Determination of the ED 50 of intravenous lidocaine for pain on awakening after pediatric tonsillectomy: A randomized controlled trial

Background: We investigated the potential of intravenous lidocaine to reduce pain on awakening in a dose-dependent manner and aimed to determine the median effective dose (ED ₅₀ ) of lidocaine in 200 children aged 3–12 years (American Society of Anesthesiologists physical status I–II) who underwent elective tonsillectomy with or without adenoidectomy at Yichang Central People’s Hospital. Methods: The patients were randomized into four dose groups (A–D: 0.0, 1.0, 1.5, and 2.0 mg/kg, respectively) and underwent the same anesthetic induction and maintenance protocols. The primary outcome was pain on awakening, whereas secondary outcomes included pain scores at 1, 4, 12, and 24 h after awakening; incidences of laryngospasm, bronchospasm, or perioperative stridor; and time to extubation. Intraoperative cardiac events were classified as safety events. Results: Our findings indicated that intravenous lidocaine dose-dependently reduced pain on awakening. The ED ₅₀ of intravenous lidocaine for pain on awakening was 1.75 mg/kg. Significant differences were observed between groups A and D (P ≤ 0.001). No incidents of laryngospasm, bronchospasm, or perioperative stridor were observed. Furthermore, there were significant between-group differences in time to extubation (P ≤ 0.05). Conclusion: In conclusion, our study demonstrated that lidocaine dose-dependently reduced pain on awakening in children undergoing tonsillectomy with or without adenoidectomy (ED ₅₀ = 1.75 mg/kg), with no severe adverse events. Trial registration: This study was approved by the Institutional Review Board of Yichang Central People’s Hospital (HEC-KYJJ-2020-038-02), The trial was registered at www.chictr.org.cn (ChiCTR2100053006).