Interscalene vs Phrenic-sparing Blocks in Obesity and Effect of Maximum Inspiratory Pressure

Part of paid clinical trials in Chapel Hill, North Carolina.

Sponsor
University of North Carolina, Chapel Hill
Study ID
NCT07216820
Status
Recruiting
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Conditions

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • Ultrasound-Guided Interscalene Brachial Plexus Block — PROCEDURE
    Single 16 mL injection (15 mL 0.5 % bupivacaine + 1 mL dexamethasone 4 mg) at the C5-C6 root level under ultrasound guidance. Performed pre-operatively as standard care for shoulder surgery. Arm Cross-Reference: Standard Interscalene Block (Control)
  • Phrenic-Sparing Block Combination (Experimental) — PROCEDURE
    Infraclavicular: 15 mL (75 mg) 0.5 % bupivacaine + 1 mL dexamethasone (4 mg) injected around the cords of the brachial plexus beneath the clavicle under ultrasound guidance. Distal Suprascapular: 12 mL (60 mg) 0.5 % bupivacaine + 1 mL (4 mg) dexamethasone injected at the suprascapular notch under ultrasound guidance to provide complete shoulder coverage while minimizing phrenic nerve involvement. Total local anesthetic dose = 135 mg bupivacaine + 8 mg dexamethasone. Arm Cross-Reference: Phrenic-Sparing Block Combination (Experimental)
  • Bupivacaine HCl 0.5% Injectable Solution — DRUG
    Infraclavicular: Adminstered as 15 mL (75 mg) injection (together with dexamethasone). Distal Suprascapular: Adminstered as 12 mL (60 mg) injection (together with dexamethasone).
  • Dexamethasone 4mg — DRUG
    Adminstered as applicable for infraclavicular and distal suprascapular: as 1 mL (4 mg) injection (together with bupicacaine 0.5%).

Study Details

The goal of this clinical trial is to learn whether a phrenic-sparing nerve block can lower early breathing problems after shoulder surgery in adults with obesity, and whether a simple breathing-strength test (maximum inspiratory pressure, MIP) helps identify who is at higher risk. The main questions are: Does the phrenic-sparing approach reduce breathlessness or oxygen need in the recovery room (30-60 minutes after arrival)? Do patients have similar pain control and opioid use compared with the standard interscalene block (ISB)? Are there any breathing-related complications or unplanned admissions within 24 hours? Researchers will compare the phrenic-sparing block (infraclavicular + distal suprascapular) to the standard ISB, both commonly used at UNC. Participants will: Have a quick MIP breath test before surgery (and, if age ≥65, a brief thigh muscle ultrasound). Be randomly assigned to receive either the standard ISB or the phrenic-sparing block (both ultrasound-guided and part of routine care). Receive usual anesthesia/surgery; have a brief recovery check at 30-60 minutes (breathlessness score, oxygen use, oxygen level). Have pain medicines recorded from anesthesia start to PACU discharge; the team may review the chart up to 24 hours and make a short follow-up call (24-48 hours).

Key Dates

Start date
Jan 21, 2026
Status verified
Jan 2026
Primary completion
Nov 1, 2027
Completion
Nov 15, 2027

Study Design

Enrollment
68 participants (estimated)
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT

Arms

  • Active Comparator: Arm 1: Standard Interscalene Block
    Standard Interscalene Brachial Plexus Block (Control) Description: Participants receive a single 16 mL interscalene block at the C5-C6 level under ultrasound guidance. The injectate contains 15 mL of 0.5% bupivacaine HCl (75 mg) mixed with 1 mL preservative-free dexamethasone (4 mg).
  • Experimental: Arm 2: Phrenic-Sparing Block Combination
    Combined Infraclavicular + Distal Suprascapular Block (Phrenic-Sparing Technique) Description: Participants receive two ultrasound-guided peripheral nerve blocks designed to minimize phrenic nerve involvement: Infraclavicular block: 15 mL 0.5% bupivacaine + 1 mL dexamethasone (total 16 mL) Distal suprascapular block: 12 mL 0.5% bupivacaine + 1 mL dexamethasone (total 13 mL) Total local-anesthetic dose = 135 mg bupivacaine + 8 mg dexamethasone, within accepted safety limits.

Primary Outcome Measure

Incidence of Early Postoperative Respiratory Compromise [ Time Frame: Within 60 minutes after arrival to PACU ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
University of North Carolina HospitalsChapel HillNorth Carolina27599
Monika Nanda
[email protected]
919-966-5136

Find similar trials in Chapel Hill, NC

By condition
Obesity / overweight
By specialty
EndocrinologyMetabolic healthWeight loss
By research site
University of North Carolina Hospitals· Chapel Hill, NC

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