What Agent Should I Use For Procedural Sedation?

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Nurses Edition Commentary

Lisa Chavez, RN and Kathy Garvin, RN
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Suneth J., Dr -

I am an emergency physician working in Australia. I really enjoyed Rueben Strayer/ Rob Orman s segment on procedural sedation. Any thoughts about the best agent/ dose to sedate a conscious patient for DC cardioversion of an unstable tachyarrhythmia? (e.g rapid AF with hypotension/ Conscious VT). Propofol isn't ideal due to risk of hypotension. Ketamine not ideal, as could worsen the tachyarrhythmia. We don't have etomidate in Australia. Is this a time when the old Fent/Midaz has a role? Or is Ketamine safe in patients with tachyarrhythmia? Or would a small dose of propofol be ok? Thank you!

Reuben Strayer (@emupdates) -

Hi Suneth. This is one of the classic PSA questions and you've framed it nicely.

If very unstable, peri-arrest - just shock.

If unstable/hypoperfused/very hypotensive, etomidate is probably the best option but if you don't have it, ketamine. ketamine is unlikely to cause trouble here (at least from a hemodynamics perspective) because it does not cause significant catecholamine effect in patients who already have high catecholamine tone. you can't use propofol in this scenario, and these patients are too sick to be messing around with fentanyl/versed, which will also cause a significant sympatholysis which these patients may not tolerate.

if stable or semi-stable, propofol is the right drug, because of its super-brief duration of action. if you're concerned about the BP, you can push some phenylephrine or titrate up a drip to get their MAP up before giving the propofol, but in a well patient with arrhythmia-induced hypotension, since you're going to solve the cause of the hypotension with cardioversion, in my opinion you're generally safe to push propofol.

reub

Suneth J., Dr -

Hi Reub,

Thanks so much for the quick reply!

I have pondering this question for a while, and you have summarised a fantastic approach. I think its one of those situations where its good to have a pre-planned approach. So my options are from sickest to least sick - 1. nothing, 2 Ketamine, 3 phenylephrine (or metaraminol as we use commonly here) + propofol.

Any comment on the doses? Particularly for ketamine for the very hypotensive.. would you go for 0.5mg/kg (or less) or stick with 1mg/kg? I imagine a sub-dissociated state with people shouting "all clear" followed by an electric shock may not be very pleasant! However I imagine the full 1mg/kg may result in further instability from sympatholysis.

Thanks again!
Suneth

ps - loving the sense of humour in your segments
pps - Rob Orman's Kenny G joke had me laughing out loud!

Reuben Strayer (@emupdates) -

Suneth - Ketamine acts differently than a conventional sedative and using a subdissociative may not be any safer than using a dissociative dose. Since the sedation efficacy of subdissociative dose is unpredictably inferior to the dissociative dose(might be equal, might be tremendously inferior/dangerous, and how inferior cannot be predicted), I recommend a dissociative dose, which is ≥1 mg/kg IV or ≥5 mg/kg IM.

reub

Reuben Strayer (@emupdates) -

This meta analysis with James Miner editorial at the end endorse ketofol in this group. https://goo.gl/bmzTdV

Ed B. -

Hi Reuben,
Thanks for an excellent podcast!
I totally agree with your approach to procedural sedation, especially the use of low-dose Propofol to mitigate the adverse effects of Ketamine. I’ve been doing this for a few years now and I would highly recommend it.

My procedural sedation cocktail is very similar to yours:
- Reassurance and explanation to patient and family re what to expect from ketamine. I encourage family presence in the room if they are a calming influence. I also close the doors / curtains and try to lower noise levels to minimise over-stimulation.
- Fentanyl 1mcg/kg around 3-5 mins prior to the procedure. The analgesic, euphoric and anxiolytic effects of the opiate give a nicer “trip” with ketamine.
- Ketamine 20-40mg as a test dose. Some patients (eg. elderly patients) may have adequete sedation in this “recreational” dose range for minor procedures. Allows me to pick up patients who are unusually sensitive to the ketamine before I commit to the full dose.
- For everyone else, I titrate the ketamine up to 1-1.5mg/kg to achieve full dissociation.
- I use low-dose Propofol boluses (20mg) to manage agitation, hypertension or muscle rigidity during the procedure. I use Propofol for top-up sedation during the final stages of the procedure to smooth out emergence reactions and for its amnestic and antiemetic effects. I’ve found that the quick-on/ quick-off pharmacokinetics make it superior to midazam for controlling emergence reactions. I have also used Propofol in higher doses (50-100mg) to successfully manage ketamine-induced laryngospasm.

Having had some disastrous emergence reactions from ketamine as a single agent I now always pre-load with fentanyl and keep a vial of Propofol in my back pocket.

Hopefully after listening to your podcast, more people will start using this approach!

Cheers,

Ed Burns
Emergency Physician
Sydney, Australia
Medical Author
www.lifeinthefastlane.com

Reuben Strayer (@emupdates) -

thanks Ed. the pearl re: laryngospasm is an interesting one. I don't have the patience to titrate ketamine and have found that a fully dissociative dose is safe and effective for everyone, but many swear by the incremental approach you describe.

Ed B. -

Hi Suneth -

For the unstable patient with AF/flutter/VT and low BP (eg. 70-80 systolic), I would recommend:

- Take 5-10 mins to optimise the patient. You rarely need to shock them “right now” if they have a BP of 70-80 and are still conscious.
- 500ml saline bolus to boost preload.
- Fentanyl 0.5-1mcg/kg in small increments around 5 mins prior to the procedure. Fentanyl is very cardio-stable and doesn’t usually drop BP by much in these doses.
- Ketamine 0.5-1mg/kg (less than the 1-1.5mg/kg used in non-shocked patients). Give it slowly and stop as soon as you get dissociation.
- You can use 0.5-1mg boluses of metoraminol at any stage if the BP is falling below your comfort zone. This may not be necessary though.. the shock is a potent stimulus and many patients end up hypertensive once their rhythm is corrected.
- If they are tense and agitated after the shock you can use 20mg Propofol for additional sedation and amnesia (provided adequete BP).

I don’t usually worry about the sympathomimetic effects of ketamine driving up the heart rate. Most of these patients are already sympathetically maxed out, so you’re not going to be able to drive the HR much higher by using ketamine (you might get a BP spike though).
Also, for re-entrant rhythms like VT, the heart rate is determined by the length of the re-entrant circuit rather than by the degree of sympathetic tone, so the ketamine shouldn’t increase the heart rate.

Cheers,

Ed Burns

Reuben Strayer (@emupdates) -

Great points Ed. The heart rate pearls are key.

Suneth J., Dr -

Thanks Reub and Ed! The case that comes to mind was an elderly lady who presented a few years ago with AF broadish QRS and very fast HR - around 220. I was concerned at the time about AF with WPW (but later discovered it was AF with Ashmann's phenomenon - which I had never heard of before). She was hypotensive (~80 systolic), but conscious. The added issue was that I wasn't sure that the cardioversion would work (unlike VT for example). and indeed it didn't - despite 3 x shocks, and we ended up rate controlling with amiodarone.

For the cardioversion - I ended up sedating her with fentanyl and small boluses (0.5mg titrated) of midazolam - but didn't feel that the sedation went as smoothly as I would have liked, and there was probably some awareness, which I understand isn't the most important thing, but I would have liked to avoid if possible.

Would a fentanyl/ ketamine/ metaraminol combination have been safe in this situation as well? (given the non re-entry circuit tachyarrhythmia). Also any thoughts about the concern of using ketamine in an elderly patient with CVS disease?

Thanks to both of you so much for your valuable input!

Reuben Strayer (@emupdates) -

unstable elderly person requiring cardioversion is tough PSA scenario. i think you are unlikely to effect adequate analgesia/sedation in an elderly woman needing an extremely painful procedure like cardioversion using fentanyl/versed without flirting with apnea/worsening hypotension. etomidate is probably the best option. if you don't have access to etomidate, I would use ketamine monotherapy. No reason to add fentanyl if you're using dissociative-dose ketamine. Be ready with vasopressors and be prepared to intubate.

ThanhVan T. -

I am an emergency medicine physician and medical director in a busy ED in a small, rural hospital. Before our group started in this hospital, the hospital had a procedural sedation policy that required 2 providers to be present during a procedural sedation if propofol was to be used. That is, there needed to be a provider present to do the sedation, and another provider (whether it's a CRNA, another physician, etc) to do the procedure (like a joint reduction, laceration repair, etc). We thus used mainly etomidate, ketamine, etc at this small hospital. Our group of 20 physicians also mainly practices in a larger hospital, in a nearby larger town. Many of the physicians expressed an interest in being able to use propofol in the this smaller ED as we are allowed to do so in the larger one. The 2 hospitals are not affiliated.

So, in my efforts to change the sedation policy regarding propofol at the smaller hospital, the administration (who are not physicians) have decided that all procedural sedations, regardless of agents used, require 2 providers. This puts us in a pickle as we are single coverage. As a result, we need to call in the CRNA to do the sedation, who are not always in house. I've provided the administration with the ACEP guidelines, and have provided guidelines similar to our larger hospital, which is similar to other hospitals that I have practiced. (I've also been on the coreem.net site.) We are all board certified emergency physicians, and do this routinely at our other hospital.

Are there a lot of hospitals that are requiring this 2 provider policy? Is this the future?

Reuben Strayer (@emupdates) -

I'm hoping this is more of the past than the future.

Perhaps the best way to address this is, after providing the data/guidelines demonstrating that one-provider PSA is safe and accepted practice, document cases where patients suffered harm because a second provider wasn't available.

Another tactic is to propose that one-provider PSA be implemented provisionally, and every case will be reviewed, for 6 months, and at that time it can be decided whether or not there is a safety concern and the practice should be extended.

Can be very difficult to affect change in these ways; the hospital administrators are responding to their own incentives which are often not patient- or physician-oriented.

good luck
reuben

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