Optimizing Analgesia After Minimally Invasive Cardiac Surgery: A Randomized Non-Inferiority Trial Comparing Interpectoral Plane Block Plus Serratus Anterior Plane Block to Erector Spinae Plane Block

Figure 1. Illustration of ultrasound-guided interpectoral plane block. The ultrasound probe is placed over the pectoral region to visualize the pectoralis major and pectoralis minor muscles. A needle is advanced in-plane toward the interfascial plane between these muscles, where local anesthetic is deposited. The pectoral branch of the thoracoacromial artery serves as an anatomical landmark near the target region. The intercostal neurovascular bundles are located just inferior to each rib. PM: pectoralis major muscle; Pm: pectoralis minor muscle; LA: local anesthetic; PTA: pectoral branch of the thoracoacromial artery; ICM: intercostal muscle; r2: second rib; r3: third rib; r4: fourth rib.

Figure 2. Illustration of the ultrasound-guided superficial serratus anterior plane block. The ultrasound probe is positioned to visualize the latissimus dorsi and serratus anterior muscle. A needle is inserted in-plane toward the fascial plane between these two muscles, and local anesthetic is administered. The thoracodorsal artery serves as a key anatomical landmark for correct placement. The intercostal neurovascular bundles are located just inferior to each rib. LDM: latissimus dorsi muscle; SAM: serratus anterior muscle; LA: local anesthetic; TDA: thoracodorsal artery; ICM: intercostal muscle; r3: third rib; r4: fourth rib; r5: fifth rib.

Figure 3. Illustration of ultrasound-guided erector spinae plane block. The ultrasound probe is placed longitudinally over the transverse process. A needle is advanced in-plane into the fascial plane between the erector spinae muscle and the transverse process, where local anesthetic is deposited. The drug spreads cranio-caudally, targeting both the dorsal and ventral rami of the spinal nerves. The pleura is visible beneath the injection site and serves as a critical structure to avoid.

Figure 4. CONSORT flow diagram of participant enrollment. The chart outlines the study process, including the number of patients assessed for eligibility, randomized, allocated to either the ESPB or IPB + SAPB group, followed up, and included in the final analysis. Reasons for exclusion or loss to follow up are provided at each stage, in accordance with CONSORT guidelines. ESPB: erector spinae plane block; IPB: interpectoral plane block; SAPB: superficial serratus anterior plane block.

Figure 5. Changes in pain scores over time following minimally invasive cardiac surgery with ESPB and IPB + SAPB. (A) Box plots representing CPOT scores at 0, 2, 4, and 6 h postoperatively. A significant time effect was observed (p = 0.029), but no group or time × group interaction effect was found. Outlier values at the 6-h time point are represented by diamond symbols. (B) Box plots representing NRS scores at 6, 12, 24, and 48 h postoperatively, recorded during the postoperative period when patients were awake and extubated. No statistically significant differences were detected between the groups. ESPB: erector spinae plane block; IPB: interpectoral plane block; SAPB: superficial serratus anterior plane block; CPOT: critical-care pain observation tool; NRS: numeric rating scale.