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October 13, 2012
1:00:00 PM - 2:30:00 PM
Room 101
Safety of Low-Dose Ketamine Infusions on Non-Monitored Inpatient Wards: A Five Year Experience
Carlton Brown, M.D., Benjamin Daxon, M.D.
WRNMMC - Bethesda, Bethesda, Maryland, United States



Low-dose ketamine infusions are increasingly used as non-opioid adjuncts for acute pain control. At WRNMMC-B ketamine has become an integral pain management tool for our Wounded Warriors. With complex combat wounds these soldiers often exhibit remarkable opioid tolerance, evolving neuropathic pain, phantom limb pain, allodynia, and opioid-induced hyperalgesia. Prior to 2007, all ketamine infusions were restricted to an ICU or PACU. We instituted a low-dose ketamine infusion protocol for ward use in 2007. A rapidly growing literature (1) demonstrates ketamine’s analgesic efficacy, yet we could find no specific publications addressing its infusion safety on non-monitored wards. We reviewed our five year experience.


Pharmacy utilization audits and associated patient records were reviewed for all intravenous ketamine infusions from 2007 through 2011. Patient locations were stratified as either “monitored” or “unmonitored.” (Patients receiving ketamine in the ICU were there due to surgical injuries.) Duration of administration (days), number of syringes issued per patient, and total ketamine dose issued (mg) were analyzed. Actual hourly infusion rates are titrated frequently during clinical administration based on therapeutic responses. Average rates (mg/hr) for 24 hour periods were calculated and reported for all patients issued three or more syringes. Patients issued only one or two syringes were excluded from dosage calculations due to high fractional medication wastage upon termination of the infusion. The number of ketamine infusions instituted per year and average infusion doses were computed to track changing practice patterns.


249 patients received 273 ketamine infusions over 1837 patient-days during five years. Mean ketamine dosage was 28.0 mg/hr with a range of 10.9 to 69.4 mg/hr. Mean infusion duration was 7.6 days with a range of 1 to 65 days. Our results are summarized in Table 1. The number of ketamine infusions has increased sharply at our institution. (Table 2) The average calculated dose has not substantially changed over this epoch. (Table 3)

No patient required an elevated acuity of care due to a complication or side-effect from ketamine. Only two adverse events (safety reports) occurred over five years. One event involved unintentional flushing of an IV line with a ketamine infusion attached. One patient had a ten-fold concentration mismatch between the infusion pump and syringe concentration settings. The patient self-reported psychomimetic changes after six hours; the infusion was stopped, the mismatched syringe and pump settings corrected, and the infusion resumed after three hours. No elevation of care was required in either case.


Our five year experience with low-dose ketamine infusions on wards suggests a high level of patient safety.

Substantial effort was expended to safely transition this technology to our wards. Institutional policy approvals, training for ward staff, establishing nursing competencies for ketamine administration, patient and family education, and in-house availability of an APS team were all part of this evolution. Based on our data, we anticipate increased future ketamine infusion use in ward settings.

1. Bell RF, et al. Perioperative ketamine for acute postoperative pain. Cochrane Database Syst Rev. 2006 25:CD004603.
Figure 1

Copyright © 2012 American Society of Anesthesiologists