Preemptive dexmedetomidine to prevent propofol injection pain in children

The incidence of propofol injection pain is high in children, but no methods have been found to suppress it completely. This study intends to evaluate the efficacy of dexmedetomidine-midazolam in preventing propofol injection pain in children. One-hundred ASA I patients, aged 3-12 years, weighing 15-53 kg, undergoing elective surgery were randomized into two groups of 50 each, using computer-generated random numbers. Normal saline 0.15 ml/kg in Group C or dexmedetomidine 0.6 mu g/kg in Group D was infused IV over 10 min. Then midazolam 0.06 mg/kg was administered immediately; 2 min after aforementioned treatments in each group, all patients received propofol 2 mg/kg (propofol was mixed with lidocaine 1 mg/ml in Group C) at an average rate of 0.2 ml per 1 s. Another anesthesiologist, blind to the pretreatment, recorded the occurrence of injection pain using a four-graded pain scale: 1 = no pain (no reaction to injection), 2 = slight pain (minor verbal/facial response or motor reaction to injection), 3 = moderate pain (clear verbal/facial response or motor reaction to injection) and 4 = severe pain (the patient both complained of pain and withdrew the arm). Forty (80 %) patients in Group C (control) had injection pain; however, none of patients in Group D had any injection pain. The total incidence of profol-induced pain in Group C was significantly higher (P < 0.01). There were no instances of bradycardia or low blood pressure with either treatment in this study. Pretreatment with dexmedetomidine 0.6 mu g/kg, then midazolam 0.06 mg/kg could suppress propofol injection pain in children.