Superficial parasternal intercostal plane blocks with liposomal bupivacaine did not significantly reduce opioid use after cardiac surgery: a randomized clinical trial.

Background: Acute pain after cardiac surgery via median sternotomy is commonly managed with multimodal analgesia, but optimal regional techniques remain uncertain. Superficial parasternal intercostal plane (SPIP) blocks have shown promise for postoperative pain control, with the use of catheters extending these benefits up to three days. This study evaluated the efficacy of single-injection SPIP blocks with liposomal bupivacaine in reducing opioid consumption following cardiac surgery.

Methods: In this prospective, randomized, double-blind controlled trial, 100 patients undergoing elective coronary artery bypass grafting or valve surgery via median sternotomy were randomized to receive bilateral SPIP blocks with either a mixture of bupivacaine and liposomal bupivacaine or saline placebo prior to incision. The primary outcome was total opioid consumption in oral morphine milligram equivalents (MME) over the first 72 postoperative hours. Secondary outcomes included pain scores, time to extubation, intensive care unit (ICU) and hospital length of stay and opioid use at 90 days.

Results: Total opioid consumption in the first 72 hours was not significantly different between groups (SPIP intervention: 165 (IQR 103-284) MME vs saline placebo: 205 (IQR 145-282) MME, p=0.30). Pain scores, extubation time, ICU and hospital length of stay, and opioid use at 90 days were also similar between groups. No serious adverse events were reported.

Conclusions: Preincision bilateral SPIP blocks with a mixture of bupivacaine and liposomal bupivacaine did not significantly reduce opioid consumption or improve postoperative analgesic outcomes compared with saline placebo in cardiac surgical patients. These findings suggest that single-injection SPIP blocks with liposomal bupivacaine may not be as effective as repeated injections or catheters in cardiac surgical patients. Further studies should explore modifications to block techniques such as multilevel injections, the timing of the block relative to surgery, alternative local anesthetics, and strategies specifically targeting chest tube-related pain.

Trial registration number: NCT04928339.