Effects of Ropivacaine Concentration on Analgesia After Ultrasound-Guided Serratus Anterior Plane Block: A Randomized Double-Blind Trial

Abstract

Purpose

Serratus anterior plane (SAP) block is effective for analgesia after breast surgery. Whether a higher local anesthetic concentration prolongs sensory block duration and improves postoperative analgesia remains unclear. The aim of this study was to compare the analgesic effects of SAP block with different concentrations of ropivacaine.

Patients and Methods

Sixty patients scheduled for breast surgery were enrolled in this randomized double-blind trial. SAP block was induced with 20 mL of 0.375%, 0.5%, or 0.75% ropivacaine in Group R0.375, Group R0.5, and Group R0.75, respectively. The primary endpoint was the area under the curve (AUC) of numerical rating scale (NRS) pain intensity scores at rest over time. The secondary endpoints were AUC of NRS pain intensity scores on movement over time, active sensory block duration, tramadol consumption, and the elapsed time between completion of surgery and the first administration of rescue analgesia.

Results

The AUC of NRS pain intensity scores at rest of Group R0.375 was significantly higher than that of Groups R0.5 and R0.75 (P=0.025, and P=0.001). The AUC of NRS pain intensity scores on movement of Group R0.375 was also significantly higher than that of Groups R0.5 and R0.75 (both P<0.001). At higher ropivacaine concentrations, the duration of SAP sensory block increased (P<0.001). Tramadol consumption and the elapsed time between completion of surgery and the first administration of rescue analgesia were similar in the three groups (P>0.05).

Conclusion

A comparison of 0.5% and 0.75% ropivacaine showed no significant difference in postoperative analgesia, but both were superior to 0.375% ropivacaine, although higher ropivacaine concentration lengthened the duration of SAP block. Therefore, SAP block with 0.5% ropivacaine is recommended for postoperative analgesia in breast surgery.

Keywords:

• analgesia
• ultrasound
• regional anesthesia
• breast

Abbreviations

ASA, American Society of Anesthesiologists; AUC, area under the curve; BMI, body mass index; LAs, local anesthetics; NRS, numerical rating scale; SAP, serratus anterior plane.

Ethical Statement

The authors declare that all patients gave written informed consent before initiation of the study protocol and was conducted in accordance with the Declaration of Helsinki. The study was approved by the Ethics Committee of The First Affiliated Hospital of Wenzhou Medical University (No. 12, 2018).

Data Sharing Statement

One of the corresponding authors ([email protected]) will be ready to send all related data for any authority on request by an email message. The data will be available this way for up to 6 months after the paper is published.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China (Grant No. 81900231, Beijing, China), and by Wenzhou Science and Technology Bureau (Y20190519, Wenzhou, China).