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Prospective, Randomized Double-Blind Study: Does Decreasing Interscalene Nerve Block Volume for Surgical Anesthesia
Daniel B Maalouf1, Shawna M Dorman, Joseph Sebeo
1From the *Department of Anesthesiology, Hospital for Special Surgery; †Department of Anesthesiology, Perioperative Care, and Pain Medicine, NYU Langone Medical Center; and ‡Department of Biostatistics, Hospital for Special Surgery, New York, NY; ¶Private practice.
A reduced volume (20 mL) of ultrasound-guided interscalene nerve block for shoulder arthroscopy preserves handgrip strength postoperatively compared to a larger volume (40 mL). This approach maintains block success and patient satisfaction without compromising analgesia duration.
Area of Science:
- Anesthesiology
- Regional Anesthesia
- Musculoskeletal Surgery
Background:
- Ultrasound-guided interscalene nerve blocks are common for shoulder arthroscopy.
- Optimizing local anesthetic volume is crucial for balancing efficacy and side effects.
Purpose of the Study:
- To compare the effects of 20 mL versus 40 mL of a mepivacaine-bupivacaine mixture in ultrasound-guided interscalene blocks.
- To evaluate the impact on ipsilateral handgrip strength and other postoperative outcomes.
Main Methods:
- A randomized, double-blind, prospective study involving 154 patients undergoing ambulatory shoulder arthroscopy.
- Patients received either a 20 mL (intervention) or 40 mL (control) interscalene block under ultrasound guidance.
- Primary outcome: change in ipsilateral handgrip strength in the postanesthesia care unit (PACU).
Main Results:
- The 20 mL group demonstrated significantly greater postoperative handgrip strength (2.3 kg difference, P=0.009).
- Hoarseness incidence was lower in the 20 mL group (OR 0.26, P=0.015).
- Patient satisfaction and analgesia duration were comparable between groups.
Conclusions:
- A 20 mL volume for ultrasound-guided interscalene blocks preserves ipsilateral handgrip strength post-shoulder arthroscopy.
- This reduced volume provides comparable block success, analgesia duration, and patient satisfaction to a 40 mL volume.
- This finding supports optimizing local anesthetic volume in regional anesthesia for ambulatory surgery.
