Optimal ropivacaine concentration for ultrasound-guided erector spinae plane block in patients who underwent video-assisted thoracoscopic lobectomy surgery

Background: An ultrasound-guided erector spinae plane block (ESPB) has emerged as an effective way to control postoperative pain and may be a good alternative way to an epidural block. However, relevant research on the appropriate concentration of local anesthetics for an ESPB remains scarce. Aims: This study aimed to investigate the optimal concentration of ropivacaine for an ESPB in patients undergoing video-assisted thoracoscopic surgery (VATS). Methods: A total of 68 patients who underwent a VATS lobectomy were enrolled. An ipsilateral ultrasound-guided ESPB was performed with three different ropivacaine concentrations as a local anesthetic: 0.189% (G1), 0.375% (G2), and 0.556% (G3). The total amount of perioperative remifentanil administered, patient-controlled analgesia (PCA) applied, and rescue drugs for postoperative analgesia during the 24 h after surgery were acquired, and numeric rating scale (NRS) scores were obtained. Results: The total amount of intraoperative remifentanil administered was 7.20 ± 3.04 mcg/kg, 5.32 ± 2.70 mcg/kg, and 4.60 ± 1.75 in the G1, G2, and G3 groups, respectively. G2 and G3 had significantly lower amounts of remifentanil administered than the G1 group (P = 0.02 vs. G2; P = 0.003 vs. G3). The G3 group needed more inotropes than the G1 and G2 groups in the perioperative period (P = 0.045). The NRS scores, PCA, and rescue drug were not significantly different in the three groups. Conclusion: The optimal concentration of ropivacaine recommended for an ESPB was 0.375%, which was effective in controlling pain and reducing the intraoperative opioid requirements with minimal adverse reactions such as hypotension.