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Do The White Right (propofol isn't the devil)

Early in my paramedic career I remember being told that propofol was the “white assassin” and had no role in the back of an ambulance or helicopter. The common quotes bounced around the web like a beach ball at a NickelBack concert.

“You can either have a patient properly sedated or a patient with an adequate blood pressure.”

“Propofol is meant for dark and quiet ICU rooms.”

I would pick up patients who were on a propofol infusion and switch it out for ketamine in transport. It made sense to use a sedative that not only was sold as being hemodynamically stable, but also included analgesic coverage. This was the ultimate BOGO!

I started to realize that almost every facility would discontinue the ketamine and put the patient back on propofol upon arrival. It is not common to see patients in an ICU on a ketamine infusion. This meant the patient now had to come off the ketamine, receive a new loading dose of propofol, and then be started on the infusion. Was this really worth it?

Additionally, I found ketamines "analgesia" over-rated when given as a mono therapy for intubation. My patients still ended up needing slugs of fentanyl during transport.

When I fast forward to the way I conceptualize sedation strategies now, there’s a stark contrast. The beginning stages of my knowledge were not formed by anything but input from others. I hated propofol and dopamine before I even knew why..

Here’s why I am saying all this..

I recently came across a tweet from a medical conference stating: “propofol doesn’t work in helicopters.” I feel this is less of a problem with the surrounding ambience as it is with our understanding of pharmacodynamics. I figured I would do a quick blog on some thoughts I have regarding propofol in the transport environment. I started off my rant with a tweet.

Dosing

Propofol is dosed with an initial loading dose of 0.5 to 2 mg/kg. This loading dose will depend on your patients hemodynamics. I generally find 0.5mg/kg over 5-10 minutes is the goldilocks number.

Here is a quick graph I made to illustrate how long it would take to reach a loading dose of 0.5 mg/kg.

After the loading dose, I typically drop to 30 mcg/kg/min. This is obviously patient specific. 

It's important to note that in order to avoid hypotension, your loading dose SHOULD NOT be a rapid push. Our friend @ChillaPharmD who works as a PharmD (go figure) had some great insight on this.

 

"What if I already used a sedative agent that works on the GABA receptors?"

Within the GABA receptor are subtype receptors that all circle around a chloride channel. Imagine a rose petal, and in the center of the petal is the chloride channel. Midazolam, etomidate, and propofol all work on different sites within the GABA receptor. Not to mention Ketamine works on the NMDA receptor which blocks excitatory stimulus from glutamate. When activated, chloride will pass through the channel and further drive down the action potential. This makes it harder for a messenger coming across the synaptic gap to trigger a stimulus. Here's an illustraton I created for a segment we did discussing this in the FOAMfrat refresher.

If other sedatives or analgesics are onboard, you may consider reducing your dose of propofol. This is where liberal dosing of analgesia allows conservative doses of sedative. The insert for propofol recommends the following:

"So I load with Propofol, start an infusion, and then I’m good — right?"

Propofol doesn’t do crap for analgesic coverage. The goal should be to optimize analgesic therapy to make the patient comfortable and then use a pinch of sedation to relax anxiety from noxious stimuli (I also highly recommend ear muffs as a non pharmaceutical means).

Propofol and Fentanyl

In my opinion these two agents should always be given together. If the patient has a long term paralytic onboard or shows any signs of discomfort I typically do something like this.

1. Show up at bedside - 100mcg fentanyl 

2. Make sure the ventilator is not set on some torcherous setting and that the foley bag is draining properly (two things that have bit me in the @$$ when it comes to patient comfort).

3. The Propofol tends to stay anywhere between 30mcg/kg/min (if no loading dose was provided, I may bump to 50mcg/kg/min per the chart above.

4.Minutes from short final - 100mcg fentanyl 

 

Summary

Propofol can be very effective in transport medicine if properly dosed and coupled with an "analgesic 1st" approach. As mentioned above, there is always risk of hypotension with ANY central nervous system depressant. The dosing and understandings of how each of your tools work will be your best guide to adequate and safe sedation stewardship.

When you think propofol... think fentanyl.

-Tyler Christifulli

References:

Diprivan Insert 

Propofols Role In The ICU

Propofol In Sick Cardiac Patients (Dose low and slow)

EMCrit on Propofol and Post Intubation Sedation

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