The Story
Ben McKenzie, an emergency physician in Australia. His son, Max, died from anaphylaxis as a 15 y/o. PMH asthma, walnut allergy. He ate apple crumble with ground walnuts. He used his epi pen and EMS was called. Max told medics he was having anaphylaxis. He arrested after 2 doses of IM Adrenaline. He got IV adrenaline after arrest, got ROSC. His GCS was 3 on arrival at the ED, BP was good. His respiratory status required BVM ventilation. He was being ventilated without ETCO2. He had an extended resus without intubation or FONA. Ben arrived to find Max in asystole. He had to take over care and directed surgical airway. Ben had to put his finger in the hole to put bougie in. Max regained pulses in 2 minutes, but had already sustained devastating hypoxic injury.
Similar to Martin Bromiley with his wife Elaine, Ben, instead of pursuing punitive recourse, wanted to change the world into one in which Max's case would never happen again. He has put all of his efforts into creating and teaching the AMAX4 protocol.
On Ben's site, he also tells the story of James Tsindos died at 17, IV epi 13 minutes post-arrest, intubated 17 minutes post-arrest
AMAX4 Site
AMAX4 Algorithm
If you are a resuscitation doc, listen to my podcast, if you are a non-resus doc, listen to Ben's
A – Adrenaline
1mcg/kg intravenously push dose every 30 seconds to 10 minutes or cardiac arrest dose
M – Muscle Relaxant
First and only attempt at laryngoscopy must be best attempt
A – Airway – ETT
With working cuff to successfully oxygenate with high airway pressures. Mask and LMA unsuitable
X – Xtreme Care
Xtreme obstructive ventilation
Xtra bronchodilators as required
Xtra vasopressors/volume as required
X PneumothoraX
4 Minutes
Max 4 minutes until definitive airway and ventilation (oral ETT or FONA) to avoid brain injury
AMAX-4 Lecture Page
Anaphylaxis
Most young people with anaphylaxis die from bronchospasm – especially food allergy which is the most common trigger presenting to ED. Bronchospasm also occurs in drug and venom allergy and causes death in young people. This algorithm covers all bases.
EPI
5-8 minutes for IM epi to work in extremis
20 mins for subcutaneous
Consensus from Anaphylaxis Community
if you need more than 2 doses IM q5 , give IV
Disagreement
Dilution is wrong way to go
I say just give 0.5 mls of cardiac epinephrine
10 Concepts on Oxygenation in these Patients
1. Time to Hypoxic Brain Injury is 4 Minutes
Brain dies after 4 minutes at sat of 40% (PaO2 29). LOC happens at this sat, so max 4 minutes after LOC from anaphylaxis or asthma.
this is not an indication to take the 4 minutes–in many patients there will be far less time
2. Airway Pressures are HIGH in arrested asthma/anaphylaxis
Need a cuffed ETT and either a BVM or a pressure unlimited vent with ETCO2
ETT is the only exit from the Vortex/only path out of failed airway
if you have ETCO2 then LMA and BVM can be a bridge
Vent and bvm are the same thing, move to asthma mode, pressure limit to 100
LMA is a great move after you have made the decision to perform surgical airway
Monitor ETCO2
3. Immediate Securement with ETT has numerous other benefits
Intubate early, extubation is much safer than late intubation
Aspiration risk is high and consequences catastrophic
In many cases, an earlier intubation should have been performed awake before progressing to this point
4. First Attempt Should be the Best Attempt
give muscle relaxant
stop cpr
best intubator in the room
do not wait for sedation if pt is in arrest
best intubator in the room
In ED intubation meds should already be drawn up, in ICU, anesthesia usually already has it drawn up
5. One Attempt at Intubation Only
Controversy–should it be the only??
This is the one you need to make common knowledge throughout the medical system
6. You do not need any other Cognitive Push than 1 missed Intubation to move to FONA
Move the padding from the head to the shoulders
Ventilation should continue during FONA
See EMCrit Cric Page for far more info
7. Get Good at Intubations
have a crash intubation
the reason we checklist in most patients is to build the crash intubation muscle for the very rare case like this
talk about checklists
8. PneumothoraX Rates are High in Arrested Patients
but not if you ventilate well
BVM causes this
9. Extreme Ventilation
medical therapy for bronchospasm
Max out the PIP Limit
Lateral Chest squeeze (assisted exhalation)
10. Extra Medical Therapy
Ventilation
- bronchodilators
- ketamine
- inhaled anesthetics with AdaConDa
- consider VV ECMO
Hypotension/Shock
- epineprine infusion
- norepi
- methylene blue
- vasopressin
Other Sites' Takes
Additional New Information
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Dear Scott and Ben:
I would love to learn about the dosing/type/route of muscle relaxant in a crashing anaphylactic patient! Titrating up dosage seems reasonable to me considering shock status, but should I alway use maximum dosage? IM route may be an alternative. But in “4 mins”, i wonder what is the trigger to go IM instead of waiting for establishing IV?
Thanks!
The muscle relaxant eg rocuronium 1.2mg/kg is a fixed maximal dose to ensure your one and only attempt is the best attempt at oral intubation. It is the only drug you technically need to intubate. No titration. Totally maximal dosage rather than 0.6mg/kg. It needs to be in your resus trolley so it is available at short notice. Not locked away. I totally get what you are saying if there is no IV access. IO or IM in the short term (first minute) is fine but you are going to need some vascular access in these patients. If the patient… Read more »
Thanks for all these precious feedback! Great lesson
Just Want to Share: one of sickest cases ever was anaphylactoid reaction to IV contrast. BP 60/nothing after IM, then IV EPI, EPI drip. Dumping IVF. Losing airway but wanted to prevent peri-intubation arrest so we were maxing out EPI and IVF. When it was reaching critical airway edema BP >80, I intubated and there was no cardiac arrest. POST intubation, recurrent hypoxia would occur and we would roll pt to her side and clear fluid LIKE A SPIGOT would spill out of ET tube. We would repeat this cycle for almost an hour till she went to ICU. (still… Read more »
Pediatric bag valve mask to lessen PTX risk
Hi Scott
Would love to hear your thoughts on the volume Resus required and the potential for SAM in fit young hearts receiving large dose adrenaline…. Is this a concern?
Anaesthesia teaching is to give a lot of crystalloid to fill the venous side but is it actually possible in time or are pressers a better option in that 4 minutes?
The amax4 algorithm doesn’t say much about volume ?
I think that it is worth saying that a lot of self-inflating bags have pop-off valves that can be closed, but by default are open which can prevent the delivery of adequate pressure in severe bronchospasm, even with a cuffed ETT in place. They all (at least all of the ones that I know) can be closed very easily by flipping a clip or inserting a plug but have been known to get overlooked in the heat of the moment. So, if the ETT is in (via whichever route) and you’re still not able to move the chest or get… Read more »
Hi Scott, thanks for another awesome episode! I would like to push back on the “checklist detail” though: I think the more time sensitive the situation gets, the more the checklists are needed. In his book “The Checklist Manifesto” Atul Gawande describes what happened in the cockpit of the flight that landed on the Hudson river. Interestingly the timeframe they had for their decisions ranges from 3.5 to 4.5 minutes and Sullenbergers co-pilot went through several checklists during that time and the plane could be landed safely. So I would argue that we need the “right” or “good” checklists for these… Read more »
we’ll have to disagree on this one. As someone who is the biggest proponent of checklists you will find as this podcast demonstrably shows–this is not the time. Most of the items on the checklist are completely obviated by the situation and in fact they will actually send you astray. Just one example: 3 minutes of denitro demanded by our checklist will be life threatening in this circumstance. This is the quintessential situation in which you yield the benefits of years of checklisting in order to transcend the need for the checklist. Similar to Josh Waitzkin’s concept of form to… Read more »
Hi Scott,
I think it bears mentioning that the standard 7 inch IV “extension tubing” that is almost universally connected to the IV catheter that is inside of the patient will itself hold approximately 0.69ml of fluid (at least, the ones I have at my shop do according to the packaging), so, if you’re going to give the 0.5ml of cardiac Epi, it is imperative to remember to follow it with a flush so it doesn’t just sit inside of the extension tubing doing nothing for your patient.
Best,
DW
Hey Daryl, We have gotten this comment a lot and it is absolutely true. However, I don’t understand, are people not routinely flushing–every med we give should be flushed. I have heard people say if you are injecting into a running line, maybe you don’t have to flush, but even then it seems silly–I flush everything.
Agree. I flush everything as well.
Anecdotal, of course, but what I tend to see is that nurses seem to be really good at flushing meds, however, it gets forgotten when the meds are given by a doc unless an astute nurse hands them a flush to remind them. Thanks for another great podcast.
I am confused as to why Diphenhydramine is not part of this algorithm.
because it really doesn’t do anything
Great lecture.