Dose-Finding Study: MEV90 for Local Anesthetic in Interscalene Block for Supraclavicular Nerves Block
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorHospital del Trabajador de Santiago
About this trial
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 criteria
This trial does not accept healthy volunteersQualifiers
Age ≥ 18 years
ASA physical status I to III
Body Mass Index (BMI) between 18 and 35 kg/m²
Weight ≥ 50 kg
Disqualifiers
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)
Trial design
Design model
Single group
Treatments tested in this trial
Ultrasound-Guided Interscalene Block with Bupivacaine
DrugParticipants 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).
Treatment groups
55 Participants
are divided into 1 treatment groupGroup A: Minimum Effective Volume 90 (MEV90)Experimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Minimum Effective Volume (MEV90) for Supraclavicular Nerve Block via Interscalene Approach
The primary outcome is the calculation of the minimum effective volume of local anesthetic (MEV90) required to achieve complete sensory block of the supraclavicular nerves following a single-shot ultrasound-guided interscalene brachial plexus block. Success is defined as absence of cold and touch sensation at the midpoint of the clavicle, assessed using an ice test.
Time frame
30 minutes after completion of the blockSecondary outcomes
1
Sensorimotor Block Score for Interscalene Block
Composite score (0-8 points) assessing sensory and motor block in C5-C6 dermatomes using ice test and motor function (shoulder abduction and external rotation). Success defined as ≥6 points.
Time frame
Every 5 minutes up to 30 minutes after block completion.2
Onset Time of Sensorimotor Block
Interval (minutes) between completion of local anesthetic injection and achievement of ≥6 points on the sensorimotor scale.
Time frame
Up to 30 minutes after block completion.3
Sensory Block at Shoulder Arthroscopy Portals
Presence or absence of cold and touch sensation at anterior, lateral, and posterior portal sites using ice test.
Time frame
30 minutes after block completion.4
Sensory Block of Auricular, Occipital, and Transverse Cervical Nerves
Assessment of sensory block in territories of auricular major, occipital minor, and transverse cervical nerves using ice test.
Time frame
30 minutes after block completion.Sponsors and contacts
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Source ClinicalTrials.gov