Serratus Anterior Plane and PECS II Blocks After Coronary Artery Bypass Grafting

This prospective, randomized, placebo-controlled trial evaluated the postoperative analgesic efficacy of ultrasound-guided bilateral serratus anterior plane (SAP) block and bilateral PECS II block in adult patients undergoing elective coronary artery bypass grafting (CABG). Participants were randomly assigned to one of three groups: bilateral SAP block, bilateral PECS II block, or bilateral sham fascial plane injections (placebo comparator). All participants received the same standardized postoperative systemic analgesic regimen.

To preserve allocation concealment and blinding, an investigator not involved in patient management prepared identical coded syringes according to the randomization sequence. The physician performing the ultrasound-guided procedures was unaware of syringe contents. All participants underwent bilateral injections at both the PECS II and SAP fascial planes; depending on group allocation, each fascial plane received either 0.25% bupivacaine or 0.9% saline. Postoperative outcome assessment was performed by investigators blinded to treatment allocation.

The primary outcome was postoperative pain intensity measured using the Visual Analog Scale (VAS) at predefined time points after extubation. Secondary outcomes included cumulative opioid consumption during the first 24 postoperative hours, postoperative nausea and vomiting (PONV), and block-related complications. Additional recovery-related outcomes included duration of mechanical ventilation, time to first mobilization, and intensive care unit (ICU) length of stay. These recovery outcomes were analyzed as exploratory endpoints because ICU clinicians were not blinded and important perioperative factors influencing recovery were not systematically collected.

Inclusion criteria

Adults aged 20 years and older ASA physical status II-IV Scheduled for elective coronary artery bypass grafting (CABG) via median sternotomy Extubated in the intensive care unit after surgery Provided written informed consent

Exclusion criteria

Refusal to participate or inability to provide informed consent Pregnancy Known allergy or contraindication to bupivacaine or other amide local anesthetics Coagulopathy or ongoing anticoagulation precluding regional anesthesia Local infection at the planned injection site Severe hepatic or renal failure Pre-existing chronic opioid use or chronic pain requiring opioid treatment Pre-existing neurological disorders affecting pain assessment Requirement for emergency surgery or concomitant cardiac procedures other than isolated CABG Reoperation for postoperative bleeding before outcome assessment