Interscalene Block vs Serratus Posterior Superior Intercostal Plane Block on Postoperative Analgesia Management After Arthroscopic Shoulder Surgery: A Randomized Prospective Study

Postoperative pain is an important issue in patients who have undergone arthroscopic shoulder surgery. Pain causes a few problems: uncomfortable patients, negative outcomes, and longer rehabilitation. Postoperative effective pain treatment provides early mobilization and shorter hospital stay, thus complications due to hospitalization, such as infection and thromboembolism, may be reduced. Various techniques may be used for postoperative pain treatment. Opioids are one of the most preferred drugs among analgesic agents. Parenteral opioids are generally administered to patients after surgery. However, opioids have undesirable adverse events such as nausea, vomiting, itching, sedation, and respiratory depression (opioid-related adverse events).

Various methods may be performed to reduce the use of systemic opioids and for effective pain treatment following arthroscopic shoulder surgery. Ultrasound (US)-guided brachial plexus blocks, such as interscalene and supraclavicular block, are commonly used. Interscalen brachial plexus block (ISCB) is one of the most preferred techniques among these.

US-guided interfascial plane blocks have been used increasingly due to the advantages of ultrasound in anesthesia practice. Ultrasound (US) guided serratus posterior superior block (SPSPB) is a new interfacial plane block defined by Tulgar et al in 2023. It is based on injection on the serratus posterior superior muscle at the level of the 2nd or 3rd rib. This block provides analgesia in conditions such as interscapular pain, chronic myofascial pain syndromes, scapulocostal syndrome, and shoulder pain. The SPS muscle is located at the C7-T2 level. It attaches to the lateral edges of the second and fifth ribs. It is innervated by the lower cervical and upper intercostal nerves. With the SPS block, these nerves are blocked, and analgesia is provided.

In the cadaveric study of Tulgar et al., it was determined that the spread of the serratus posterior superior interfacial plane block, 7-10 intercostal levels on the left side, only in the superficial fascia of the trapezius muscle. Spread dye was observed at intercostal levels, absent on the right. There was prominent staining on both sides of the deep trapezius muscle. Both the surface and skin of the rhomboid major were stained, while the rhomboid minor was only stained in the skin. SPSP block will provide successful analgesia in procedures involving the thoracic region, such as chronic myofascial pain, breast surgery, thoracic surgery, and shoulder surgery. There is no randomized study in the literature evaluating the effectiveness of the SPSP block for postoperative analgesia management after shoulder surgery.

This study aims to compare the efficacy of the US-guided SPSIPB and ISCB for postoperative analgesia management after arthroscopic shoulder surgery. The primary aim is to compare postoperative opioid consumption (fentanyl), and the secondary aim is to evaluate postoperative pain scores (NRS), adverse effects related to opioids (allergic reaction, nausea, vomiting).