Role of Parasternal Bupivacaine Injection for Pain Management and Early Extubation in Coronary Artery Bypass Grafting: A Prospective Randomized Placebo-Controlled Study

Background: After cardiac surgery, patients often experience significant pain, primarily due to the median sternotomy or thoracotomy. This pain is usually severe during the first 48 hours, which is the typical duration of their stay in the ICU. Managing this pain effectively is important because it plays a key role in enabling early extubation—usually within 6 to 8 hours after surgery. This approach has become a major advancement in the postoperative ventilatory care of open-heart surgery patients. By optimizing pain control, we can help facilitate early extubation, leading to faster recovery times, decreased length of ICU stay, and better overall outcomes.

Objectives: This study was designed to determine the efficacy of the parasternal injection of Bupivacaine on postoperative pain for early extubation in patients undergoing coronary artery bypass grafting (CABG).

Materials and Methods: Patients admitted for elective primary coronary artery bypass surgery were enrolled in the study. A total of 35 patients were randomized into two groups: Group 1 (Bupivacaine) with 13 patients (37.14%) and Group 2 (Placebo) with 15 patients (42.85%). Standard anesthetic protocols were followed. Bupivacaine 0.5% at 2 mg per kg was diluted in a 50 ml syringe with normal saline, and 50 ml of normal saline was used as a placebo. Identical syringes marked with patient study numbers were delivered to the operating theaters. Both the surgeon and the anesthetist were blinded to the content of the solution. The injection was infiltrated into the parasternal wound at the end of the procedure before placing the sternal wires. The anesthetist assessed patients in the intensive care unit (ICU) for early extubation. Pain intensity was measured using a Visual Analogue Scale (VAS) at the time of extubation.

Results: A total of 35 patients were selected for the study, but only 28 completed it. Seven patients were dropped out due to prolonged ventilation (5 patients) and reopening (2 patients). The mean VAS was 1.38±1.19 in the Bupivacaine group and 6.13±2.92 in the Placebo group, with a significant difference (P<0.001). No rescue pain medication was required in the Bupivacaine group, while 8 patients (53.3%) in the Placebo group required it. The mean ventilation time was significantly shorter in the Bupivacaine group (5.8±1.3 hours) compared to the Placebo group (122±2.8 hours) (P=0.002). Mean partial oxygen pressure was significantly higher in the Bupivacaine group (208.23±42.57) compared to the Placebo group (126.40±23.15) (P<0.001).

Conclusion: Parasternal wound infiltration of long-acting local anesthetic Bupivacaine is an effective method of pain control after sternotomy. It facilitates early extubation with significant improvements in oxygenation and VAS scores.

Larger trials including all categories of open-heart surgery, with more variables such as partial pressure oxygen and carbon dioxide levels and their mean differences, would lead to yield improved and more reliable results.