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Ketamine Safe, Effective for Difficult-to-Sedate ED Patients

NEWSCASTLE, AUSTRALIA – Sedating patients with severe acute behavioral disturbance sometimes can be extremely challenging in the emergency department setting.

That’s why a new Australian study is so significant. The report, published recently in Annals of Emergency Medicine, finds that using ketamine appears to be safe and effective in those situations.

"Difficult to sedate patients with behavioral disturbances are highly problematic for emergency department staff," said Geoff Isbister, MD, of the Clinical Toxicology Research Group at the University of Newcastle in Newcastle, Australia. "Although such patients are uncommon, they cause significant disruption and danger to emergency department staff and consume time and resources required for other patients. Ketamine is a reasonable third-line agent to use on these patients once other sedation options have been exhausted."

During the study, only 10% of 49 ED patients with acute behavioral disturbances who were treated with ketamine failed to achieve sedation within two hours or required additional sedation within one hour. In most cases, patients were treated with ketamine only after sedation was attempted with droperidol. Average time to sedation after ketamine administration was 20 minutes.

The patients – median age 37, 57% male, and more than a third involved with police – received rescue ketamine at two hospitals over 27 months.

Among those patients, previous sedation included droperidol, 10 mg; droperidol,10+10 mg; droperidol, 10+10+5 mg; droperidol, 10+10+10 mg; combinations of droperidol and benzodiazepines; or midazolam alone, according to the study.

In terms of ketamine, the median dosage was 300 mg, with a range of 50 to 500 mg. Of the five patients who were not sedated within 120 minutes or required additional sedation within an hour, four of them had received 200 mg or less.

Side effects were minimal, according to the report, with two patients vomiting after ketamine administration and one having transient oxygen desaturation to 90% that responded to oxygen.

“Ketamine appeared effective and did not cause obvious harm in this small sample and is a potential option for patients who have failed previous attempts at sedation,” study authors conclude. “A dose of 4 to 5 mg/kg is suggested, and doses less than 200 mg are associated with treatment failure.”

"Most agitated and aggressive patients in the emergency department will either respond to verbal de-escalation or oral sedation, or be rapidly sedated with droperidol," Isbister added in an Annals of Emergency Medicine press release. "For the small number who don't, we have ketamine."