Diaphragm-Sparing Regional Anesthesia Techniques for Shoulder Surgery

Comparison of Interscalene Brachial Plexus Block Versus the Combination of Suprascapular and Infraclavicular Brachial Plexus Block for Shoulder Surgery: A Randomized Controlled Trial With Diaphragmatic Function Assessment

This study will compare two regional anesthesia techniques for shoulder surgery and evaluate their effects on diaphragmatic function. The standard regional anesthesia technique for shoulder surgery is the interscalene brachial plexus block (ISB), which provides effective analgesia but is frequently associated with ipsilateral hemidiaphragmatic paresis due to phrenic nerve involvement.

An alternative diaphragm-sparing strategy is the combination of a suprascapular nerve block (SSNB) and an infraclavicular brachial plexus block (ICB), which may reduce the risk of diaphragmatic dysfunction while maintaining effective analgesia for shoulder surgery.

All participants will receive ultrasound-guided regional anesthesia prior to surgery and will be randomly assigned to one of two groups:

Group 1: Interscalene brachial plexus block Group 2: Suprascapular nerve block combined with infraclavicular brachial plexus block The primary aim of this study is to determine whether the diaphragm-sparing technique reduces the incidence of hemidiaphragmatic paresis while providing analgesia comparable to the standard interscalene block. Diaphragmatic movement will be assessed using ultrasound before and after block placement. Secondary outcomes include postoperative pain intensity, opioid consumption, pulmonary function parameters, and block-related complications.

The interscalene brachial plexus block (ISB) is widely used for anesthesia and postoperative analgesia in shoulder surgery because of its reliable and effective pain control. However, ISB is commonly associated with ipsilateral hemidiaphragmatic paresis due to unintended phrenic nerve blockade, which may impair respiratory function, particularly in older patients and in those with pre-existing pulmonary disease.

The combination of a suprascapular nerve block (SSNB) and an infraclavicular brachial plexus block (ICB) has been proposed as a diaphragm-sparing alternative for shoulder surgery. This approach may provide adequate surgical anesthesia and postoperative analgesia while minimizing the risk of diaphragmatic dysfunction.

This randomized controlled trial will compare the interscalene brachial plexus block with the combined suprascapular and infraclavicular brachial plexus block in patients undergoing elective shoulder surgery. Diaphragmatic function will be evaluated using ultrasound imaging before block performance and after block placement. Additional outcomes will include postoperative pain intensity at rest and during movement, opioid consumption, pulmonary function parameters, block-related complications, length of hospital stay, and patient satisfaction.

Inclusion Criteria:

• Age ≥ 65 years
• Elective shoulder surgery
• ASA I-III
• Planned use of regional anesthesia
• Signed written informed consent

Exclusion Criteria:

• Allergy to local anesthetics
• Planned continuous catheter technique
• BMI >40 kg/m²
• Coagulopathy or anticoagulation
• Pre-existing phrenic nerve palsy
• Neurological disorder of the operative limb
• Pregnancy or breastfeeding
• Participation in another clinical trial within 30 days