative Analgesia in Laparoscopic Radical Nephrectomy: Protocol for a Randomized Controlled, Double-Blind, Non-Inferiority Clinical Trial. J Pain Res. 2025 Mar 25;18:1615-1625. doi: 10.2147/JPR.S506226. eCollection 2025.
• Wang S, Wang H, Chen X, Li M, Xu D. Ultrasound-Guided Continuous Rhomboid Intercostal and Sub-Serratus Plane Block Comparison of Thoracoscopic Intercostal Nerve Block After Thoracoscopic Surgery: A Prospective Randomized Controlled Study. J Pain Res. 2024 Dec 21;17:4471-4481. doi: 10.2147/JPR.S484092. eCollection 2024.
• Elsharkawy H, Maniker R, Bolash R, Kalasbail P, Drake RL, Elkassabany N. Rhomboid Intercostal and Subserratus Plane Block: A Cadaveric and Clinical Evaluation. Reg Anesth Pain Med. 2018 Oct;43(7):745-751. doi: 10.1097/AAP.0000000000000824.

Study record dates

Study Major Dates

• Study Start (Estimated): May 20, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: April 28, 2026
• First Submitted That Met QC Criteria: May 13, 2026
• First Posted (Actual): May 18, 2026

Study Record Updates

• Last Update Posted (Actual): May 18, 2026
• Last Update Submitted That Met QC Criteria: May 13, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Laparoscopic surgery; Rhomboid Intercostal block; Erector Spine Plane Block
• Other Study ID Numbers: 2025/0124

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Demographic Information: Age, sex, race, and other relevant demographic details.

Baseline Characteristics: Health status, medical history, and any pre-existing conditions prior to the trial.

Treatment Assignment: Information on the intervention or treatment each participant received.

Outcome Measures: Data on primary and secondary outcomes as defined in the trial protocol.

Adverse Events: Reports of any side effects or adverse events experienced by participants during the trial.

Follow-up Data: Information collected during follow-up periods, including long-term outcomes

• IPD Sharing Time Frame: may 2026 to December 2026

IPD Sharing Access Criteria

Researchers:

Who: Academic researchers, industry scientists, and regulatory agencies. What: Full IPD, including demographic data, treatment assignments, and outcome measures.

How: Through data sharing platforms or repositories after submitting a research proposal and obtaining necessary approvals.

Regulatory Authorities:

Who: Agencies like the FDA or EMA. What: Full IPD and supporting documentation for oversight and review. How: Direct access during the review process of clinical trial applications.

Data Sharing Initiatives:

Who: Collaborating institutions and consortia. What: Aggregated or anonymized IPD for meta-analyses or systematic reviews. How: Via established partnerships and shared databases.

Public and Patient Advocacy Groups:

Who: Organizations seeking to promote transparency. What: Summary data and aggregated results, but not individual-level data. How: Through publicly available reports or dashboards.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

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