Comparative Evaluation of Diaphragmatic Function Following Interscalene, Anterior Suprascapular, and Costoclavicular Nerve Blocks in Shoulder Surgery

Comparative Evaluation of Diaphragmatic Function Following Interscalene, Anterior Suprascapular, and Costoclavicular Nerve Blocks in Shoulder Surgery

Shoulder surgery causes significant postoperative pain, and ultrasound-guided regional anesthesia is central to its management. The interscalene block (ISB) is the gold standard but frequently causes phrenic nerve paralysis and hemi-diaphragmatic paresis, limiting its use in patients with reduced pulmonary reserve. The suprascapular (SSNB) and costoclavicular (CCB) blocks are proposed diaphragm-sparing alternatives, but data directly comparing all three are limited.

This randomised, double-blinded trial will compare the incidence of hemi-diaphragmatic paresis among ultrasound-guided ISB, SSNB, and CCB in elective shoulder surgery. Seventy-five ASA I-II patients aged 18-70 will be allocated 1:1:1 to one block. The primary outcome is the incidence of hemi-diaphragmatic paresis, measured by ultrasound diaphragmatic excursion before induction and after recovery in the PACU. Secondary outcomes include postoperative pain, analgesic consumption, and patient satisfaction. The investigators hypothesise that SSNB and CCB will cause less hemidiaphragmatic paresis than ISB while providing comparable analgesia.

This randomized, double-blinded, parallel-group trial compares the effect of three ultrasound-guided regional anesthesia techniques on diaphragmatic function in elective shoulder surgery. The interscalene block (ISB), the gold standard, frequently causes phrenic nerve paralysis and hemi-diaphragmatic paresis. The suprascapular (SSNB) and costoclavicular (CCB) blocks preserve analgesia while sparing the phrenic nerve, but direct comparative data among all three are limited.

Seventy-five ASA I-II patients aged 18-70 scheduled for elective shoulder surgery will be randomized 1:1:1 (25 per group) using computer-generated allocation with sealed opaque envelopes. ISB: 10 mL 0.25% bupivacaine with dexmedetomidine 0.5 µg/kg; SSNB: 10 mL of the same mixture; CCB: 20 mL of the same mixture. All blocks are ultrasound-guided and performed before a standardised general anaesthetic.

Diaphragmatic excursion is measured by M-mode ultrasound of both hemidiaphragms at baseline (pre-induction), 30 minutes after the block, and in the PACU at a train-of-four ratio ≥0.9. Hemi-diaphragmatic paresis is graded as Complete (>75% reduction or paradoxical movement), Partial (25-75%), or Normal (0-25%). The primary outcome is its incidence. Secondary outcomes include VAS pain at rest and movement (1, 3, 6, 12, 24 h), analgesic consumption, time to first rescue analgesia, block performance time, complications, and patient satisfaction.

Inclusion Criteria:

Adults of both sexes, aged 18 to 70 years American Society of Anesthesiologists (ASA) physical status I-II Scheduled for elective shoulder surgery

Exclusion Criteria:

Pulmonary disease or baseline diaphragmatic dysfunction Refusal to provide informed consent Pre-existing neuropathy in the operated limb Allergy to local anesthetics Infection at the injection site Coagulopathy Pregnancy