Opioids and traditional adjuvant medications are frequently prescribed for the management of moderate to severe cancer pain with good effect. However, there are many cases, in which patients experience severe opioid refractory cancer pain. Ketamine is being used more frequently in the hospice and palliative setting to manage opioid refractory pain, although high-quality evidence regarding its effectiveness is lacking. It seems certain patients respond favorably to ketamine, while others experience no effect. Studies have not yet identified factors associated with a favorable response to ketamine. We present a case describing the successful treatment of high-dose opioid refractory cancer pain with a subanesthetic ketamine infusion and propose the novel use of a preinfusion test bolus of ketamine to identify patients who are likely to respond favorably to an infusion.
Keywords: ketamine; opioid refractory cancer pain; test bolus.