In this episode I’ll:

1. Discuss evidence on the efficacy of ketamine IM for acute behavioral emergencies.

2. Answer the drug information question “Can a patient with an allergy to contrast media receive amiodarone?”

3. Share a resource for antimicrobial stewards.

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Article

Ketamine as Rescue Treatment for Difficult-to-Sedate Severe Acute Behavioral Disturbance in the Emergency Department

Lead Author: Geoffrey Kennedy Isbister

Published in Annals of Emergency Medicine May 2016

Background

I’ve discussed the idea of using ketamine as rescue therapy for acute behavioral emergencies in episode 16 & episode 84.

The longer the emergency lasts, the greater the risk of physical harm or bodily fluid exposure to hospital staff. It can take 10 minutes or multiple doses for IM benzodiazepines / antipsychotics to work.

Objective

The authors sought to investigate the effectiveness and safety of ketamine to sedate patients with severe acute behavioral disturbance who have failed previous attempts at sedation with droperidol and/or benzodiazepines.

Methods

The study was a subgroup of difficult to sedate patients with severe acute behavioral disturbance from the prospective (DORM II) study. All patients were given ketamine IM 4 to 6 mg/kg for sedation after failed sedation attempts. The primary outcome was the number of patients who failed to sedate within 120 minutes of ketamine administration or required further sedation within 1 hour.

Results

Forty-nine patients at 2 emergency departments received rescue ketamine. The median age was 37 years, and 28 of the patients were male. Previous sedation included droperidol (10 to 30 mg total dose) and / or benzodiazepines. The median dose of ketamine was 300 mg (range 50 to 500 mg).

Five patients were not sedated within 120 minutes or required additional sedation within 1 hour. Four of these 5 patients received 200 mg or less of ketamine. Median time to sedation post ketamine was 20 minutes. Three patients had adverse effects; 2 had vomiting, and a third had a transient oxygen desaturation to 90% that responded to oxygen.

Conclusion

The authors concluded:

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. A dose of 4 to 5 mg/kg IM is suggested, and doses less than 200 mg are associated with treatment failure.

Discussion

While the study took place in an emergency department setting, I believe the results can be generalized to other critical care settings such as medical / surgical intensive care units.

The study demonstrates efficacy of ketamine for rescue sedation in acute behavioral emergency. However with only 49 patients, the safety of such an approach can not be certain.

As an accompanying editorial points out – ketamine can cause a catecholamine surge, which may be enough in an acutely agitated patient to precipitate a cardiac event. Just like TASERs, which are safe in healthy patients but occasionally fatal in violent individuals, ketamine might have rare but serious side effects when used for this indication.

I conclude that antipsychotics and/or benzodiazepines are still first line for acute behavioral emergencies, but that ketamine may be used if other agents fail to work.

Drug information question

Q: Can a patient with an allergy to contrast media receive amiodarone?

A: Yes.

A 2012 study concluded:

The incidence of hypersensitivity reaction to amiodarone in hospitalized patients with a listed allergy to iodine or iodinated contrast agents was less than 1%, and all identified reactions were without long-term sequelae. Allergy to iodine and iodinated contrast agents may not be a valid absolute contraindication to amiodarone administration in the inpatient setting.

Resource

Listener “Pharmacy Greg” provided the resource for this episode. It is something that clinicians with an interest in antibiotic stewardship might find very useful. Greg writes:

I particularly like that you highlight useful references in many of the episodes. I am not sure if you were aware of this already, or think this is relevant to your listeners, but I wanted to let you know that this year is the first year that CLSI [Clinical and Laboratory Standards Institute] has made it’s breakpoint guide (the M-100 document) FREE online. See here http://clsi.org/m100/. I think that’s pretty exciting and wasn’t sure if you wanted to share that with listeners.

Knowledge of these sensitivity breakpoints can help clinicians prescribe antibiotics effectively.

If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.

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