Efficacy of liposomal bupivacaine vs bupivacaine hydrochloride in superficial parasternal intercostal plane block for cardiac surgery patients: a randomized clinical trial

Introduction: Effective pain management remains challenging in cardiac surgery. There is a lack of robust evidence on the use of superficial parasternal intercostal plane (SPIP) blocks with liposomal bupivacaine in median sternotomy. We therefore tested the primary hypothesis that bupivacaine liposomes can reduce cumulative opioid consumption in the initial 3 postoperative days. Methods: This single-center, randomized, blinded, active comparator-controlled trial included patients aged 18-65 years undergoing elective cardiac valve surgery with midline sternotomy. Participants were randomized 1:1 to receive a SPIP block with either liposomal bupivacaine (intervention) or bupivacaine hydrochloride (control). The primary outcome was the cumulative opioid consumption over the first 3 postoperative days, analyzed using a log-linear regression model. Secondary outcomes included daily opioid use and pain scores at rest and during coughing, analyzed with repeated-measures mixed-effects linear regression. Results: A total of 129 patients were analyzed (65 in the intervention group and 64 in the control group). Liposomal bupivacaine did not reduce the cumulative opioid consumption over the first 3 postoperative days compared to the control (estimated geometric mean ratio 0.95, 95%CI: 0.90-1.01, P = 0.125). Daily opioid use also did not differ significantly (estimated geometric mean ratio 0.89, 95% CI:0.78-1.01; P = 0.077). However, patients in the liposomal bupivacaine had lower pain scores at resting (1.54 ± 1.3 vs. 2.21 ± 1.2, ratio of means 0.7, 95% CI: 0.58-0.84, P <0.001) and during coughing (3.07 ± 1.29 vs. 3.72 ± 1.19, ratio of means 0.83, 95% CI: 0.75, 0.91, P<0.001). Fewer patients in the intervention group experienced moderate-to-severe pain during coughing (53.85% vs. 78.13%, OR 0.33, 95%CI: 0.15-0.71, P = 0.022) at 48 hours after extubation. Conclusion: Liposomal bupivacaine for SPIP reduced the incidence of moderate to severe coughing pain at 48 hours after extubation in patients undergoing cardiac surgery with sternotomy, suggesting potential benefits for postoperative analgesia.