Analgesic Effects and Pharmacokinetics of Ropivacaine at Different Concentrations in Serratus Anterior Plane Block in Patients Undergoing Video-Assisted Thoracoscopic Surgery: A Prospective Randomized Trial.

Abstract

Purpose: Investigate the analgesia effects and pharmacokinetics of ropivacaine at different concentrations in Serratus Anterior Plane Block (SAPB) and assess the efficacy and safety.

Methods: Thirty-six patients undergoing video-assisted thoracoscopic surgery (VATS) pulmonary resections were enrolled. Ultrasound-guided SAPB was induced with 3 mg/kg ropivacaine at different concentrations (0.25%, 0.5%, and 0.75%, referred to as Group L, Group M, and Group H, respectively). The concentration of ropivacaine in the plasma at 1, 15, 30, 45, 60 min, 2, 4, 8, 12, and 24 h after SAPB was determined by LC-MS/MS. Other evaluated measures included the Numerical Rating Scale (NRS) scores at rest and on movement, the frequency of dermatomes blocked, onset time and effective plane, Quality of Requirements(QoR)-15 scale, chronic postsurgical pain, and the level of IL-6 and IL-8.

Findings: The NRS scores were significantly higher in Group L than those in other groups (P < 0.05), indicating that the analgesic effect of Group L was the worst among the three groups. Group H had a lower effective plane of anesthesia and significantly higher incidence of chronic postsurgical pain. The IL-8 level was significantly lower in Group H than in other groups at 1 min, 1 h, and 24 h after SAPB. The ropivacaine concentrations were the highest in Group H, followed by Group M and Group L. The high blood concentration of ropivacaine in Group H may increase the risk of systemic toxicity from local anesthetics. Compared to Group L and Group H, Group M had superior analgesic effects and better safety. Among the three groups, C_max, t_1/2, and AUC_0-∞ differed significantly.

Implications: For patients undergoing VATS, using 0.5% ropivacaine for SAPB is recommended.