Just a routine resuscitation. The AMAX4 algorithm for anaphylaxis/asthma. St Emlyn’s

Estimated reading time: 6 minutes

This post is from Australia and was brought to us by Dr Ben McKenzie. The events that precede this blog are utterly tragic, but from such tragedy there is hope that we can all do better in the treatment of life threatening anaphylaxis. I urge you to read on and to follow the links to the AMAX4 website, to talk about it with colleagues and to share widely. We thank Ben and his family for sharing their story and the wisdom.

In Australia human physiology is no different from the rest of the world.  It comes from the tragic death of the child of one of our own critical care community – Dr Ben McKenzie’s and his 15 year old son Max.  Max died from hypoxic brain injury secondary to asthma precipitated by anaphylaxis.  He was initially GCS 15 with an SaO2 100% when he became symptomatic and he did everything right in getting help early.  Tragically he deteriorated and his heart stopped after a prolonged period of attempted airway support using BVM.  He finally achieved ROSC when an ETT (surgical airway/FONA) was performed. Max’s father (Ben) had to direct and then complete this by putting his own finger in Max’s neck to get the bougie to pass and then to intubate Max himself.  Max was only a difficult airway because of the laryngeal oedema that developed over the 40 minutes multiple specialists attempted BVM. For those of you familiar with Martin Bromley’s work you will no doubt already be drawing comparisons. Tragically Max did not survive, but Ben has taken the view that we can do better if we prepare for similar cases that are inevitable in our practice.

Ben presents the new AMAX4 algorithm through the website amax4.com and front loads it with the video “Just a routine Resuscitation” that includes a best practice simulation for an asthma/anaphylaxis arrest.  It is hard to argue with the approach and in my mind this story and the subsequent drive to make changes for the better now sits alongside ‘just a routine operation’ (the video made by Martin Bromley), in asking healthcare staff and systems to look at themselves and to do better through advocacy from those who have suffered unimaginable loss.

There are a couple of novel things that the AMAX4 algorithm does – firstly it articulates a hard stop and hard limit (hard deck if you watch the lecture) which is the time to hypoxic brain injury. This is novel but has parallels with safety mechanisms in other industries and is likely to be helpful in overcoming team inertia and setting an absolute standard that we can all train for and construct our systems around.  Errors during acts of omission are unusually tolerated in critical care compared to errors made during acts of commission and this goes some way to address this.

The second thing is that it shifts the pendulum regarding intubation in arrest situations back to a more sensible place in the hospital setting –  it implores critical care specialists to be “specialists” and not apply the same algorithm to all pathologies.  It also implores specialists to deliver the definitive airway care they are trained to do in a well resourced setting.  It identifies that any guideline regarding airway management needs to be explicit about which audience it is intended for.  If you are in the prehospital environment or if unfamiliar with advanced airway skills, then BVM or LMA may be appropriate (except in asthma/anaphylaxis and airway obstruction).  But anaesthetists, emergency physicians and intensivists cannot extrapolate that prehospital data to the hospital where they are supposed to be rapidly delivering definitive care in a well resourced setting.  There is limited validity in extrapolating prehospital studies to hospital – unless you are talking about clinicians unfamiliar with laryngoscopy/intubation, or on a deep dark ward or in the foyer of the hospital.  The same could be said in the UK for advanced prehospital critical care teams. Severe asthma/anaphylaxis is a group of patients where early advanced interventions may well make a difference, and anecdotally I’ve been involved in a few cases where I am confident that advanced airway care made a significant difference.

Ben argues that in hospital resuscitation teams every patient who needs an ETT should be able to get one “early” (including VF patients who don’t wake up after their second shock).   Similarly, in hospital teams (and in many prehospital teams) we manage ABC in trauma simultaneously – why are medical resuscitations any different? Delegating someone with expert airway skills to control the airway while other definitive care is occurring around them IS the standard of care in that environment.  So we need to be careful which guidelines specialists are using in that well resourced environment – some of us are better than others and don’t need guidelines here.  But under cognitive overload, sometimes we all need a helping hand and a prompt.

Caution should also be used in interpreting the prehospital studies about intubations LMA/BVM. Most studies show no difference at 30 days or 72 hours rather than making LMA or BVM superior.  There are subsets of patients and nuances regarding treatment failure which these studies aren’t powered to detect.  But there are some clues – for example – BVM vs ETT (Jabre et al) showed a higher ventilation failure rate and aspiration (!) and the PART study showed twice as many loss of airway events.  In which patients did this occur and what did it mean for those patients?  Can we better select patients for each group?

The principle issue that AMAX4 addresses is that in cardiac arrest from anaphylaxis/asthma/airway obstruction the use of BVM and/or LMA will almost always fail. It might take time to realise this, but it may well happen and there are two devastating cases presented at amax4.com as testament to that.

So Ben and Tamara McKenzie ask you to watch the lecture and just a routine resuscitation.  They ask you to help try to achieve a zero death rate or brain injury rate for any young person who arrives in your care and is as yet uninjured from asthma or anaphylaxis.

Please follow this link to AMAX4.com and learn more about how we can all manage anaphylaxis better. I have and I’ve learned a lot.

More resources and links below (from LITFL website). Both LITFL and DFTB are supporting the AMAX4 message.

Max McKenzie
Martin Bromiley

DFTB https://dontforgetthebubbles.com/a-routine-resuscitation/

LITFL https://litfl.com/amax4-algorithm/

A routine resuscitation
AMAX4 Algorithm

Cite this article as: Simon Carley, "Just a routine resuscitation. The AMAX4 algorithm for anaphylaxis/asthma. St Emlyn’s," in St.Emlyn's, June 13, 2023, https://www.stemlynsblog.org/just-a-routine-resuscitation-the-amax4-algorithm-for-anaphylaxis-asthma-st-emlyns/.

Thanks so much for following. Viva la #FOAMed

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