Intravenous Ketamine Infusion as an Adjuvant to Morphine in a 2-Year-Old With Severe Cancer Pain From Metastatic Neuroblastoma

Abstract

A 2.8-year-old female patient (11.6 kg) was admitted to the hospital for uncontrolled pain and swelling in the left leg relating to a metastatic neuroblastoma. Initially, her pain was managed with oral morphine 2 mg (approx. 0.2 mg/kg) every 4 hours. Because she was quite somnolent but still in significant pain, analgesia was then changed to methadone 1 mg orally every 6 hours (approximately 0.1 mg/kg/dose) and was eventually increased over 36 hours to 2 mg every 6 hours (approximately 0.2 mg/kg/dose). She received oral methadone 0.6 mg (approximately 0.05 mg/kg) every 4 hours as needed for breakthrough pain. She continued to have severe pain and experienced side effects, including respiratory depression, sedation, visual hallucinations, and vomiting. An intravenous ketamine infusion was started at 100 microg/kg/hour. Regular opioid administration was ceased, but she was given intravenous morphine 0.5 to 0.75 mg for breakthrough pain. She required only zero to three doses of breakthrough morphine per day, initially. After starting the ketamine infusion, her pain control improved and her symptoms of opioid toxicity abated. She was more alert and able to partake in limited activities. As a result of pain from progressive disease, the ketamine infusion was increased to 200 microg/kg/hour after 6 days with positive results. Her condition continued to deteriorate. An intravenous morphine infusion was initiated 2 weeks after starting the ketamine infusion and was eventually increased to 50 microg/kg/hour. One week later, she died with reasonable pain control. This case illustrates the use of ketamine as an effective analgesic in an adjuvant setting in a pediatric patient with advanced poorly controlled cancer pain. Ketamine not only eased the child's suffering while preserving life but also improved her quality of life by maintaining the child's ability to communicate and engage in activities.