Dexamedatomidine vs. Dexamethasone in Rhomboidal Intercostal Plain Block and Subserratus Block in Breast Surgery

Rhomboid intercostal block (RIB); a new interfascial plane block involves the triangle of auscultation that's bounded medially by inferior a part of the trapezius, inferiorly by the superior border of latissimus dorsi, and laterally by the medial border of the scapula. The local anaesthetic spreads between the rhomboid major and therefore the intercostal fascia at the extent of T6-T7 and provides analgesia of T3-T8 dermatomes. Aiming to expand dermatomal coverage, a new modification of Rhomboid Intercostal and Sub-Serratus block (RISS) is performed by advancing the ultrasound probe caudally and laterally distal to the inferior angle of the scapula, the second injection apply between the serratus and intercostal muscle fascia. The RISS block is a novel ultrasound-guided block that has been shown to provide analgesia from T2-T11 dermatomes. Dexmedetomidine is a potent selective α 2 adrenoceptor agonist that was reported in many previous studies as an adjunct to regional and general anesthesia, with significant prolongation of the duration of sensory block, motor block and analgesia, and accelerate the time to onset of sensory and motor block when added to a local anesthetic. Dexamethasone is a potent long-acting steroid that has shown efficacy as an adjuvant to local anesthetics in various studies. It enhances peripheral nerve blocks when added to local anesthetics, providing better quality of anesthesia as well as postoperative analgesia. The mechanism by which dexamethasone prolong the duration of local anesthetics are not completely understood; however, some studies demonstrated that dexamethasone exerts its action through reducing the release of inflammatory mediators and by inhibiting discharge of C-fibers.