Interscalene vs Phrenic-sparing Blocks in Obesity: Effect of Pre-operative Maximum Inspiratory Pressure in a Randomized Trial
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 68
- 试验地点
- 1
- 主要终点
- Incidence of Early Postoperative Respiratory Compromise
研究概览
简要总结
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).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Single (Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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).
排除标准
- •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
研究组 & 干预措施
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).
干预措施: Ultrasound-Guided Interscalene Brachial Plexus Block (Procedure)
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).
干预措施: Bupivacaine HCl 0.5% Injectable Solution (Drug)
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).
干预措施: Dexamethasone 4mg (Drug)
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.
干预措施: Phrenic-Sparing Block Combination (Experimental) (Procedure)
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.
干预措施: Bupivacaine HCl 0.5% Injectable Solution (Drug)
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.
干预措施: Dexamethasone 4mg (Drug)
结局指标
主要结局
Incidence of Early Postoperative Respiratory Compromise
时间窗: 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)
时间窗: 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).
次要结局
- Post-Induction Opioid Consumption(0-6 hours post-surgery.)
- Diaphragmatic Excursion Change from Baseline(Baseline (pre-block) and 30-60 minutes post-surgery in PACU.)
- Lowest Oxygen Saturation (SpO₂) in PACU(From PACU arrival to discharge (typically 60-120 minutes))
- Total Duration of Supplemental Oxygen Use(0-24 hours post-surgery.)
- PACU Pain Score(Within 1 hour after PACU arrival.)