The Use of Ketamine as an Adjunct to Treating Opioid Refractory Cancer-Related Pain in the Emergency Department

Effectiveness of Low-Dose Ketamine Infusion in Opioid Refractory Cancer Pain: A Case Report

Most patients with advanced cancer experience debilitating pain, which significantly affects their quality of life and has both physical and psychological implications. Opioids have been the mainstay of treatment for chronic cancer pain, but some people develop serious adverse effects or may become refractory to opioid use. There is always a need and search for alternative non-opioid analgesics with an acceptable safety profile, and one such drug is ketamine. In this era of evolving analgesic therapeutics, ketamine has been noted to have favourable results. Ketamine, a phencyclidine analogue, is an N-methyl-D-aspartate antagonist (NMDA), and it has been shown to have an analgesic effect at sub-anaesthetic doses by blocking NMDA-induced pain sensitization and enhancing opioid receptor sensitization. This is a case report of a 46-year-old Indian female with recurrent metastatic adenocarcinoma endometrium (International Federation of Obstetrics and Gynecology (FIGO) Grade II) involving the vaginal vault, rectum, and adrenal glands, along with para-rectal, bilateral iliac, and retroperitoneal nodal metastases, in which ketamine infusion was used successfully to alleviate the pain that was initially not controlled with an incremental dose of opioids. The patient presented with progressive pain in the peri-anal region, rated 8/10 on the Numerical Pain Rating Scale (NRS), following which she was treated with escalating doses of intravenous (IV) fentanyl, but with little to no relief. In view of the patient's opioid-resistant pain, she was started on a low-dose ketamine IV infusion (50 mg in 50 ml of 0.9% NS) as "burst therapy," at infusion rates of 0.02 mg/kg/hr-0.08 mg/kg/hr, with adequate pain relief occurring at 0.08 mg/kg/hr. Literature suggests weight-based dosing of ketamine ranging from 0.06 mg/kg/hr to 0.8 mg/kg/hr was previously used to achieve satisfactory results. In this patient, even lower doses were effectively used to achieve optimum long-term analgesia, cause an upliftment in the patient's overall mood and quality of life, and cause a significant reduction in opioid usage. However, further research is required to assess the efficacy of ketamine at such doses and its effect on opioid consumption. This case report will promote further study regarding optimum IV ketamine dosing and administration in the management of opioid-refractory pain in cancer patients, especially in the Indian population.

The immunomodulatory effect of ketamine in colorectal cancer surgery: a randomized-controlled trial

PURPOSE

Ketamine's inhibitory action on the N-methyl-D-aspartate receptor and anti-inflammatory effects may provide beneficial immunomodulation in cancer surgery. We investigated the effect of subanesthetic-dose ketamine as an adjunct to desflurane anesthesia on natural killer (NK) cell activity and inflammation in patients undergoing colorectal cancer surgery.

METHODS

A total of 100 patients were randomly assigned to a control or ketamine group. The ketamine group received a bolus of 0.25 mg·kg^-1 ketamine five minutes before the start of surgery, followed by an infusion 0.05 mg·kg^-1·hr^-1 until the end of surgery; the control group received a similar amount of normal saline. We measured NK cell activity and proinflammatory cytokines (interleukin-6 [IL-6] and tumour necrosis factor-α [TNF-α]) before surgery and one, 24, and 48 hr after surgery. C-reactive protein (CRP) was measured before surgery and one, three, and five days after surgery. Carcinoembryonic antigen and cancer recurrence/metastasis were assessed two years after surgery.

RESULTS

The NK cell activity was significantly decreased after surgery in both groups, but the change was not different between groups in the linear mixed model analysis (P = 0.47). Changes in IL-6, TNF-α, CRP, and carcinoembryonic antigen levels were not different between groups (P = 0.27, 0.69, 0.99, and 0.97, respectively). Cancer recurrence within 2 years after surgery was similar between groups (10% vs 8%, P = 0.62).

CONCLUSIONS

Intraoperative low-dose ketamine administration did not convey any favourable impacts on overall postoperative NK cell activity, inflammatory responses, and prognosis in colorectal cancer surgery patients.

TRIAL REGISTRATION

www.clinicaltrial.gov (NCT03273231); registered 6 September 2017.