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Ketamine: Friend or Foe?

Updated: Jan 26

We hope to publish a mix of operations/leadership and clinical posts as we expand our blog. This clinical post is a little more complex and very near and dear to my heart, so I appreciate you bearing with me. Hopefully you learn something new!

My history with ketamine

When we started routinely using ketamine at my workplace in 2015 or 2016, I found that many clinicians (physicians, paramedics, and nurses alike) had been turned off by ketamine and thought of it as their foe -- the absolute worst choice for procedural sedation or chemical restraint. Whenever I dived into the experiences and rationale behind these thoughts, it became apparent that the fear of using ketamine was typically due to a fundamental lack of understanding of the drug and its properties -- particularly the dose continuum and administration-related side effects. I've been preaching the good word of ketamine since 2016; spreading this knowledge to other agencies and at regional and national EMS and nursing conferences.

Ketamine today

Our understanding of ketamine is even better today. We know it's safe and have busted many of the myths associated with it -- making ketamine even more of a no-brainer. It's a true "multi-tool" of drugs with many indications and uses. Of course, like any medication, it does have risks. We also face some recent challenges, including negative press and legislation surrounding deaths that included administration of ketamine. We'll address those in a separate post.

Why ketamine

Basically, because it's safe and offers a wide variety of uses and benefits. Ketamine has an excellent safety record when used appropriately. One of the amazing things about ketamine is that it can provide rapid and full dissociation with preserved respiratory effect. At a dissociative dose, this is a perfect drug for procedural sedation, delayed-sequence intubation, and chemical restraint. Of course, we can also use it for analgesia. There is also some promising research that ketamine may be able to be used as an antiepileptic and for treatment-resistant depression.

The dose continuum

One of the most important factors in the safe use of ketamine is understanding the dose continuum. This is not an original idea of mine. I first heard of it from Reuben Strayer, MD describing the ketamine brain continuum. The basic idea is that the effect of ketamine is largely dose dependent, and the dose-effect relationship can vary widely in different patients. If you dose under about 0.2 mg/kg IV, you'll likely only see analgesic effects. If you dose over 1.5 mg/kg IV or so, you'll almost always dissociate the patient. The problem comes between these doses... you don't really know what will happen! This could include uncomfortable "recreational" effects (like changes in perception, hallucinations) or, worse, partial dissociation.

For example, if the patient in your helicopter becomes combative, giving them 0.5 mg/kg IV (or even 1 mg/kg!) could partially dissociate them, making them scared, aggressive, and possibly more dangerous to themselves and staff. If you didn't understand the continuum, you might associate ketamine as the cause of this worsening situation, switch to a different antipsychotic or sedative, and never want to use ketamine again. If you do understand the continuum, you would just give a larger dose and fully dissociate the patient, safely and quickly resolving the situation.

Reversing the continuum

When you give ketamine, you can give a large dose to skip phases (i.e. recreational and partial dissociation). This is why you should always bolus ketamine to achieve dissociation before starting a continuous infusion. However, you can't skip phases as the body metabolizes and eliminates ketamine. All people will go through some form of partial dissociation and recreational effects on their way out. This is why pre-treatment comfort including verbal reassurance and coaching is very important. This would also be the place where they may need a little benzo to help them cope with the exit plan.

Side effects

Another common problem with ketamine is that it is given too quickly. Side effects can be minimized by giving the appropriate dose slowly. Analgesic doses can be mixed in some saline and given over 10 or more minutes to minimize the risk of side effects and prolong the analgesic effect. Dissociative doses should be given intramuscularly (probably preferred in most combative/agitated patients) or very slow IVP (over 2 minutes is best) to prevent the big, bad side effects like apnea. If you are going to use ketamine as a continuous sedative after intubation, for instance, you can consider setting up the infusion and giving the initial bolus from the pump. This not only frees up a set of hands but ensures safe timing of the initial bolus (2 minutes is always longer than you think!) Nausea and vomiting are the most common side effect and, although studies have estimated the NNT between 6-9, it may not be unreasonable to provide prophylactic ondansetron. If you are giving dissociative doses, you must be prepared to appropriately monitor the patient and treat apnea, laryngospasm, and hypersalivation, and provide advanced airway management.

Safety record

Ketamine has received a lot of negative press, but the truth is that it's a safe drug when used appropriately. Fernandez, et al. (2021) reviewed prehospital ketamine administration in over 11,000 patients, looking for hypoxia, hypercapnia, and mortality. They could not exclude ketamine as a contributing factor in only 8 deaths, representing just 0.07% of those who received ketamine. If you operate in the prehospital world, there is a great joint position paper out there on care and restraint for the agitated or combative patient from the NAEMSP, NASEMSO, NEMSMA, NAEMT, and APA (2021).

The bottom line: When used correctly, ketamine is safe and certainly our friend!

Do you want us to educate your team on the safe, effective use of ketamine? Black Cloud Solutions has a team of experienced, professional staff available to give presentations, help you design amazing clinical and leadership development programs, serve as an expert witness or provide other subject matter expertise, and assist with anything else you can think of. Contact us today!

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