Combined SPSP and TTP Blocks for Postoperative Analgesia Post-CABG

Ultrasound-Guided Serratus Posterior Superior Plane and Transversus Thoracic Plane Blocks for Postoperative Analgesia After Coronary Artery Bypass Grafting: A Randomized Controlled Trial

The goal of this clinical trial is to learn if combining two ultrasound-guided nerve blocks - one for the front of the chest and one for the side of the chest - works better than standard pain medications alone to treat pain after coronary artery bypass grafting (CABG) surgery. It will also learn about the safety of these nerve blocks. The main questions it aims to answer are:

Does the combined nerve block approach lower the amount of opioid pain medication needed in the first 24 hours after surgery? Does the combined nerve block approach lower pain scores at rest and with movement compared to standard care? What medical problems do participants have when receiving the nerve blocks (such as bleeding, infection, or effects from the local anesthetic)? Researchers will compare the combined nerve block group to a standard care group (no nerve blocks) to see if the blocks improve pain control and recovery after heart surgery.

Participants will:

Be randomly assigned to one of two groups: (1) combined nerve blocks plus standard pain medications, or (2) standard pain medications alone Receive the nerve blocks during surgery while under general anesthesia (if assigned to the block group) Have their pain levels checked regularly using a 0-10 scale for the first 48 hours after surgery Have their breathing, walking time, and opioid medication use monitored during their hospital stay Complete a satisfaction survey about their pain management before leaving the hospital Stay in the hospital for their routine recovery period (typically 5-7 days) with no extra visits required

This is a single-center, patient- and outcome-assessor-blinded, randomized controlled trial conducted at Ain Shams University Hospitals, Cairo, Egypt. Adults aged 18-75 years scheduled for elective isolated CABG via median sternotomy will be enrolled.

Eligible participants will be randomized 1:1 to either:

Intervention group: Bilateral transversus thoracic plane (TTP) block + bilateral serratus posterior superior (SPSP) block with 0.25% bupivacaine (15 mL per side per block, total 60 mL = 150 mg), performed after induction of general anesthesia and before surgical incision, plus standardized multimodal systemic analgesia.

Control group: Standardized multimodal systemic analgesia alone (no nerve blocks).

Both groups will receive identical standardized anesthesia (fentanyl, propofol, atracurium, sevoflurane), intraoperative hemodynamic management, and postoperative analgesia (IV paracetamol 1 g q6h scheduled, IV ketorolac 30 mg q8h for 24h then 15 mg q8h, rescue IV morphine via protocolized algorithm and patient-controlled analgesia).

The primary endpoint is cumulative 24-hour postoperative opioid consumption (IV morphine milligram equivalents) from extubation. Secondary endpoints include NRS pain scores at rest and with movement at 0, 6, 12, 24, and 48 hours; time to first rescue analgesia; time to first ambulation; respiratory outcomes (time to extubation, PaO₂/FiO₂ ratio, pulmonary complications); hemodynamic stability; ICU and hospital length of stay; patient satisfaction (Likert 1-5); and safety outcomes (block-related complications, LAST, opioid-related adverse events).

Sample size: 88 patients (44 per group), calculated for 80% power to detect a 30% reduction in 24-hour opioid consumption (Cohen's d = 0.60) at α = 0.05, with 15% dropout allowance.

Randomization will be computer-generated with permuted blocks (sizes 4 and 6), stratified by on-pump versus off-pump status and sex. Allocation concealment via sequentially numbered opaque sealed envelopes. Blinding: patients, outcome assessors, ICU staff, data collectors, statisticians, and non-performing anesthesiologists/surgeons will be blinded; only the performing anesthesiologist will be unblinded.

A Data and Safety Monitoring Board will review unblinded safety data at 25% and 50% enrollment. Stopping rules: any death attributable to intervention, ≥2 symptomatic pneumothoraces, or ≥2 severe LAST events.

Statistical analysis: ITT as primary population, per-protocol for sensitivity. Primary analysis: ANCOVA adjusting for age, sex, BMI, on-pump status, and intraoperative opioid dose. Missing data handled via multiple imputation (MICE, 20 datasets) with sensitivity analyses.

Inclusion Criteria:

• Adults aged 18-65 years.
• Scheduled for elective, isolated CABG via median sternotomy.
• American Society of Anesthesiologists (ASA) physical status II-III.
• Ability to understand the study procedures, provide written informed consent, and reliably report pain scores using the NRS.

Exclusion Criteria:

• Emergency surgery or pre-operative hemodynamics instability.
• Known allergies or hypersensitivity to local anesthetics, paracetamol, morphine, or any study medication.
• Coagulopathy, uncontrolled bleeding risk, or therapeutic anticoagulation that cannot be safely withheld per institutional guidelines (INR > 1.5; platelets < 100 × 10⁹/L at time of block).
• Local infection or cellulitis at any planned injection site on the anterior or lateral chest wall.
• Pre-existing chronic pain syndrome requiring daily opioid analgesia or known opioid dependence.
• Significant cognitive impairment, severe psychiatric disorder, or inability to reliably use pain scales.
• History of prior thoracic surgery or major chest wall deformity distorting anatomy or limiting the ultrasound window.
• Pregnancy or breastfeeding.
• Any other condition judged by the investigator to represent unacceptable risk or preclude study participation.
• Patient refusal or withdrawal of consent.