A Single-blind, Randomized Controlled Trial Comparing Postoperative Analgesic Effects of Superficial and Deep Parasternal Intercostals Blocks in Patients Undergoing Coronary Artery Bypass Grafting Surgery.

Abstract

Objective: To compare the analgesic efficacy of anesthesiologist-performed ultrasound-guided superficial parasternal intercostal plane block (SPIPB) and surgeon-performed deep parasternal intercostal plane block (DPIPB) in patients undergoing coronary artery bypass grafting (CABG) via median sternotomy.

Design: A prospective, randomized, single-blind clinical trial.

Setting: A single, tertiary care university hospital.

Participants: Seventy-five participants (aged 45-80 years, ASA III-IV) scheduled for elective isolated CABG surgery.

Interventions: Participants were randomly assigned to the SPIPB, DPIPB, or control groups. Regional blocks were performed either under ultrasound guidance after sternal closure and sterilization of the surgical site (SPIPB) or intraoperatively under direct vision (DPIPB). Postoperative pain was managed with multimodal analgesia protocols.

Measurements and main results: Outcomes included pain scores and tramadol administration at the 1st, 4th, 12th, and 24th postoperative hours, as well as after extubation. The cumulative 24-hour tramadol administration (primary outcome) was significantly lower in the DPIPB group (95 ± 44 mg) compared with the SPIPB (141 ± 58 mg) and control groups (176 ± 61 mg) (p < 0.001). Compared with the control group, the DPIPB group had a significantly reduced likelihood of requiring high-dose tramadol (odds ratio [OR]: 0.18, 95% confidence interval [CI]: 0.06-0.56, p = 0.003). The SPIPB group showed an intermediate effect compared with control (OR: 0.52, 95% CI: 0.23-1.18, p = 0.095). When directly compared, DPIPB was associated with significantly lower tramadol use than SPIPB (OR: 0.34, 95% CI: 0.16-0.72, p < 0.001). Pain scores at all time points were significantly lower in both block groups compared with control (p < 0.05), with DPIPB showing the most pronounced effect. No block-related complications were observed.

Conclusions: Both parasternal intercostal blocks improved postoperative analgesia compared with standard care. The SPIPB was performed under ultrasound guidance, whereas the DPIPB was applied under direct vision by the surgeon. The DPIPB demonstrated superior opioid-sparing effects and improved dynamic pain control. These findings support the use of parasternal fascial plane blocks, whether performed under ultrasound guidance or direct vision, as effective components of multimodal analgesia in cardiac surgery.