In this episode, I’ll discuss two doses of ketamine for analgesia in the ED.
Low dose ketamine for analgesia is generally considered to be doses of 0.5 mg/kg IV or less. This dose is below the threshold that will cause dissociative anesthesia, and ketamine is considered to have a dose-dependent analgesic response at this level.
According to a systematic review and meta-analysis, the majority of studies using ketamine as analgesia in the ED focus on the 0.3 mg/kg IV dose. However, doses as low as 0.15 mg/kg IV have been used.
Researchers published recently in Academic Emergency Medicine a randomized, prospective, double‐blinded, non‐inferiority trial looking to compare the use of 0.3 vs 0.15 mg/kg IV ketamine for analgesia in the ED.
They studied 49 patients age 18‐59 years presenting to the ED with acute moderate to severe pain. Patients were randomized to IV ketamine 0.15 mg/kg or 0.3 mg/kg given over 15 minutes.
The primary endpoint was the pain score between groups at 30 minutes.
The mean score at 30 minutes was 4.7 in the 0.15 mg/kg group and 5 in the 0.3 mg/kg group, and this met the trial’s criteria for non-inferiority.
The most frequent types of pain treated were abdominal and musculoskeletal pain, but there were also some patients with flank pain, back pain, and headache.
The authors concluded:
Based on these findings, a dose of 0.15mg/kg IV ketamine over 15 minutes should be considered over higher doses for
analgesia in the ED.
The main issue with low dose ketamine in the ED is logistics, because most studies use a 15-minute infusion to lower the side effect rate compared to injection, and this takes longer to prepare and deliver to the bedside compared to boluses of opioids given IV push.
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