Comparison of the preventive effects of pretreatment of lidocaine with a tourniquet and a premixed injection of lidocaine on propofol-LCT/MCT injection pain

BACKGROUND: Lidocaine has been used widely to prevent propofol injection pain. Various methods of administration exist, such as lidocaine premixed with propofol or lidocaine pretreatment using a tourniquet, but it is unclear which method of lidocaine administration is more effective for the prevention of injection pain of propofol LCT/MCT. The purpose of this study was to compare pretreatment of lidocaine with a tourniquet and a premixed injection of lidocaine to prevent injection pain of propofol-LCT/MCT. METHODS: Patients were randomly allocated into the pretreatment group (n = 117) or the premixed group (n = 117). The pretreatment group was pretreated with 2 ml of lidocaine 2%, held with a tourniquet, before propofol-LCT/MCT injection. The premixed group was injected with a premixed solution of propofol-LCT/MCT and 2 ml of lidocaine 2%. To evaluate the incidence and severity of pain, spontaneous verbal expressions of pain, movement of hand, frowning, and moaning were recorded, and the patients were asked to recall their pain with the visual analogue score (VAS) 30 minutes after awakening from anesthesia. RESULTS: Overall, injection pain occurred in 13.7% of the pretreatment group and 15.4% of the premixed group, without any statistical difference (P = 0.71). There was no difference in spontaneous verbal expressions of pain, movement of hand, frowning, and moaning between the two groups. The pain intensity (VAS) also showed no difference between the two groups (P = 0.49). CONCLUSIONS: Pretreatment of lidocaine with a tourniquet showed no more benefit to prevent injection pain of propofol LCT/MCT compared to a premixed injection with lidocaine.