The effect of sub-Tenon lidocaine injection on emergence agitation after general anaesthesia in paediatric strabismus surgery

Sevoflurane is widely used for paediatric anaesthesia. However, many cases of emergence agitation after sevoflurane anaesthesia have been reported and pain was suggested as a major contributing factor. The purpose of this study was to evaluate the effect of sub-Tenon lidocaine injection on emergence agitation in children receiving sevoflurane or propofol-remifentanil anaesthesia.We enrolled 260 children, aged 4-10 years, who were scheduled for strabismus surgery, and randomized them to one of four groups: group SS, SL, BS, and BL. Anaesthesia was maintained with sevoflurane (SS, SL) or propofol-remifentanil infusion (BS, BL). At the end of surgery, the surgeon injected into the sub-Tenon space 1 ml of isotonic saline (SS, BS) or 2% lidocaine (SL, BL). Emergence behaviour was assessed in the post-anaesthesia care unit using a 5-point scoring scale (score 1, asleep; 2, awake and calm; 3, irritable or consolable crying; 4, inconsolable crying; and 5, severe restlessness). We defined a score of 4 or 5 as emergence agitation. The incidence of emergence agitation was analysed using χ² and Fisher's exact test.The incidence of emergence agitation in group SL and BL was significantly lower compared to group SS and BS, respectively (P = 0.011, 0.019). The lidocaine-injected group showed significantly lower occurrence of emergence agitation (10.4%) than isotonic saline-injected group (27.2%; P = 0.001). Emergence agitation was significantly higher following sevoflurane (25.0%) than balanced anaesthesia (13.1%; P = 0.023).The frequency of emergence agitation is significantly reduced by sub-Tenon lidocaine injection regardless of the modality of anaesthesia used.