The Effect of Superficial Parasternal Intercostal Plane Catheter Analgesia Following Sternotomy in Coronary Artery Bypass Surgery on Postoperative Pain: A Prospective Randomized Controlled Trial

Patients undergoing coronary artery bypass surgery will be included. Patients will be divided into two groups: the block group, in which a bilateral superficial parasternal plexus catheter will be inserted, and the control group, in which no parasternal plexus block or catheter will be administered.

In the block group, the catheter placement will be performed after completion of the surgery and before the patient is transferred to the ICU, under ultrasound guidance (Venue Go, GE, L4-T12 high-frequency linear probe). The probe will be positioned transversely across the costal cartilage, parallel to the sternum, in a parasagittal orientation at the level of 3rd rib. A 5-cm Tuohy needle will be inserted 2 cm lateral to the midline and advanced between the pectoralis major and external intercostal muscles at the third parasternal intercostal space. Needle tip position will be confirmed by negative aspiration for blood or air, followed by injection of 20 mL of bupivacaine 0.2% into the parasternal plane. Correct needle position will be confirmed by visualization of local anesthetic spread and hydrodissection separating the pectoralis major from the ribs and external intercostal muscles. A catheter (Tuohy Ultra-360 18G, B. Braun Contiplex, 400 mm) will then be placed into the parasternal intercostal space. Catheter position will be confirmed by ultrasound visualization of spread of 10 mL saline, after which the catheter will be secured. The procedure will be performed bilaterally. Postoperatively, 20 mL of bupivacaine 0.2% will be administered by the clinician through each parasternal catheter at 12, 24, 36, 48, 60, and 72 hours. Catheters will be removed by the clinician at 72 hours. Catheter-related complications, including bleeding, infection, and dislocation, will be recorded.

In the control group, no parasternal plexus block or catheter will be placed.

Intraoperative anesthesia technique will be identical in both groups. All patients will be admitted to the ICU orotracheally intubated and will be extubated in the ICU rather than in the operating room.

Pain nurses will assess all patients every 12 hours for 72 hours postoperatively. At each visit, pain score will be recorded using the Visual Analog Scale, where 0 corresponds to no pain and 10 corresponds to worst pain, assessed both at rest and during movement. Postoperative opioid consumption will be monitored via a patient-controlled analgesia device. The Morphine PCA solution will be prepared at a concentration of 1 mg/mL, with no background infusion, a bolus dose of 1 mL, and a lockout interval of 15 minutes. Additional (rescue) opioid analgesic requirements will be recorded by pain monitoring nurses. Rescue analgesia in both groups will consist of tramadol 1 mg/kg administered intravenously.