Intranasal Ketamine for Analgesia in the Emergency Department: A Prospective Observational Series

Abstract

The objective was to examine the feasibility, effectiveness, and adverse effect profile of intranasal ketamine for analgesia in emergency department (ED) patients. This was a prospective observational study examining a convenience sample of patients aged older than 6years experiencing moderate or severe pain, defined as a visual analog scale (VAS) score of 50mm or greater. Patients received 0.5 to 0.75mg/kg intranasal ketamine. Pain scores were recorded on a standard 100-mm VAS by trained investigators at baseline, then every 5minutes for 30minutes, and then every 10minutes for an additional 30minutes. The primary outcome was the number and proportion of patients experiencing clinically significant reductions in VAS pain scores, defined as VAS reductions of 13mm or more, within 30minutes. Secondary outcomes included the median reduction in VAS, the median time required to achieve a 13mm reduction in VAS, vital sign changes, and adverse events. Continuous data are reported with medians and interquartile ranges (IQRs). The Wilcoxon signed-ranks test was used to assess changes in VAS scores. Adverse effects are reported with proportions and 95% confidence intervals (CIs). Forty patients were enrolled with a median age of 47years (IQR= 36 to 57years; range= 11 to 79years) for primarily orthopedic injuries. A reduction in VAS of 13mm or more within 30minutes was achieved in 35 patients (88%). The median change in VAS at 30minutes was 34mm (44%). Median time required to achieve a 13mm VAS reduction was 9.5minutes (IQR= 5 to 13minutes; range= 5 to 25minutes). No serious adverse effects occurred. Minor adverse effects included dizziness (21 patients, 53%; 95% CI=38% to 67%), feeling of unreality (14 patients, 35%; 95% CI=22% to 50%), nausea (four patients, 10%; 95% CI=4% to 23%), mood change (three patients, 8%; 95% CI=3% to 20%), and changes in hearing (one patient, 3%; 95% CI=0% to 13%). All adverse effects were transient and none required intervention. There were no changes in vital signs requiring clinical intervention. Intranasal ketamine reduced VAS pain scores to a clinically significant degree in 88% of ED patients in this series. Adverse effects were minor and transient. Intranasal ketamine may have a role in the provision of effective, expeditious analgesia to ED patients.