Additive Regional Fascial Plain Blocks to Pectointercostal Fascial Block for Postoperative Pain Management After Cardiac Surgery: a Randomized Controlled Trial

The ultrasound probe will be positioned parallel and 2-3 cm lateral from the midline in the 4th or 5th intercostal space. The needle will be inserted in-plane in a cauda-cranial direction until the tip of the needle reaches the plane of the fascia between the pectoralis major muscle and the external intercostal muscles. A 20 ml volume of bupivacaine 0.25% will be injected on each side.

After the PIFPB is performed with the same position and probe, a bilateral posterior rectus sheath block (PRSB) will be conducted. The probe will be placed 2-3 cm next to the xiphoid in the epigastric region and parallel to the costal margin. The needle will be inserted into the plane between the rectus abdominal muscle and its posterior sheath. After verifying needle placement, 10 ml of bupivacaine 0.25% will be injected on each side.

After the PIFPB is performed with the same position and probe, an external oblique block will be used to place the linear array ultrasound probe between the midclavicular line and the anterior axillary line at the level of the 6th rib, with the direction mark pointing to the cephalad. The probe will be rotated on the slightly medial cranial end, and the caudal end will be lateral to produce a mesial sagittal oblique view and a short-axis view of the ribs. The following structures will be identified from superficial to deep layers: subcutaneous tissue, external oblique muscle, intercostal muscles, pleura, and lung. After determining the thoracic fascial space between the external oblique muscle and the intercostal muscles, bupivacaine 20 mL will be slowly injected into the space with a nerve block needle at the head side of the 6th rib horizontally near the mid axillary line. The block will be repeated in the same way on the other side.