Comparing phrenic-sparing and interscalene nerve blocks for shoulder surgery in people with obesity

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

Adults with a body mass index ≥35 undergoing elective unilateral shoulder surgery at UNC are randomly assigned to receive either the standard ultrasound-guided interscalene brachial plexus block or a phrenic-sparing combination block (infraclavicular plus distal suprascapular), with standardized local anesthetic and adjuncts. A maximal inspiratory pressure (MIP) measurement is performed before surgery (and thigh muscle ultrasound if age ≥65) to explore whether it predicts respiratory risk. Primary early respiratory outcomes include patient-reported breathlessness and need for supplemental oxygen in the recovery room 30–60 minutes after arrival, with secondary outcomes of pain control, opioid use, and breathing-related complications or unplanned admissions within 24 hours. All procedures and follow-up occur at the University of North Carolina Hospitals using ultrasound-guided single-injection regional techniques.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* 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).

Exclusion Criteria:

* 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).
* Chronic opioid use \> 100 mg oral-morphine equivalents per day in the three months preceding surgery (medication history, PDMP query).
* Prior enrolment in this trial or planned participation in another interventional study that might confound outcomes (research registry).
* Anticipated inability to comply with postoperative assessments (e.g., profound cognitive impairment, expected early transfer to outside facility) as judged by the investigator

Where it's running

• University of North Carolina Hospitals
  Chapel Hill, North Carolina, United States Recruiting

Study contacts

• Principal investigator: Monika Nanda — University of North Carollina at Chapel Hill
• Study coordinator: Monika Nanda
• Email: mnanda@aims.unc.edu
• Phone: 919-966-5136

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.