Comparison of Shoulder Anterior Capsular Block and Interscalene Brachial Plexus Block for Shoulder Arthroscopy: A Preliminary Analysis

Introduction: Pain management after shoulder arthroplasty continues to be challenging. Although interscalene brachial plexus block has been accepted to be the gold standard intervention to relieve pain and improve postoperative outcomes by effecting functional rehabilitation and recovery times, usually results in motor block and complications such as hemi-diaphragmatic paralysis are possible to encounter. For this reason, the research for novel techniques to alleviate these outcomes resumes on the anatomical point of view and ultrasonography guidance. Shoulder anterior capsular block is a recently described interfascial and pericapsular block and is shown to be effective in relieving shoulder pain without motor block or complications.

The aim of our study is to reveal a comparison between interscalene brachial plexus block and shoulder anterior capsular block with respect to their efficacy on pain relief during perioperative anesthetic management along with intraoperative hemodynamic stability, and their effect on the quality of arthroscopic visualization for shoulder arthroplasty.

Material method: Patients scheduled for arthroscopic rotator cuff repair after June 30, 2022, are eligible for this study after ethical board approval. Inclusion criteria are (1) patients aged between 18-90 years with American Society of Anaesthesiologists (ASA) Physical Status classification I to III, (2) diagnosed with rotator cuff rupture, and (3) admitted receiving arthroscopic cuff repair surgery. Written informed consent will be obtained from all participants.

Exclusion criteria are refusal to participate in the study, history of neurologic deficits or neuropathy affecting the brachial plexus; infection at the site of the block application; coagulopathy; pre-existing respiratory dysfunction; allergy to local anesthetics; uncooperative patients who cannot reliably answer to verbal pain evaluation.

All patients will receive standard general anesthesia under standard monitorization; induction with 0,03 mg/kg midazolam, 2 mg/kg propofol, 2 mcg/kg fentanyl, 0,6 mg /kg rocuronium followed by 2% MAC sevoflurane in an air-oxygen mixture for maintenance of anesthesia. Randomization is designed with concealed opaque envelope in a 1:1 ratio into 2 block groups (n= 20): interscalene brachial plexus block (Group A) and shoulder anterior capsular block (Group B). All blocks will be performed before surgical incision by a single experienced regional anaesthesiologist (B.Ç.) under ultrasound guidance with the same local anesthetic doses: 0.375 % bupivacaine anesthetic solution of 10 mL and 2 % lidocaine anesthetic solution of 5 mL. The duration of the block procedure will be recorded by the anesthesia technician. Then the investigator will apply dexamethasone 4 mg (IV) after each block and approximately 15 minutes later the patient will be ready for a surgical incision. Intraoperative hemodynamic values (heart rate, systolic, and mean arterial pressure) will be recorded by the same technician. The same analgesia protocol will be applied as an infusion of remifentanil (0.01 to 0.1 μg · kg-1 · min-1) if only needed to maintain the heart rate and mean blood pressure within 20% of pre-induction values and 1 gr paracetamol. At the end of the surgery, the surgeon who is blind to the groups will decide the arthroscopic visualization score.