Dose-Finding Study: MEV90 for Local Anesthetic in Interscalene Block for Supraclavicular Nerves Block
Minimum Effective Volume (MEV90) of Local Anesthetic Required for Ultrasound-Guided Interscalene Block for Supraclavicular Nerve Block: A Dose-Finding Study
Hospital del Trabajador de Santiago
55 participants
Apr 1, 2026
INTERVENTIONAL
Conditions
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.
Eligibility
Inclusion Criteria6
- 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 Criteria10
- 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
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Interventions
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).
Locations(1)
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NCT07338916