 The proposed study will be conducted using existing dedicated clinical and research space in St. Louis Childrens Hospitals Emergency Department, Pediatric Clinical Research Center PCRC, and Orthopedic Clinic. This project has 3 major aims and 1 exploratory aim addressed by a prospective randomized blinded placebo controlled drug trial to test whether a pharmacological strategy can prevent NMDA receptor hypofunction-induced behavioral and cognitive dysfunction in pre- and post-pubertal children. Based on previous preclinical and clinical research on the effects and blockade of the effects of ketamine and similar compounds, the study investigators have carefully selected a dose of the alpha-2 adrenergic agonist dexmedetomidine that will permit this study to be conducted with low risk to enrolled subjects who are undergoing clinically-indicated ketamine sedation for forearm fracture reduction. 