Interscalene vs Phrenic-sparing Blocks in Obesity and Effect of Maximum Inspiratory Pressure
Eligible age
18+ yrs
Accepts
All genders
Locations
1 state
Healthy volunteers
No
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About this study
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).
Sponsor: University of North Carolina, Chapel Hill
You may qualify if…
- ✓ Age ≥ 18 years (self-report, confirmed on chart).
- ✓ Body-mass index ≥ 35 kg m\^2 at the pre-operative clinic visit (chart).
- ✓ Scheduled for elective unilateral shoulder surgery (arthroscopy, arthroplasty, rotator cuff repair, reverse arthroplasty) under general anesthesia at UNC Hospitals
- ✓ Planned use of a single-injection regional brachial-plexus block for postoperative analgesia (anesthesia record).
- ✓ Able to perform a maximal-inspiratory-pressure (MIP) maneuver at screening, producing two reproducible efforts (bedside test)
- ✓ Able to read or understand English and provide written informed consent (consent discussion).
You may not qualify if…
- ✕ Emergent or trauma shoulder procedure or case converted to open surgery (schedule/chart).
- ✕ Pregnancy confirmed by point-of-care urine test on day of surgery (POC test). Prisoner status or legal incapacity to consent (chart/interview).
- ✕ Severe pulmonary disease: GOLD stage 3-4 COPD, restrictive lung disease unrelated to obesity with FVC \< 50 % predicted, baseline dyspnea Borg ≥ 3, or home oxygen therapy (pulmonary clinic notes, patient interview).
- ✕ Severe heart disease- Severe valvular heart disease, Congestive Heart Failure NYHA Class III or IV, Obstructive Coronary Artery Disease with Angina
- ✕ Neuromuscular disorders affecting respiratory muscles (e.g., ALS, myasthenia gravis) or known diaphragmatic paralysis (chart).
- ✕ Coagulopathy (platelets \< 100 × 10/ L or INR \> 1.5) or local infection at block sites (pre-op labs/assessment).
- ✕ Anemia and hemoglobinopathies: Hgb \<10 g/dl, clinically significant hemoglobinopathy.
- ✕ Allergy to bupivacaine, dexamethasone, or ultrasound gel (self-report).
Where it's recruiting
Chapel Hill
Source: ClinicalTrials.gov · NCT07216820 · last updated 2026-01-28