FOAM readers will have come across Michelle Lin and her Academic Life in Emergency Medicine blog and Tricks of the Trade spot on EMRAP. Recently she has been spruiking the “Dirty Epi” drip in anaphylaxis.
The idea is, when the patient fails to respond to two IM doses of adrenaline and you are looking at switching to IV everything is usually happening pretty fast. You really want that adrenaline up now, not in 5-7 minutes time, which is what it can take for a 6mg in 100mL to be made up and countersigned and a pump found and so on. So, while the nurses are scrambling for that, put 1mg of Adrenaline of any concentration into the bag of Normal Saline that has likely just been hung and just let it run in, titrating to effect. It will give 1mcg/mL and will run at about 20-30mL/min so you’ll be giving 20-30mcg/min which is a pretty good starting dose for IV adrenaline in refractory anaphylactic shock. Of course, you might have to titrate to effect by tightening up the little roller clamp or squeezing the bag but you titrate an adrenaline infusion to effect anyway.
The trouble is, how often do we see refractory anaphylaxis? So I read about it and thought, well, that’s great but I’m not going to use it.
Then comes the middle aged, not terribly well preserved man with hyponatraemia of uncertain cause, left lower lobe pneumonia, septic shock and respiratory failure who needs a tube. BP falling just as the need to get on and intubate becomes apparent. No pressors up yet. Arterial line quickly inserted shows BP 60/20. Bother, that’s a bit lower than the NIBP was showing. This looks like a perfect opportunity for one of Scott Weingart’s Haemodynamic Kills. No time for a formal pressor infusion to be drawn up. I pull out a milligram of adrenaline to make up some dilute “push dose pressor” and a little voice in my head says “try the dirty epi drip”. There’s a full bag of fluid just been hung, running into a good ACF vein via an 18g cannula. Perfect.
With the arterial line in it was a piece of cake to titrate the flow of adrenaline-saline with the roller valve while keeping an eye on the registrar’s intubation and the resident’s (frugal) dosing of induction agents. To get the BP up initially required a couple of squeezes of the hand pump on the resus giving set but the BP quickly came up to where I wanted it (120/70 ish) and never dropped below 90/60 for the duration of the intubation process.
I actually think it is safer than fiddling around calculating concentrations and doses for “push dose” adrenaline, a process that carries a high risk of giving too much by a factor of 10. The main caveat would be that you need to be prepared to run in a litre of fluid. If your patient is shocked and being intubated a litre is probably neither here nor there but there may be cases where you really couldn’t afford the volume.
For now though, I’m a convert. Thanks Michelle!
PS: I should add, this is a hands-on activity. You can’t make one of these up, set it running and go do something else. Consider it a big syringe full of dilute drug. Once the dust settles, take it down and replace it with something you can run hands free though a pump.