Assessment of low-dose i.v. ketamine infusions for adjunctive analgesia.

PURPOSE: The results of a study evaluating all patients treated with adjunctive low-dose ketamine for analgesia over a three-year period are presented. METHODS: A retrospective single-center analysis evaluated all adult patients who received adjunctive low-dose i.v. ketamine infusions from September 2010 to September 2013. Patients were excluded if they received concomitant oral ketamine, if ketamine was used to treat seizures, or if the patients received ketamine boluses without infusion. The primary endpoint was to identify the patient populations receiving low-dose intravenous ketamine. Secondary endpoints included an assessment of clinical variables and adverse events. Demographic information, level of care, clinical variables, adverse events, and patient outcomes were recorded. RESULTS: A total of 460 patients were evaluated. Of these, 396 were included in this analysis. Ketamine was administered to 69.9% of the patients in association with a surgical procedure, as opposed to 30.1% who received ketamine for medical management of pain. The percentage of patients receiving intensive care unit level care was 24%. Before initiation of ketamine, patient-reported pain scores averaged 7.1 ± 2.63 S.D.; during the ketamine infusion, patient-reported pain scores averaged 6.42 ± 2.01 S.D.; (p < 0.001). In the safety analysis, hypertension occurred in 21.4% of patients, hypotension occurred in 15.1% of patients, and respiratory depression occurred in 6.3% of patients. CONCLUSION: A retrospective review found that patients receiving continuous ketamine infusions in addition to opioid therapy saw a reduction in pain scores and experienced cardiovascular adverse effects in greater than 20% of cases.