- Does the addition of fentanyl to bupivacaine in caudal epidural block have an effect on the plasma level of catecholamines in children? Gaitini, L.A., Somri, M., Vaida, S.J., Yanovski, B., Mogilner, G., Sabo, E., Lischinsky, S., Greenberg, A., Levy, N., Zinder, O. Anesth. Analg. (2000)