Dose-Finding Study: MEV90 for Local Anesthetic in Interscalene Block for Supraclavicular Nerves Block
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Ultrasound-Guided Interscalene Block with Bupivacaine.
- Who it may be relevant to
- Registry conditions: Brachial Plexus Blockade, Shoulder Surgery, Superficial Cervical Plexus Block. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Chile
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Minimum Effective Volume (MEV90) of Local Anesthetic Required for Ultrasound-Guided Interscalene Block for Supraclavicular Nerve Block: A Dose-Finding Study
Overview
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.
Interventions
- Drug 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 supracl
Primary outcome measures
- Minimum Effective Volume (MEV90) for Supraclavicular Nerve Block via Interscalene Approach [Time frame: 30 minutes after completion of the block]
Secondary outcome measures (7)
- Sensorimotor Block Score for Interscalene Block [Time frame: Every 5 minutes up to 30 minutes after block completion.]
- Onset Time of Sensorimotor Block [Time frame: Up to 30 minutes after block completion.]
- Sensory Block at Shoulder Arthroscopy Portals [Time frame: 30 minutes after block completion.]
- Sensory Block of Auricular, Occipital, and Transverse Cervical Nerves [Time frame: 30 minutes after block completion.]
- Pain Score During Block Procedure [Time frame: Immediately after block completion.]
- Block Performance Times [Time frame: During block procedure.]
- Incidence of Block-Related Adverse Events [Time frame: From block completion until end of surgery.]
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
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- N/A
- Model
- Single group
- Masking
- Open label
- Primary purpose
- Supportive care
Study locations
Chile · 1 center
- Hospital del Trabajador — Providencia
Identifiers
NCT: NCT07338916 · Project Nº34, 2025 · 251213001