PALM SPRINGS, CA — Patients who underwent multiple consecutive days of outpatient ketamine infusion for chronic neuropathic pain had minimal side effects and stable hemodynamics, a retrospective chart review presented during the 2012 American Academy of Pain Medicine Annual Meeting found.

These results suggest ketamine “may therefore offer a safe alternative for recalcitrant neuropathic pain in an outpatient setting,” noted Elvis W. Rema, MD, of New York Presbyterian, NY, and colleagues.

The investigators initiated a chart review to study the safety and efficacy of outpatient multiday low-dose ketamine infusions which, although useful in reducing neuropathic pain not responsive to other treatment modalities, have the potential to cause side effects such as hallucinations, cognitive disturbances, nausea, vomiting, and hemodynamic instability.

All patients undergoing outpatient ketamine infusion for neuropathic pain from July 2009 to August 2010 were included. A total of 34 patients were identified, 12 males and 22 females. The dose of ketamine was incrementally increased daily from 0.2mg/kg/hr to 0.4mg/kg/hr and 0.6mg/kg/hr for four hours. The numerical rating score (NRS) for pain was measured before and after ketamine infusion. Blood pressure, heart rate, and incidence of nausea were measuring before, during, and after infusions.

No significant differences were observed among the three doses of ketamine with respect to systolic and diastolic blood pressures, heart rate, or nausea incidence. A significant decrease in NRS was found between the 0.2mg/kg/hr and 0.6mg/kg/hr doses of ketamine (P=0.019) and the 0.4mg/kg/hr and 0.6mg/kg/hr doses (P=0.005); however, there was no significant difference in NRS change between the 0.2mg/kg/hr and 0.4mg/kg/hr groups.

Investigators concluded that ketamine may be a safe alternative for recalcitrant neuropathic pain in an outpatient setting. However, “further prospective double-blind randomized studies that account for confounding factors need to be performed to define the role of outpatient ketamine as an analgesic adjuvant for the management of neuropathic pain syndromes,” they stated.