Dexmedetomidine-ketamine combination and caudal block for superficial lower abdominal and genital surgery in children

Background The use of dexmedetomidine-ketamine combination to perform different diagnostic and surgical pediatric procedures has increased. The optimal ketamine dose to combine with dexmedetomidine has not been determined. The goal of this study was to determine the ED50 and ED95 of ketamine, which in combination with, dexmedetomidine (1 mu g.kg(-1)) provides an adequate anesthetic effect to perform a caudal block and then the ensuing superficial lower abdominal or genital surgery. Material and Methods Twenty-five patients, aged 1-8 years, scheduled for superficial lower abdominal or genital surgery, were studied. All patients received an intravenous dose of dexmedetomidine 1 mu g.kg(-1) and a random dose of ketamine from 1 mg.kg(-1) to 2 mg.kg(-1). After ketamine administration, a caudal block was performed and then surgery was initiated. Hemodynamics, respiratory variables, sedation level, and postoperative complications were recorded. The ED50 and ED95 of ketamine were calculated using logistic regression analysis. Results The ED50 and ED95 of ketamine to perform a caudal block were 1.53 (1.29-1.76) mg.kg(-1) and 2.25 (1.63-2.88) mg.kg(-1), respectively. The ED50 and ED95 of ketamine to perform a caudal block and to complete the entire procedure were 1.76 (1.57-1.95) mg.kg(-1), and 2.21 (1.77-2.64) mg.kg(-1), respectively. Three patients presented mild, self-limited, intraoperative bradycardia. Conclusions These results suggest that adding ketamine 2 mg.kg(-1) to dexmedetomidine 1 mu g.kg(-1) should produce an effective anesthetic level to perform a caudal block and the ensuing superficial lower abdominal or genital surgery in children.