Sensory Analysis and Cutaneous Mapping of Different Regional Anesthesia Techniques

Official title

Sensory Analysis and Cutaneous Mapping of Different Regional Anesthesia Techniques in Laparoscopic Cholecystectomy Surgery: A Prospective Observational Study

Overview

This prospective observational study aims to evaluate and compare the sensory block distribution and regression patterns of two regional anesthesia techniques - External Oblique Plane Block (EOPB) and Serratus Intercostal Plane Block (SIPB) - in patients undergoing laparoscopic cholecystectomy. Thirty adult patients (ASA I-III, BMI ≤ 35 kg/m², ≥50 kg) scheduled for elective laparoscopic cholecystectomy procedures will be included, with 20 in each block group. Sensory block areas will be assessed using pinprick test, and dermatomal mapping will visualize the spread. The findings are expected to improve understanding of block behavior and guide multimodal analgesia strategies in laparoscopic cholecystectomy.

Detailed description

This single-center, prospective observational study will be conducted at Samsun University Training and Research Hospital operating rooms between November 2025 and June 2026.

The study will include patients aged 18-75 years, classified as ASA I-III, who are scheduled for elective laparoscopic cholecystectomy and have provided written informed consent. For pain management, these patients will undergo either serratus intercostal plane block (SIPB) or external oblique plane block (EOPB) under ultrasound guidance. Patients receiving one of these two block techniques will be observed, and the sensory block areas created will be evaluated.

Both blocks will be performed bilaterally and under ultrasound guidance immediately before surgery. 0.25% bupivacaine will be used for the block applications, and 25 mL of local anesthetic will be injected into each side (a total of 50 mL). Thirty minutes after the block, patients will be evaluated for cutaneous sensory block using the "pinprick test." This evaluation will be standardized according to specific dermatome levels, covering the midline and both abdominal quadrants, in order to describe sensory loss on the skin.

The data obtained will be analyzed to determine the dermatomal spread and the minimum and maximum areas of effect of the blocks. Additionally, findings related to block application time will be recorded observationally. A comparison between the groups will be made, and the degree of overlap between the sensory block areas and the surgical incision site will be evaluated.

Interventions

• Procedure External Oblique Plane Block (EOPB)
  Ultrasound-guided External Oblique Plane Block (EOPB) performed bilaterally using 0.25% bupivacaine (25 mL per side, total 50 mL) for postoperative analgesia in laparoscopic cholecystectomy.
• Procedure Serratus Intercostal Plane Block (SIPB)
  Ultrasound-guided Serratus Intercostal Plane Block (SIPB) performed bilaterally using 0.25% bupivacaine (25 mL per side, total 50 mL) for postoperative analgesia in laparoscopic cholecystectomy.

Primary outcome measures

• Cutaneous Sensory Block Area of EOPB and SIPB [Time frame: 30 minutes after block application]

Secondary outcome measures (3)

• Coverage of Surgical Port Entry Sites by the Sensory Block Area [Time frame: 30 minutes after block application]
• Maximum and Minimum Spread of the Cutaneous Sensory Block Area [Time frame: 30 minutes after block application]
• Block Application Duration [Time frame: From needle insertion to completion of local anesthetic injection]

Eligibility criteria

Inclusion criteria

• Patients scheduled for elective laparoscopic cholecystectomy surgery and who have received a regional anesthesia technique for this purpose.
• Aged between 18-75 years.
• Belonging to ASA I-III group.
• Having provided written informed consent.

Exclusion criteria

• Patients who refuse to participate.
• Patients who did not receive a block.
• Patients classified as ASA IV.
• History of previous abdominal surgery (affecting the laparoscopic approach).
• Patients with cognitive dysfunction or inability to cooperate.
• Patients diagnosed with psychiatric disorders (schizophrenia, mania, depression, etc.).
• Patients who have been using antipsychotic medication for more than 4 weeks.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

Turkey (Türkiye) · 1 center

• Samsun University, Samsun Training and Research Hospital — Samsun

Publications

• Nielsen TD, Moriggl B, Barckman J, Kolsen-Petersen JA, Soballe K, Borglum J, Bendtsen TF. The Lateral Femoral Cutaneous Nerve: Description of the Sensory Territory and a Novel Ultrasound-Guided Nerve Block Technique. Reg Anesth Pain Med. 2018 May;43(4):357-366. doi: 10.1097/AAP.0000000000000737. PMID 29381568
• Dost B, Turunc E, Kaya C, Sahin CA, Genc C, Yucel SM, Demirag MK, Karakaya D. Maximum extension and regression rate of cutaneous sensory block: superficial vs. deep parasternal intercostal plane blocks in patients undergoing open cardiac surgery. J Clin Anesth. 2025 Jul;105:111888. doi: 10.1016/j.jclinane.2025.111888. Epub 2025 May 30. PMID 40449315
• Genc C, Tulgar S, Akgun C, Avci MA, Yesilyurt B, Yildiz B, DE Cassai A. Maximum extension and regression rate of cutaneous sensory block obtained with the external oblique intercostal block or the modified thoracoabdominal nerves block through perichondrial approach in patients undergoing laparoscopic cholecystectomy. Minerva Anestesiol. 2024 Nov;90(11):979-988. doi: 10.23736/S0375-9393.24.18213-2 PMID 39545654

Identifiers

NCT: NCT07445854 · GOKAEK 2025/20/13

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗