Ketamine... its role in emergency medicine should go together like baileys and coffee…and yet when I mention even just the name in the emergency setting I get cringes from every healthcare provider imaginable… nurses, medics, and especially residents. In fact the only people I never get a such a reaction from are from those who actually understand Ketamine’s pharmokinetics and amazing versatility…the ED pharmacists (@theedtraumacist)!
Ketamine was first synthesized in the 1960’s from Phencyclidine (PCP) and was FDA approved in 1970. Thereafter it was used medically during the Vietnam war to induce anesthesia mainly due to its shorter duration of action, less side effects as compared to PCP, and most importantly, minimal effect on respiratory drive. This allowed invasive procedures and surgeries to be performed almost anywhere without the need for hemodynamic monitoring and respiratory equipment, ideal for the jungles of Vietnam then, and developing countries now.
Ketamine blocks the NMDA receptor which causes the central nervous system to lose responsiveness. At low doses pain relief, slight amnesia to event, and alteration of the perception of sight and sound occurs. Moderate doses start to create an ‘out of body experience’ with mild paralysis and short-term amnesia in what we call ‘the K-Hole’ and at high doses, it causes near-complete paralysis, amnesia, and sedation, yet with preservation of respiratory drive and rather than a decrease in HR and BP like most sedatives…it increases them!
Today, most negative opinions of the drug originate primarily from its common use as a horse tranquilizer, its heavy use as a club drug in the 90’s and early 2000’s, and its propensity to cause severe hallucinations. In fact, mention ketamine to any ER nurse and most will groan and tell you a story of a patient that “had a bad trip”.
Despite these negative connotations, the WHO still lists Ketamine as an “essential medicine and among the safest and most efficacious one known to science”…mic drop bitches.
Let’s explore some reasons on why that is.
First Ketamine is cheap, and I mean really cheap. In fact, an entire VIAL at wholesale ranges between 84 cents and $3.22 (dependent on amount ordered and concentration). Still if you have ever used Ketamine you know you use maybe a 1/5th of the vial on a single patient and then you toss it. In developing countries that one vial could be used for 5 patients making it an even cheaper drug.
Ketamine is extremely stable and user friendly. It doesn’t froth up in an emergency. It doesn’t have to be refrigerated nor covered from light, its dosing is easy to calculate, it can be given via almost every route imaginable…intravenously, intraosseously, intramuscularly, subcutaneously, epidurally, intranasally, sublingually, rectally, and orally. It’s also surprisingly hard to kill someone with due to its pressor qualities and its minimal effect on respiratory drive. In fact, I once watched a resident mistake a syringe full of ketamine for a flush and push the entire thing intravenously on a patient. That’s right, 500mg of ketamine on a 60kg adult who already had fentanyl on board from EMS. Side note: never forget that nurses really do keep doctors from killing you, and this is why you will rarely see docs pushing medications…ohhhh July 1st. Anyways, the patient, aside from having to be monitored through what must have been the most epic K-hole trip in history, thanks to its short duration of action, was fine after about an hour. No need to intubate, no need to give pressors. Tell me what other sedative or analgesic you could do that with?
I touched on this earlier, but Ketamine is an austere-environment anesthetic in that it can pretty much be used in any place, at any time, in most situations. Stemming from its inception as an anesthetic in the jungles of Vietnam, Ketamine is used today in many third world and developing countries where anesthesiologists, ventilators or hell… even electricity may not be a luxury the facility (or hut) has. In developed countries Ketamine is also useful to pre-hospital and transfer providers. Ever try to intubate in the back of an ambulance? How about in a cramped helicopter? Its not simple, hence why most pre-hospital providers would rather intubate on scene then wait until the patient acts a fool in route. Ketamine eliminates the need to intubate patients for pain control or agitation (***not airway compromise***), thus eliminating the need to setup a ventilator. Side note for non-prehospital folks: when a patient becomes agitated in the air, there are no second chances, you put the patient down or you all go down. It seems aggressive but all it takes is a patient to kick the wrong button, lever or pilot for you all to be in some deep shit. Sorry not sorry.
It’s a great trauma analgesic. Patients who have been shot, blown up, hit by cars, fallen from significant heights or found themselves in severe MVA/MCCs are not easy patients to transport from a scene, and many times they are hemodynamically unstable. Ketamine will not only calm a patient as mentioned earlier and numb their pain, but decrease complications in ‘load and go’ scenarios, which means less time on scene, quicker transports and thus increased chance of survival. And because it increases blood pressure, you just gave them a pressor that along with blood/fluids can’t hurt.
1. As an analgesic Ketamine can be given via slow IV push with a dose ranging between 0.1-0.3mg/kg. This can also be given via my favorite route, infusion, for those chronic pain patients (Sickle Cell, Gastroparesis, Fibromyalgia, severe migraines, phantom limb pain, SCI, and idiopathic pain). A common way to do this is 0.3mg/kg in a 100ml NS bag over 15minutes. Not only does this lengthen the treatment window, but studies show that giving Ketamine slowly actually decreases emergence phenomenon and ‘bad trips’.
Also Administering Ketamine to a patient with a severe trauma or injury can actually decrease the occurrence of him/her developing PTSD to the event later in life. Personally, if my leg was ripped from my body in a traumatic event, I would prefer to not mentally be aware of the situation…just sayin.
2. As a moderate (conscious) sedation drug for use in procedures such as reductions, chest tube insertions, wound repairs, and invasive pediatric procedures like laceration repair, Ketamine can be given 0.5-1.0mg/kg IV or 4-5 mg/kg IM.
This a great drug for pediatric patients in need of invasive procedures ranging from foreign body removal to suture repair. It is also great if IV insertion is necessary and the child cannot be calmed. Why poke a child 6 times and put them through unnecessary emotional and physical trauma, while also putting yourself and other at risk of a needle stick injury? Put the child down and not only will you have time to look for an appropriate IV site, but the child wont thrash or even remember the event.
3. For deep sedation, anesthesia, and RSI Ketamine can be given at 1-5mg/kg IVP or 0.5-2mg/kg if an adjunct drug such as midazolam is used to prevent emergence phenomenon (which I am a huge advocate of).
Maintenance dosing is just half of the IV ketamine induction dose administered as needed or 0.1-0.5 mg/min IV continuous infusion.
If a line cannot be established then 6.5-13 mg/kg IM one time can also be given
***note dosages and uses can vary based on hospital policy and/or region***
There are many off label uses for Ketamine too! Hundreds of studies have been concluded and are underway establishing Ketamine’s role in the treatment of severe depression, bipolar disorder and suicidal ideation. It has also shown in numerous trials to cure severe PTSD in patients that had slow Ketamine infusions along with therapy sessions. And it’s being used in the treatment of severe alcohol withdrawal to lessen the high dosages of benzodiazepines needed and decrease side effects/dependence! Oh and it plays a role in the treatment of severe asthma due to its effect as a bronchodilator combined with its ability to lessen anxiety.
So why the widespread negativity!?
Well, what these groaning providers don’t realize is most of the time the drug isn’t given correctly. First, prior to and during administration, the patient (especially children) should be walked through pleasant memories. For the most part, if they fall into the ‘K-hole’ happy, they rise happy. Second, to minimize possible emergence phenomenon or ‘bad trips’ patients can be pre-medicated with a benzodiazepine (Midazolam is the favorite). This can also decrease the pressor effect if so desired.
Now this is a wonder drug but that doesn’t mean it is without its demons. Ketamine can cause some nasty hallucinations in some patients, even despite pretreatment, but the incidence is quite low when given correctly.
Ketamine also has no reversal agent, so time is your only antidote. This rarely is a problem though due to the drugs quick mechanism of action and short duration.
Ketamine can also cause hypersalivation, this is predominately seen when given IM in children but can occur via any route at any age. This is generally prevented by giving an antisialagogue such as Atropine as an adjunct.
But Perhaps the most concerning, sphincter tightening, piss your pants issue is possible laryngospasm. This is a rare adverse reaction, occurring in less than 0.4% of patients, but is heavily correlated to IV push Ketamine use. There are times one can ‘break’ the laryngospasm or wait out the episode by bagging with CPAP and a modified jaw thrust maneuver, but more than likely in the emergency setting, the patient will be given paralytics and intubated. Scary yes, but rare.
So, if you haven’t realized by now, I am a huge advocate of this drug. In fact, if you’ve ever worked with me, you have grown tired of how often I suggest and hype this drug up to my fellow RNs and Residents. I can routinely be heard suggesting “30ml in a 100ml bag over 15min” for that uncontrollable sickle celler or that opiate addict with a broken arm. And most of the time I’m scoffed at. But I still do it. As an RN I must do my part to advocate for my patients and suggest treatments that would be beneficial. Whether or not the physician decides to consider my advice is on them, but I will always be there to suggest it. With all of the research, increased use, and positive press in the last few years, I am willing to bet Ketamine becomes a much bigger staple in the physician’s tool box in the coming years.
Conclusion, if you’re an Emergency MD, place this drug in the forefront of your treatment lineup. If you’re a pharmacist, keep educating, and if you’re a nurse or medic, advocate, suggest, teach and learn.
1. Feder A, Parides MK, Murrough JW, et al. Efficacy of Intravenous Ketamine for Treatment of Chronic Posttraumatic Stress Disorder: A Randomized Clinical Trial. JAMA Psychiatry. 2014;71(6):681-688. doi:10.1001/jamapsychiatry.2014.62.
2. Heinz P, Geelhoed GC, Wee C, et al. Is atropine needed with ketamine sedation? A prospective, randomised, double blind study. Emerg Med J 2006; 23: 206–209. [PMC free article] [PubMed]
3. Howes M C. Ketamine for paediatric sedation/analgesia in the emergency department. Emerg Med J 200421275–280. [PMC free article] [PubMed]
4. Li L., & Vlisides P. E. (2016). Ketamine: 50 years of modulating the mind. Frontiers in Human Neuroscience, 10, 612 https://doi.org/10.3389/fnhum.2016.00612 [PubMed]
5. Morgenstern J, "Managing laryngospasm in the emergency department", First10EM blog, March 3, 2016.
6. O’Carroll D, MD, “Why Ketamine Is the Best Drug on Earth: An emergency-room doctor explains why he routinely sticks his patients in the K-hole”. Tonic Vice Article, Mar 1, 2017
7. Perumal D. K., Adhimoolam M., Selvaraj N., Lazarus S. P., Mohammed M. A. (2015). Midazolam premedication for Ketamine-induced emergence phenomenon: a prospective observational study. J. Res. Pharm. Pract. 4, 89–93. doi: 10.4103/2279-042X.155758 [PMC free article] [PubMed]