Continuous ketamine infusion for the management of opioid-induced hyperalgesia following amputation.

We discuss the use of an inpatient multi-day continuous intravenous ketamine infusion for the treatment of opioid-induced hyperalgesia (OIH) and high fentanyl requirements in the case of a patient with a background of fibromyalgia/central sensitisation syndrome who underwent a complicated post-operative course following a right below-knee amputation for high-grade myxoid fibrosarcoma. The patient was successfully tapered off a total fentanyl patch dose of 162 mcg/hour every 72 hours (morphine equivalent dose of 389 mg/day) to short-acting hydromorphone 2 mg orally two times per day as needed (equivalent of 8 mg morphine sustained-release twice per day) during a 2-week admission with only mild withdrawal symptoms. We discuss the pharmacology of ketamine and its possible application in the treatment of OIH.