Author: Amanda Hu, MD
Affiliated institution: UC Irvine Medical Center
Abstract:
Background: Intractable chronic pain can occur in patients with metastatic cancer who have received opioids for extended periods of time. A ketamine-induced coma has been induced in some individuals as a way to assist in the “resetting” of pain receptors, during which a patient’s usual opioid regimen is largely decreased or eliminated altogether.
Case description: A 39-year-old female with history of metastatic breast cancer and worsening chronic pain treated with intrathecal fentanyl pump and fentanyl PCA was admitted to UC Irvine Medical Center for a five-day ketamine coma. Her previous daily pain regimen included: ketamine 360mcg, 8 mg clonazepam, 200mcg fentanyl transdermal patch, 600 mcg fentanyl oral spray, baclofen 80mg, and gabapentin 600mg qAM, gabapentin 1200mg; she was then started on a fentanyl intrathecal pump which was eventually increased to 400 mcg/day, as well as a fentanyl PCA pump w/ 200mcg basal and 200 mcg PRN every 6 minutes for pain. However, the patient had become hyperalgesic, with acute distress from “whole body” pain, possibly exhibiting some allodynic components. For example, the application or removal of a tegaderm bandage would elicit severe 10/10 pain.
Patient was admitted, subsequently intubated and treated with ketamine and propofol gtt (at 3mg/kg/hr and 30mcg/kg/in, respectively), and all systemic opioids were discontinued including the fentanyl PCA with basal rate. Her intrathecal pain pump was decreased just prior to admission by her pain physician from 400mcg/day to 200mcg/day, then decreased further after admission to 50mcg/day. After five uneventful days, the patient self-extubated, just hours before her scheduled wakeup. Patient awoke in no acute distress or discomfort, consistently describing her pain as 0-1/10. Patient’s intrathecal pump was decreased by about 10% per day, from 50mcg/day to 44mcg/day, then to 40mcg/day at which point patient began having moderate (6/10 or higher) back and abdominal pain. After increasing the intrathecal fentanyl pump back to 44mcg/day, patient’s pain was again well controlled and she was discharged shortly afterwards.
Discussion: While the patient’s pain was clearly improved upon waking from the ketamine coma, she did have significant anxiety and was started on buspirone 15mg BID, diazepam 5mg PRN, and restarted on home venlafaxine 225mg QD. The patient also had some brief visual hallucinations two days after waking, likely residual effects of ketamine combined with lack of adequate sleep hygiene. Additionally, the patient took about two days to become completely oriented and alert; initially she was fairly sedated, although appropriate and able to follow commands. Overall, she had a dramatic decrease in her pain requirements as well as in her perceived pain, observed consistently by multiple providers as well as verified by her husband, and no lasting adverse effects from the ketamine/propofol. She was discharged home with significant improvements in her quality of life. Her experience has powerful implications for other patients in similar positions of severe chronic pain refractory to high dose opioids.
