50% efficacy dose of intravenous lidocaine in supressing sufentanil-induced cough in children: a randomised controlled trial.

Background: Opioids such as sufentanil are used as anaesthetics due to their rapid action and superior analgesic effect. However, sufentanil induces a huge cough in paediatric patients. In contrast, intravenous (IV) lidocaine suppresses opioid-induced cough in children, but its use is limited due to anaesthetists' concern about its toxicity. Therefore, this study aimed to evaluate the effect of dose-dependent IV lidocaine on sufentanil-induced cough (SIC) in paediatric patients.

Methods: A total of 188 patients aged 3-12 years scheduled for elective tonsillectomy with or without adenoidectomy were enrolled and divided into four groups depending on different dose of lidocaine: A (0 mg.kg-1), B (1 mg.kg-1), C (1.5 mg.kg-1), and D (2 mg.kg-1). The primary outcome was the SIC grade observed during the induction of general anaesthesia. The secondary outcomes were the incidence of SIC, mean arterial pressure, and heart rate at T0, T1, T2, T3, T4, and T5.

Results: The SIC grade was significantly different between groups A and D (P = 0.04) and between groups B and D (P = 0.03). Moreover, the incidence of SIC in groups A, B, C, and D was 81%, 87%, 68%, and 64%, respectively, and the difference between groups B and C (P = 0.03) and between groups B and D (P = 0.0083) was statistically significant. No statistical differences were observed in the hemodynamic parameters between the groups. The incidence of severe cough was statistically different between group D and group A (P < 0.0001), between group D and group B (P < 0.0001), and between group D and group C (P < 0.0001) respectively.

Conclusions: Lidocaine suppresses SIC in a dose-dependent manner without severe adverse events. IV lidocaine can be used in paediatric patients safely and efficiently, and the median effective dose was 1.75 mg/kg.

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).