Effect of alkalinisation of lignocaine for propofol injection pain: a prospective, randomised, double-blind study

The aim of this study was to determine whether pretreatment with alkalinised lignocaine reduced the incidence and severity of pain during propofol injection. This prospective, randomised, double-blind study included 300 adult, American Society of Anesthesiologists physcial status I to II patients undergoing elective surgery. Patients were randomly allocated to one of three groups: Group L received 0.05 ml/kg of 1% lignocaine (5 ml normal saline + 5 ml 2% lignocaine), Group A received 0.05 ml/kg alkalinised lignocaine (5 ml 2% lignocaine + 1 ml 8.4% NaHCO3 + 4 ml normal saline), and Group S, the control group, was given the same amount of normal saline (NaCl 0.9%). All drugs were given as a bolus over 20 seconds before propofol administration. A blinded researcher assessed the patient's pain level using a four-point scale. The pain score [median (range)] and the incidence of pain in Group A (6%) was significantly lower than in groups L (41%) and S (88%, P <0.001). In addition, the pain score and the incidence of pain were found to be significantly different between Group L and Group S (P <0.001). The incidence of moderate and severe pain were greater in Group S when compared with groups A and L (P <0.001). Intravenous pretreatment with alkalinised lignocaine appears to be effective in reducing the pain during propofol injection.