Serratus Posterior Superior Intercostal Plane Block Versus Superficial Parasternal Intercostal Plane Block With Local Infiltration for Postoperative Analgesia in Open Cardiac Surgery: A Randomized Controlled Trial

Objectives: Postoperative pain after open cardiac surgery arises from both sternotomy and chest drains and is often inadequately controlled by anatomically limited techniques. This study compared the serratus posterior superior intercostal plane block (SPSIPB, C3-T10 spread) with superficial parasternal intercostal plane block (PSIPB) plus chest drain-site infiltration. Design: Prospective, randomized, controlled trial with blinded outcome assessment. Setting: Single-center tertiary referral cardiac surgery center. Participants: Adults undergoing elective open cardiac surgery via median sternotomy; 80 assessed for eligibility, 76 randomized. Interventions: Bilateral SPSIPB (n = 35) or bilateral PSIPB plus local anesthetic infiltration at mediastinal and pleural chest drain sites (n = 41), performed preoperatively under ultrasound guidance. Measurements and Main Results: The primary outcome was cumulative 24-hour opioid consumption (morphine milligram equivalents, MME); the registered secondary outcomes were Numerical Rating Scale (NRS) pain scores at rest and on coughing and the Quality of Recovery–15 (QoR-15) at 24 hours. All other comparisons were exploratory. Twelve patients were excluded after randomization (2 SPSIPB, 10 control), leaving 33 and 31 for analysis. Opioid consumption was significantly lower in the SPSIPB group (36.6 ± 17.5 v 56.7 ± 16.1 mg of MME; mean difference 20.1 mg of MME; 95% CI, 11.7-28.5; p < 0.001). NRS scores were comparable during the first postoperative hour but lower in the SPSIPB group from 2 hours onward during coughing and at 4, 8, and 24 hours at rest (all p ≤ 0.019). QoR-15 scores were higher in the SPSIPB group (119 [112-126] v 108 [105-111.5]; median difference 10 points; 95% CI, 6-15; p < 0.001), exceeding the minimal clinically important difference of 6 points. Adverse events, including postoperative nausea and vomiting, did not differ between the groups. Conclusions: Compared with PSIPB plus drain-site infiltration—an active comparator targeting both the sternal and drain regions—SPSIPB reduced opioid consumption and improved quality of recovery and may be a valuable component of multimodal analgesia within Enhanced Recovery After Cardiac Surgery (ERACS) protocols.