Ultrasound-Guided Subtransverse Interligamentary Plane Block Versus Thoracic Paravertebral Block for Quality of Recovery After Modified Radical Mastectomy: A Randomized Non-Inferiority Trial

Breast carcinoma is a common malignancy in females, with modified radical mastectomy (MRM) being the most frequently performed surgery. Surgical intervention is accompanied by significant challenges such as postoperative pain and stress, potentially leading to prolonged hospitalizations and complications. Previous studies had demonstrated that thoracic paravertebral block (TPVB) was effective in diminishing opioid requirements for patients undergoing breast surgery. TPVB is technically challenging, requiring skilled healthcare professionals and the narrow paravertebral space, located between the superior costotransverse ligament (SCTL) and the parietal pleura, poses a risk of inadvertent pleural puncture and vascular damage, and increased the potential for pneumothorax and haematoma. The Subtransverse process Interligamentary (STIL) plane block is a recently introduced technique that holds promise as an alternative to TPVB. STIL plane block specifically targets the region adjacent to the paravertebral space, rather than directly penetrating it, which theoretically diminishes the potential risks of inadvertent pneumothorax and hematoma compared with TPVB. Additionally, due to its close anatomical proximity to the paravertebral space, the STIL plane block may facilitate a more straightforward dispersion of local anaesthetics into this area. Research has also confirmed that the block achieved with STIL plane block is effective in providing adequate pain relief for breast surgeries. Also it was associated with decreased postoperative opioid consumption compared to the ESP block in patients undergoing MRM. With the improvement of anaesthesia technology, the quality of patient recovery is no longer solely measured by the success of the surgery or the discharge rate, but is increasingly oriented towards a "patient-centered" approach that focuses on the safety, comfort, and overall quality of recovery throughout the perioperative period. In light of the growing emphasis on improving postoperative quality of recovery while ensuring patient safety, we hypothesize that the STIL plane block will demonstrate non-inferiority to the thoracic PVB in terms of postoperative quality of recovery and analgesia in patients undergoing MRM.