BACKGROUND: Managing postoperative pain following median sternotomy has long been a notable challenge for anesthesiologists. The administration of postoperative analgesia traditionally relies on intravenous pumps for the delivery of opioids. With the development of regional block techniques and postoperative multimodal analgesia, pecto-intercostal fascial block (PIFB) has gained widespread utilization due to its distinctive advantages. However, its application is limited to a single block. This study aimed to indicate whether continuous PIFB analgesia in cardiac surgery via sternotomy could possess clinical advantages compared with intravenous analgesia in terms of postoperative pain management. If continuous PIFB analgesia was the priority, the secondary objective would involve determining the most effective administration method, making it a critical area of exploration. METHODS: Totally, 114 patients were randomly allocated to three groups: the patient-controlled intravenous analgesia (PCIA) group, receiving intravenous opioid infusion exclusively via pump, and the constant infusion pecto-intercostal fascial block (C-PIFB) and intermittent infusion pecto-intercostal fascial block (I-PIFB) groups, where ultrasound-guided PIFB with a nerve-blocking pump was administered. The C-PIFB group received a constant basal infusion, while programmed intermittent boluses were administered in the I-PIFB group. The primary end point was postoperative visual analog scale (VAS) scores, and secondary outcomes included intraoperative sufentanil consumption, time to extubation, mobilization, length of stay in the intensive care unit (ICU) and hospital, and the incidence of postoperative complications. RESULTS: The VAS scores at rest and during coughing were noticeably diminished in the two block groups relative to the intravenous pump group at 12, 24, 48, and 72 h postoperatively. Notably, intraoperative sufentanil consumption was significantly reduced in the C-PIFB group [3.12 (0.93) µg kg -1 ] and the I-PIFB group [3.42 (0.77) µg kg -1 ] compared with the PCIA group [4.66 (1.02) µg kg -1 , P <
0.001]. Time to extubation, mobilization, length of stay in ICU and hospital, and use of rescue analgesics did not exhibit statistically significant differences among the three groups. However, the postoperative complication rates were markedly lower in the C-PIFB group (42.11%) and I-PIFB group (36.84%) relative to the PCIA group (81.58%, P <
0.001). There were no significant differences between C-PIFB and I-PIFB groups regarding VAS score, secondary outcomes, and postoperative complications. CONCLUSION: Continuous PIFB can provide satisfactory postoperative analgesia while reducing perioperative opioid consumption, diminishing the risk of postoperative complications, and accelerating postoperative recovery for patients undergoing median sternotomy in cardiac surgery. The constant basal infusion method may be the optimal approach for administering continuous PIFB.