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Ketamine for primary care providers in remote medicine

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Ketamine for primary care providers in remote settings
By Dr Minh Le Cong
MBBS, FRACGP, FACRRM, FARGP, FACAsM, GEM, GradDipAeroRTM
Disclaimer : I have provided the recommended dosages of medication and preparations as a guide only. Final decisions on dosing and drug preparation must be your own responsibility as a medical/health practitioner working within your nation’s laws and professional scope of practice.

Indications
-acute sedation for painful procedures
-acute analgesia for moderate to severe pain not responding to opioids
-emergency general anaesthesia

How to prepare an injection, different concentrations, how to dilute
Ketamine hydrochloride comes as a clear liquid in dilutions of 50mg/ml or 100mg/ml. Typically a 200mg in 2 ml ampoule is available. It can be given undiluted for intramuscular administration or mixed with normal saline or dextrose solutions.

When to give iv vs im. Where to give. How to give. What not to do.
Intravenous administration is preferred, in particular if repeated dosages are expected. Slow IV push is preferred as rapid bolus can lead to apnoea. Preparing a ketamine drip by injecting 500mg into a 1000ml bag of saline will allow a gravity fed infusion to be started for general anaesthesia.

Intramuscular or intranasal administration is reasonable for short procedures when repeated doses are not expected to be required or if intravenous access is difficult to gain initially. 5mg/kg IMI or Intranasal will provide adequate analgesia and some sedation to allow a quick procedure to be performed or the gaining of IV access. Intranasal ketamine must be delivered in an atomised spray or mist to be effective, otherwise it becomes an oral dose. Simplest way to produce a mist is to connect a 3 way tap IV connector to oxygen tubing then connect a 18G peripheral IV cannula to the distal connector and the ketamine in a syringe to the side port connector. Deliver 4 L/min O2 down the tubing and squirt in the premeasured ketamine via the 3 way tap. This oxygen flow produces a jet mist via the 18 G cannula.

Equipment and preparation.
Ketamine is an anaesthetic agent so care must be taken when administering it.

The basic setup for ketamine sedation /anaesthesia should be :
Bag/face mask manual resuscitator
Oral and nasal airways
Suction
Oxygen if at all possible
IV access equipment
Blood pressure cuff
An assistant for airway technique and monitoring assessments

It would be nice to have :
Oxygen saturation monitor
Cardiac monitor
Intubation drugs : suxamethonium, thiopentone, midazolam

. Contraindications. Adverse events, how to prepare and how to treat
There is good evidence to support the use of ketamine sedation in children and adults for emergency procedures. The use of ketamine anaesthesia in adults is extensive and its utility and safety in remote settings is well recorded.
Whilst there is no strict age limit to ketamine use as an anaesthetic, analgesic or sedative, many guidelines indicate the expert opinion of avoiding ketamine use below the age of 6 months for elective procedures. This is due to animal model research findings of neurodevelopmental abnormalities despite a complete lack of human evidence for such problems. In the event of emergency, life threatening cases, the balance of risk vs benefit in using ketamine for any age group must be weighed by the provider.
Ketamine will produce elevated blood pressure and pulse. Any condition that will worsen with such a change , one needs to be extremely cautious in using ketamine. For example, severe pre-eclampsia or aortic dissection will be seriously worsened by ketamine in the usual doses. Cardiac ischemia, angina and myocardial infarction may get worse with ketamine induced tachycardia and hypertension. This sympathomimetic effect of ketamine can be blunted with co-administration of morphine, diazepam, midazolam or droperidol.

Ketamine produces nystagmus and so is not ideal for ocular procedures. Hypersalivation is common but usually not an issue in short procedures. Longer procedures may benefit from an anticholinergic agent to dry secretions, atropine 300mcg in adult IV or 10mcg/kg IV in children.
Common adverse events also include nausea and vomiting with higher dosing range >;;;;;4mg/kg boluses.

The most serious adverse events are hallucinations/delirium and laryngospasm. Whilst uncommon they do occur and a provider must be prepared to manage them

Laryngospasm is the sudden spasming of the vocal cords and leads to acute airway obstruction. The patient will be making chest wall movements but no airway noise or a stridor indicating partial closure of the vocal cords. Immediate action is to provide positive pressure ventilation with oxygen via a manual bag/face mask resuscitator. A jaw thrust by an assistant will greatly help the alleviation of the spasm. If this does not relax the spasm then administration of IV (1mg/kg) or IMI(4mg/kg) suxamethonium should resolve the issue and allow emergent intubation to occur to secure the airway. If the laryngospasm resolves adequately to allow effective face mask ventilation then tracheal intubation maybe deferred if the procedure is short and the aim is to recover the patient quickly.

Emergency delirium/hallucinations are frightening perceptual experiences during ketamine sedation/anaesthesia and often occur during the recovery phase. They are uncommon as many experience complete amnesia with ketamine. To minimise the risk of their occurrence then co-administration of midazolam 1-2mg IV or diazepam 5mg IV is helpful. The same benzodiazepines can be used to treat emergence delirium as well. This problem is almost exclusively seen in adults rather than children.

low dose for pain control vs higher dose for sedation vs induction dose. compatability with other drugs like morphine, pethidine, propofol.
Ketamine is an excellent analgesic at low doses 0.5mg/kg IV. Sedation for procedures can usually be achieved with 1mg/kg IV dosing whereas induction and general anaesthesia doses are typically 2mg/kg with maintenance 2-4mg/kg/hr IV infusion. Ketamine is compatible with all other anaesthetic drugs and analgesics. It has an opioid sparing effect. Ketofol is an alternative cocktail of ketamine and propofol usually in a 1:1 ratio but increasingly providers use separate syringes of each and give small boluses of both drugs to provide a balanced form of anaesthesia/sedation. I personally see no advantage over plain ketamine.

How long will the effect last? Can you repeat?
IV ketamine will last 10-20minutes then require repeat dosing or an infusion to maintain. IMI ketamine will last 30-40 minutes depending upon the dosing. IV ketamine can be repeated multiple times. IMI ketamine you should not repeat unless absolutely necessary as it will lead to prolonged sedation and recovery. If you need to repeat ketamine after IMI dose, better to gain IV access and administer smaller IV dose

Long term side effects
The only recognised long term side effect of ketamine is in chronic abuse of the drug for recreational purposes. Daily long term use of illicit ketamine for recreation has lead to a significant number of users developing a chronic uropathy characterised by bladder wall dysfunction and lower urinary tract inflammatory symptoms.
There is no evidence that medical use of ketamine leads to this uropathy. Studies into the effects of ketamine on psychotic disorders have never revealed a long term increase in the development of chronic schizophrenia or mental illness as a result of ketamine.

References:
Ketamine, a review by a Medecins Sans Frontieres anaesthetist<;;
Basic ketamine infusion anaesthesia
laryngospasm after ketmine

15 Comments Post a comment
  1. Thanks Minh, useful post – like many rural docs, I’ve been using ketamine more and more in our small ED in recent years – changing burns dressings, performing short painful procedures – and trauma RSIs or (occasionally) DSIs

    Thanks too for the useful dosing IV – IM – IN

    A mate has played around with ketamine dissolved in Orange Juice (for a patient, I stress). I must ask him how that went…

    December 30, 2012
  2. Ben Hoffman #

    A great post Minh, very helpful for the “ketamine novice” I would imagine!

    Personal opinion only but oxygen saturation really should be compulsory; the small handheld or clip on SpO2 monitors are very inexpensive and reliable.

    Intensive Care Paramedics in New Zealand have administered ketamine over 2,500 times in the last 5 years for analgesia and anaesthesia with no adverse affects and only minor psychotropic side effects.

    By all accounts ketamine is a very safe and desirable medicine, especially in the pre-hospital and emergency medicine environments where patients often have some sort of physiological derangement which makes an agent like propofol, thiopentone or midazolam relatively contraindicated because of their negative cardiovascular or respiratory side effects.

    December 31, 2012
  3. Gerard Fennessy #

    Hi Minh –

    I am a great fan of using ketamine in the field, due to its safety profile, and excellent patient outcomes (generally). My best experiences were on a skifield with fractured tib/fibs, whilst the patient still had the ski-boot on. Removing the boot from a floppy tib/fib was inevitably excruciating, and for the patient too.

    We applied O2, a sats monitor, and hit them with 200mg of IV ketamine. As soon as the nystagmus started, we ripped the boot off – took an xray, straightened the leg, applied the cast, and the patient woke up 20 minutes later wondering what all the fuss was about. Excellent.

    One point I would like to bring up is the use of adjunctive benzodiazepines – my reading suggests that benzos confer no advantage (even over emergence phenomena – where a pre-ketamine “think of a nice place”, or a further dose of ketamine – seem to take care of the emergence), and offer the disadvantage of higher rate of desaturations. Is the jury still out on this?

    I never used benzos, and for emergence, I just gave them 50mg ketamine to settle them down, then reassurance.

    These references (from “Ketamine for paediatric sedation/analgesia in the emergency department. M C Howes. Emerg Med J 2004;21:275–280.”) seem to support no benzos.

    Sherwin TS, Green SM, Khan A, et al. Does adjuctive midazolam reduce recovery agitation after ketamine sedation for pediatric procedures? A randomised, double-blind, placebo-controlled trial. Ann Emerg Med 2000;35:229–38.

    Wathen JE, Roback MG, MacKenzie T, et al. Does midazolam alter the clinical effects of intravenous ketamine sedation in children? A double-blind, randomised, controlled emergency department trial. Ann Emerg Med 2000;36:579–88.

    Carley S, Martin B. Midazolam and emergence phenomena in children. Emerg Med J 2001;18:273–4.

    January 16, 2013
      • Gerard Fennessy #

        Ta Minh,

        My reading of the article still doesn’t convince me. 50 patients in each group. Both lost 5 to follow up (10%). Agitation was a binary thing, and not rated. Although pleasingly there appeared to be no desats in either group. I’m not sold… I think their conclusions (NNT=6) are optimistic.

        Anyway, I’m all for opening up the discussion for this cheap, underused and safe drug. Cheers

        January 16, 2013
      • thanks Gerard. I think you can do either way. ketamine by itself is usually ok but you cAn get some unexpectedly distressing hallucinations in some. you just need to be prepared for it.
        I agree that the concern about the emergence reactions is not a good reason to avoid learning how to use an effective agent for a variety of presentations and acute conditions. it is one of the more forgiving emergency drugs out there.

        January 16, 2013
    • Gerard Fennessy #

      Hi Minh,

      Like a Shakespearean dream, last night I had an additional thought. (and no, I’m not on the ketamine or benzos).

      What about the paradoxical reaction to midazolam? Is it as common as the ketamine emergence?

      Do you think there is any way to separate these two effects? I have seen it only twice but it’s impressive.

      January 17, 2013
      • HI mate!
        yes have seen paradoxical agitation in kids with midaz..like any sedative, underdosing can bring this out..it can be a fine line to walk

        also have seen paradoxical agitation as a result of severe akathisia from classic dopamine blocking sedatives like haloperidol..once again more common in younger age groups.

        but with ketamine its more than just feeling of restlessness and dysphoria..its clear patients can suffer distressing hallucinations..second patient I ever administered ketamine to for analgesia, felt she was levitating off bed and flying around room. Midaz settled it down very quickly and she had no recall of event.

        thats why I believe that Annals of Emerg Med RCT paper…it echoes my own clinical experience.

        Did you ever check out the Israeli Military prehospital paper ln ketamine and midaz sedation ?

        January 17, 2013
      • Gerard Fennessy #

        No, but would be keen to read it – do you have the link?
        And after all that, I think you have made a good case for having midaz ready and available. Thanks!

        January 18, 2013
      • Sure thing and thanks for comments !

        January 18, 2013

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