Postoperative Analgesia in Patients Undergoing Open Upper Abdominal Surgeries: External Oblique Intercostal Plane Block vs. Quadratus Lumborum Block

The patient will be placed in the supine position. After sterilization of the skin, a high-frequency linear probe (6-13 MHz) will be placed obliquely medial to the anterior axillary line, the 6th and 7th ribs, skin, subcutaneous tissues, and external oblique muscle \[EOM\], intercostal muscles, pleura, and the lung will be identified. An 80 mm 22-gauge block needle (Stimuplex® D, BBraun, Germany) will be inserted in-plane to the US-probe in a craniocaudal direction directed under EOM. After confirmation of negative blood aspiration, 2-3 mL of normal saline will be injected for hydro-dissection to verify the correct needle tip placement then 30 mL of 0.25% bupivacaine will be injected between the EOM and intercostal muscles

Quadratus lumborum block will be performed. The patient will be placed in the lateral decubitus position After sterilization of the skin, a low frequency convex probe (5-8 MHz) will be positioned horizontally in the anterior axillary line half way between the subcostal margin and the iliac crest then will be advanced in the cranial direction to visualize the triple abdominal muscle layers and identifying the posterior border of the EO muscle (hook sign) with the underlying IO musclenforming a roof over the QL muscle. The QL muscle could be visualized with its attachment to the lateral edge of the transverse process of the L4 vertebral body. An 80 mm 22-gauge block needle will be inserted in-plane to the US-probe in an anterolateral to posteromedial direction. The needle tip will be placed between the middle layer of the thoracolumbar fascia and the QL muscle. After confirmation of negative blood aspiration, 30 mL of 0.25% bupivacaine will be injected.

A single injection of 30 mg of 0.25 % bupivacaine will be administered as part of the External Oblique Intercostal Plain Block under ultrasound guidance, after confirming needle placement between the external oblique and intercostal muscles.

A single injection of 30 mg of 0.25 % bupivacaine will be administered as part of the Quadratus Lumborum Block under ultrasound guidance, after confirming of correct needle placement and negative aspiration.