Bilateral Pecto-Intercostal Fascial Plane Block for Prevention of Chronic Poststernotomy Pain After CABG

This single-center, prospective, parallel-group, randomized controlled trial will evaluate whether ultrasound-guided bilateral single-shot pecto-intercostal fascial plane block (PIFB), when added to standard multimodal systemic analgesia, reduces the incidence of clinically significant chronic poststernotomy pain in adults undergoing elective isolated coronary artery bypass grafting (CABG) through full median sternotomy. A total of 180 eligible participants will be randomized in a 1:1 ratio to one of two groups. The control group will receive standard general anesthesia and standardized multimodal systemic analgesia. The intervention group will receive the same standard anesthesia and systemic analgesia protocol with the addition of ultrasound-guided bilateral single-shot PIFB after induction of general anesthesia and endotracheal intubation and before surgical incision. Randomization will be performed using a computer-generated sequence with concealed variable block sizes. Allocation concealment will be maintained until eligibility has been confirmed and written informed consent has been obtained. The study will use blinded outcome assessment. The anesthesiologist performing the block and the operating room team cannot be blinded because of the nature of the intervention. However, investigators performing postoperative pain assessments and postoperative day 30 and day 90 follow-up evaluations will remain unaware of group allocation. No sham block or placebo injection will be used; therefore, the study will not be described as double-blind or placebo-controlled. In participants assigned to the PIFB group, the block will be performed under ultrasound guidance by experienced anesthesiologists using a standardized technique. After identification of the target fascial plane between the pectoralis major muscle and the intercostal muscle layer and confirmation of needle position, 15 mL of 0.25% bupivacaine will be administered on each side, for a total volume of 30 mL and a total bupivacaine dose of 75 mg. The total dose will not exceed 2 mg/kg. Ultrasound visualization of local anesthetic spread within the target fascial plane will be confirmed. Apart from administration of PIFB in the intervention group, perioperative management will be standardized between groups. General anesthesia, intraoperative monitoring, systemic analgesia, rescue analgesia, postoperative intensive care management, and routine postoperative care will follow the same institutional protocols in both groups. Rescue analgesia will not be withheld or delayed for study purposes. Postoperative pain intensity will be assessed using an 11-point Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Pain will be assessed separately at rest, during coughing or deep breathing, and during mobilization when clinically feasible. Planned early postoperative assessments will be performed at 6, 12, 24, 48, and 72 hours after surgery and on postoperative day 5, or on the day of discharge if discharge occurs earlier. If a participant is intubated, sedated, delirious, or otherwise unable to communicate reliably at a scheduled assessment time, the pain assessment will not be performed and the reason will be documented. The primary outcome will be the proportion of participants with clinically significant chronic poststernotomy pain on postoperative day 90. Clinically significant chronic poststernotomy pain will be defined as pain that develops after surgery or is aggravated by surgery; is localized to the sternotomy line, parasternal region, chest tube insertion sites, or thoracic wall area related to internal thoracic artery dissection; persists or recurs at 3 months after surgery; has an average intensity of at least 3 on the 0-10 NRS during the preceding 7 days; and is not better explained by sternal wound infection, mediastinitis, sternal instability or nonunion, recurrent myocardial ischemia, malignancy, or another clinical condition. The primary outcome will be assessed by a blinded outcome assessor using a structured interview. Secondary outcomes will include postoperative pain intensity at rest and with coughing, deep breathing, and mobilization; acute postoperative pain burden; intraoperative and postoperative opioid consumption; rescue analgesic requirement and number of rescue analgesic administrations; time to first rescue analgesia; postoperative nausea and vomiting; oversedation; respiratory depression and other opioid-related adverse effects; time to extubation; duration of invasive mechanical ventilation; intensive care unit length of stay; hospital length of stay; and persistent postoperative pain on postoperative day 30. All opioids administered intraoperatively and postoperatively will be recorded by drug, dose, route, and time of administration and converted to morphine milligram equivalents. Postoperative opioid consumption will be evaluated over prespecified periods including 0-24, 0-48, and 0-120 hours. At postoperative day 30, participants will undergo structured assessment for persistent surgery-related thoracic wall pain, including pain location, average and worst pain intensity during the preceding 7 days, relationship to rest and activity, ongoing analgesic use, sleep disturbance, functional limitation, and return to usual activities or work. At postoperative day 90, participants will undergo the primary chronic poststernotomy pain assessment. Additional assessments will include presence of any chronic poststernotomy pain, pain intensity and localization, continuous or intermittent pain pattern, ongoing analgesic use, effects on sleep and daily activities, and neuropathic pain features. In participants reporting pain, neuropathic characteristics will be assessed using the DN4 and S-LANSS instruments specified in the protocol. Participants will be followed from the preoperative assessment through postoperative day 90. The primary analysis will follow the intention-to-treat principle, with participants analyzed according to their original randomized group regardless of treatment crossover, incomplete block performance, protocol deviations, or other post-randomization events. A per-protocol analysis will be performed as a supportive sensitivity analysis.