Is ketamine safe and effective in excited delirium?
March 29, 2016, 12:43 pm
Ketamine as Rescue Treatment for Difficult-to-Sedate Severe Acute Behavioral Disturbance in the Emergency Department. Isbister GK et al. Ann Emerg Med 2016 Feb 10 [Epub ahead of print]
Rapidly sedating a toxicology patient who presents with excited delirium is a critical — yet often difficult — action. These patients are typically difficult to control and resistant to sedation with commonly used agents such as benzodiazepines and antipsychotics. They also have high mortality rates. The key to obtaining good outcomes in these cases is prompt evaluation and support, focusing on the ABCs and hydration, as well as early detection and treatment of hypoglycemia and hyperthermia.
The aim of this prospective observational study was to evaluate the safety and efficacy of ketamine as rescue therapy for sedating excited delirium patients who had not responded to standard agents. As part of a therapeutic protocol, adult (> 16 years old) patients with excited delirium were given up to 2 doses of 10-mg IM droperidol 15 minutes apart. If sedation was not achieved, IM ketamine (4 – 6 mg/kg) was recommended after consult with the toxicology service.
Of nearly 1300 excited delirium patients who received droperidol, 49 were not adequately sedated after 2 doses. Five of the 49 were not sufficiently sedated within 120 minutes of receiving ketamine and/or required additional sedation. Many of those 5 patients seem to have received IM ketamine doses below the recommended 4 – 6 mg/kg.
There were 3 minor adverse effects: 2 patients vomited, and 1 developed oxygen desaturation down to 90% that responded readily to supplemental oxygen.
Some clinicians are wary of using ketamine in excited delirium patients for fear that the drug’s weak inhibition of catecholamine reuptake might exacerbate hypertension and tachycardia, and cause emergent hallucinations. The authors of an accompanying editorial note that one peer reviewer who evaluated the paper wrote:
This is just crazy . . . [T]he last thing we need is for a bunch of residents or docs to whack psych patients with ketamine in order to ‘sedate’ them.
Yet ketamine is gaining increased acceptance as a sedating agent in excited delirium. Recently in Emergency Medicine News, Dr. James Roberts discussed this topic and concluded:
Ketamine appears to be an ideal drug for the patient with unknown pathology who presents in an uncontrolable and violent state.
He pointed out that advantages of ketamine in this setting included rapid onset after IM administration, relatively short duration (30-40 minutes), and preservation of reflexes.
From a toxicological perspective, there are several important points to make about this paper:
- The data is not clean, since there were a number of protocol violations involving included patients
- Only 7 of the 49 eligible patients had psychostimulant-induced excited delirium
- The fact that 43 patients had pre-administration blood pressures recorded suggests that many did not exhibit full-blown excited delirium
- The study looked at ketamine only as a rescue — not primary — sedative