Dose-Finding Study: MEV90 for Local Anesthetic in Interscalene Block for Supraclavicular Nerves Block

NCT ID: NCT07338916

Last Updated: 2026-01-21

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 55 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2026-02-28
• Study Completion Date: 2026-08-31

Brief Summary

This study aims to determine the minimum effective volume (MEV90) of local anesthetic required to achieve sensory block of the supraclavicular nerves when performing a single-shot ultrasound-guided interscalene brachial plexus block (ISB). These nerves provide sensation to the skin over the clavicle and shoulder and are often involved in surgeries such as shoulder arthroscopy and clavicle repair.

Detailed Description

This prospective dose-finding study seeks to determine the minimum effective volume (MEV90) of local anesthetic required to achieve sensory block of the supraclavicular nerves following a single-shot ultrasound-guided interscalene brachial plexus block (ISB). These nerves, branches of the superficial cervical plexus, provide cutaneous innervation over the clavicle and shoulder and may contribute to postoperative pain after shoulder and clavicular surgery. Establishing MEV90 is clinically relevant to optimize analgesia while minimizing the risk of local anesthetic systemic toxicity.

The study employs a biased coin up-and-down sequential design, commonly used in regional anesthesia dose-finding trials. The initial volume is 12 mL of bupivacaine 0.5% with epinephrine (5 µg/mL), with subsequent volumes adjusted in 2 mL increments based on the prior patient's response. The maximum permitted volume is 30 mL.

All blocks are performed under ultrasound guidance by experienced anesthesiologists (≥60 ISBs), following standard safety protocols.

This intervention does not introduce additional risk beyond routine care, as ISB is the gold standard for shoulder surgery analgesia. Results will inform whether a single interscalene injection provides adequate coverage of supraclavicular nerves or if a separate cervical plexus block is necessary for procedures involving both plexuses, such as clavicle surgery. Findings may refine volume recommendations, improve analgesic strategies, and reduce unnecessary drug exposure.

Conditions

Brachial Plexus Blockade; Shoulder Surgery; Superficial Cervical Plexus Block

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: SUPPORTIVE_CARE
• Blinding Strategy: NONE

Study Groups

Minimum Effective Volume 90 (MEV90)

Participants in this arm will receive a single-shot ultrasound-guided interscalene brachial plexus block as part of standard perioperative analgesia for shoulder arthroscopy. The intervention consists of injecting bupivacaine 0.5% with epinephrine (5 µg/mL) between the anterior and middle scalene muscles at the level of the C5-C6 nerve roots, using an in-plane technique under real-time ultrasound guidance.

Group Type: EXPERIMENTAL

Ultrasound-Guided Interscalene Block with Bupivacaine

Intervention Type: DRUG

Participants will receive a single-shot interscalene brachial plexus block performed under real-time ultrasound guidance. The block targets the C5-C6 nerve roots between the anterior and middle scalene muscles using an in-plane technique. The local anesthetic is bupivacaine 0.5% with epinephrine (5 µg/mL). The injected volume ranges from 12 mL to 30 mL, determined by a dose-finding algorithm (biased coin up-and-down sequential design) to calculate the minimum effective volume (MEV90) for supraclavicular nerve block. All procedures are performed by experienced anesthesiologists following standard safety protocols, including incremental injection with aspiration and continuous monitoring (ECG, SpO₂, non-invasive blood pressure).

Interventions

Ultrasound-Guided Interscalene Block with Bupivacaine

Participants will receive a single-shot interscalene brachial plexus block performed under real-time ultrasound guidance. The block targets the C5-C6 nerve roots between the anterior and middle scalene muscles using an in-plane technique. The local anesthetic is bupivacaine 0.5% with epinephrine (5 µg/mL). The injected volume ranges from 12 mL to 30 mL, determined by a dose-finding algorithm (biased coin up-and-down sequential design) to calculate the minimum effective volume (MEV90) for supraclavicular nerve block. All procedures are performed by experienced anesthesiologists following standard safety protocols, including incremental injection with aspiration and continuous monitoring (ECG, SpO₂, non-invasive blood pressure).

Intervention Type: DRUG

Eligibility Criteria

Inclusion Criteria

• Age ≥ 18 years
• ASA physical status I to III
• Body Mass Index (BMI) between 18 and 35 kg/m²
• Weight ≥ 50 kg
• Scheduled for shoulder arthroscopy requiring an interscalene brachial plexus block for analgesia
• Able to provide informed consent

Exclusion Criteria

• Inability to provide informed consent
• Coagulopathy (platelet count ≤100,000; INR ≥1.4)
• Significant pulmonary disease (restrictive or obstructive)
• Renal insufficiency (creatinine ≥1.2 mg/dL)
• Hepatic insufficiency (transaminases ≥100 U/L)
• Allergy to local anesthetics
• Pregnancy
• Pre-existing neuropathy
• Previous surgery in ipsilateral cervical or supraclavicular region
• Contralateral hemidiaphragmatic paralysis or vocal cord paralysis

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Hospital del Trabajador de Santiago

OTHER

Sponsor Role: lead

Responsible Party

Germán Armando Aguilera Ceballos

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Central Contacts

Germán Aguilera, MD

Role: CONTACT

german.aguilera@gmail.com

+56985205514

Other Identifiers

251213001

Identifier Type: OTHER

Identifier Source: secondary_id

Project Nº34, 2025

Identifier Type: -

Identifier Source: org_study_id