Optimal timing of parasternal intercostal nerve block application (pre-incisional versus post-incisional) for acute pain management in cardiac surgery; a randomized double-blinded clinical trial

Background
In patients undergoing cardiac operations, parasternal intercostal nerve block (PSIB) has been suggested to enhance pain management and lower opioids consumption. However, inadequate literature has discussed its effectiveness as a pre-emptive analgesic approach. This trial was designed to investigate the optimal timing to perform the block pre- or post-surgical incision.
Methods
This prospective study enrolled 51 patients, aged 18–70 years, with ASA status II/III, who underwent on-pump cardiac surgery. Participants were allocated to two groups randomly; Group-A received ultrasound-guided PSIB pre-incisional, while in Group-B, the surgeon performed the block under direct vision. Ten bilateral injections of four milliliters each containing bupivacaine (0.25%) were given (40 ml total volume). The study primary outcome was the amount of morphine consumed within postoperative 24 h. The secondary measures included fentanyl utilization and hemodynamic swings during surgery, as well as postoperative pain scores, rescue analgesic doses, adverse events, extubation time, ICU and hospital stay durations, and patients’ satisfaction.
Results
The pre-incisional PSIB demonstrated significant decrease in intraoperative fentanyl utilization (893.85±113.39 ug vs. 982±129.81 ug, =0.01) and more stabilization of hemodynamics at skin incision and sternal retraction time-points, compared to postincisional group. Otherwise, no significant differences were noted regarding the total postoperative morphine consumption (28.54±17.17 mg vs. 27.92±15.52 mg), pain scores, rescue analgesic demand, extubation time, length of ICU stay, hospitalization duration in both groups.
Conclusion
Pre-incisional and post-incisional PSIB presented comparable pain profile in the early postoperative period after open heart surgeries. But pre-emptive application of PSIB showed better control of intraoperative hemodynamics and less fentanyl utilization.