Comparison of analgesic efficacy between ultrasound guided Rhomboid Intercostal Sub-Serratus Block and Erector Spinae Plane Block for Postoperative pain in Modified Radical Mastectomy

One day prior to the scheduled surgery, all the patients will be instructed on how to evaluate their own pain by using a 10-cm visual analog pain scale (0=no pain, 10= maximum pain imaginable). After an 8 h fast, the patients will be taken into the operation theatre, where an 18-gauge intravenous (IV) cannula will be secured and all ASA standard monitors will be applied. Before induction the patients will be placed in a lateral decubitus position and one of the two regional blocks will be performed. RISS Block: Patients will be placed in lateral decubitus position with the operating side lying superiorly. The ipsilateral arm was abducted from chest to move scapula laterally, a linear ultrasound probe was placed in sagittal plane at T5-6 level, just medial to scapula, to identify the trapezius, rhomboid major, and intercostal muscles. A 21-gauge needle was inserted in the plane between the rhomboid major and intercostal muscles in a cephalad to caudad direction, and Half dose of 0.6ml/kg of .375% ropivacaine was injected. Thereafter, the ultrasound probe was moved caudally and laterally to identify the tissue plane between serratus anterior and external intercostal muscles for the sub-serratus block at the T8-9 level. The needle was advanced from its previous position, and an remaining half of 0.6ml/kg of 0.375% ropivacaine was injected. ESP Block: Patients will be placed in lateral decubitus position with the operation site up, the vertebrae will be counted from cephalad to caudal direction until reaching T5 spinous process. The ultrasound probe will be placed vertically 3 cm lateral to the T5 spinous process. The transverse process has a square form contour as compared to rib which is rounded form contour. Three muscles will be identified superficial to the hyperechoic transverse process shadow as follows: trapezius, rhomboid major, and erector spinae. Under complete aseptic precautions, the needle will be introduced from superior to inferior direction in-plane until the tip lay deep to erector spinae muscle. 0.5-1 mL of non- active fluid will be injected to confirm correct needle tip position by visualizing spread under erector spinae muscle and after confirming a total of 0.6ml/kg of 0.375% Ropivacaine will be injected. After the block is performed the patients will be positioned supine again. General anaesthesia will be induced with intravenous (IV) Inj. midazolam 25-50 mcg/kg, Inj. fentanyl 1-2 mcg/kg and inj. propofol 1-2.5 mg/kg and intubation will be done after administering inj. vecuronium bromide 0.1 mg/kg IV for muscle relaxation. The lungs will be ventilated to maintain an end-tidal carbon dioxide of 30-35 mmHg. Anaesthesia will be maintained with oxygen and isoflurane (1-2 MAC). At the end of surgery, inj. ondansetron 0.1mg/kg will be given and muscle relaxation will be reversed with inj. neostigmine 50 mcg/kg and inj. glycopyrrolate 10 mcg/kg. The trachea will be extubated and the patients will be transferred to post-anaesthetic care unit. For rescue analgesia (when the VAS score will be ≥ 4) in postoperative period, injection tramadol 100 mg will be given. The duration of analgesia will be the time from administration of block to the first use of rescue analgesic. The obtained data will be recorded and the results will be statistically analyzed by appropriate statistical method.A p value of 0.05 will be considered as significant