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A1065
October 21, 2017
43029.416667 - 43029.5
Room Exhibit Hall B2 - Area E
The Use of Ketamine Infusions for Refractory Headaches: A Retrospective Analysis
Ashwin Rangavajjula, M.D., Mauricio Hernandez, B.S., Amir C. Dayan, M.D., Eric S. Schwenk, M.D., Eugene R. Viscusi, M.D.
Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States
Disclosures: A. Rangavajjula: None. M. Hernandez: None. A.C. Dayan: None. E.S. Schwenk: None. E.R. Viscusi: Funded Research; Self; AcelRx, Cumberland, Pacira. Consulting Fees; Self; Mallinckrodt, Merck, Salix, Astra Zeneca, Trevena
 

Introduction

Ketamine, a NMDA antagonist and potent analgesic, effectively treats many painful conditions and has shown promise in patients with chronic migraine and other intractable headaches (1). The purpose of this retrospective study was to evaluate the analgesic effects of ketamine infusions on patients with treatment refractory headaches at an established center. We hypothesized that patients would have a reduction in headache pain by two or more points (0 to 10 scale) by the end of their admission at infusion rates lower than the pre-determined maximum rate.

Methods

Following IRB approval, we conducted a retrospective review of patients admitted to Thomas Jefferson Hospital who received ketamine infusions managed by our acute pain service for migraine or other intractable headaches from 1/2014 to 12/2016. The data sources were the daily acute pain notes and electronic medical charts. Data extracted included: demographics and medications; initial and daily pain rating (numerical rating scale 0-10 with 0=no pain and 10=worst pain imaginable); daily ketamine infusion rate; and presence of adverse effects. One- and two-way ANOVA was utilized for measured endpoints. Statistical significance was set at p < 0.05. The ketamine infusion protocol at our institution sets a soft upper limit of 1 mg/kg/hr, which can be increased at attending discretion. Pain ratings are reported as mean values with standard error of the mean (SEM).

Results

A total of 61 subjects were included in this retrospective study. The mean headache pain rating at admission was 7.5 ± 0.2 (SEM) vs. 3.4 ± 0.3 (SEM) on discharge. There was a statistically significant difference between the initial, lowest and end pain ratings (p < 0.001; Figure 1). The mean length of infusion was 5.1 days and the day of lowest pain rating was day 4 (Table 1). Patients achieved their lowest pain rating at mean ketamine rates 30.8 ± 3.6 mg/hr less than their maximum dose (1 mg/kg) per our protocol. Adverse effects were general mild and did not result in infusion discontinuation, except for one patient (Table 2). This patient requested discontinuation after 1 day of treatment.

Discussion

This retrospective study demonstrates that sub-anesthetic ketamine infusions improved short-term analgesia for refractory headaches. Adverse effects were generally mild. Prospective studies are needed to determine optimal dose and duration and assess long-term outcomes.

Reference

1. Lauritsen C, et al. J Headache Pain 2016;17:106
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