Subdissociative Dose Ketamine for Treatment of Acute Pain in Subjects With Chronic Pain

This is a prospective, randomized controlled trial which will be conducted to determine whether sub-dissociative dose ketamine (SDDK) can improve pain control in subjects with chronic pain syndrome presenting to the emergency department with exacerbation of their chronic pain. The investigators also aim to determine whether use of SDDK can reduce the amount of subsequent opioid pain medications required for adequate pain relief in this population.