Shoulder Surgery, Obesity
Conditions
Keywords
interscalene block, phrenic-sparing block, brachial plexus block
Brief summary
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).
Interventions
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)
PROCEDUREPhrenic-Sparing Block Combination (Experimental)
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)
Infraclavicular: Adminstered as 15 mL (75 mg) injection (together with dexamethasone). Distal Suprascapular: Adminstered as 12 mL (60 mg) injection (together with dexamethasone).
DRUGDexamethasone 4mg
Adminstered as applicable for infraclavicular and distal suprascapular: as 1 mL (4 mg) injection (together with bupicacaine 0.5%).
Sponsors
University of North Carolina, Chapel Hill
American Society of Regional Anesthesia
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of Early Postoperative Respiratory Compromise | Within 60 minutes after arrival to PACU | Composite outcome defined as either (a) a Modified Borg Dyspnea Score ≥ 3 in the post-anesthesia care unit (PACU, 30-60 minutes after surgery) or (b) continued need for supplemental oxygen at the PACU assessment. Outcome Type: Primary Unit of Measure: Percentage of participants meeting composite endpoint. |
| Effect Modification by Preoperative Maximum Inspiratory Pressure (MIP) | Baseline (preoperative MIP test) and PACU assessment (30-60 minutes post-surgery). | Assess whether the magnitude of treatment benefit from the phrenic-sparing block varies by baseline inspiratory-muscle strength. The effect is modeled as the interaction between block type and continuous MIP (cm H₂O) on the composite respiratory-compromise endpoint. Unit of Measure: Interaction odds ratio (per 10 cm H₂O decrement in MIP). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Lowest Oxygen Saturation (SpO₂) in PACU | From PACU arrival to discharge (typically 60-120 minutes) | Minimum oxygen saturation recorded by pulse oximetry during the PACU stay Unit of Measure: Percent (%) |
| Total Duration of Supplemental Oxygen Use | 0-24 hours post-surgery. | Total number of hours on oxygen from PACU arrival until hospital discharge (maximum 24 hours). Unit of Measure: Hours. |
| Post-Induction Opioid Consumption | 0-6 hours post-surgery. | Total opioid dose administered from anesthesia induction to PACU discharge, converted to oral morphine milligram equivalents (OMME). Unit of Measure: mg OMME. |
| Diaphragmatic Excursion Change from Baseline | Baseline (pre-block) and 30-60 minutes post-surgery in PACU. | Percent change in diaphragmatic excursion (ultrasound-measured) from baseline to PACU. Unit of Measure: Percent change (%). |
| PACU Pain Score | Within 1 hour after PACU arrival. | Numeric Rating Scale (NRS) for pain recorded at 30-60 minutes post-surgery. Unit of Measure: 0-10 NRS scale. |
Countries
United States
Contacts
CONTACTMonika Nanda
PRINCIPAL_INVESTIGATORMonika Nanda
University of North Carollina at Chapel Hill
Outcome results
None listed