Death by intubation?

Airway management, in particular the use of endotracheal intubation by paramedics, is a hot topic in EM at the moment.  There have been a lot of studies published, most of which show that intubation is harmful or at the very least not helpful.  Most of these studies are not of very good quality and most are not really able to be generalised to practice in metropolitan Melbourne.

However now there is a large study out of Japan that shows fairly clearly that intubation in cardiac arrest leads to poor outcomes.  Uh oh.  This has been blogged about in a number of other places, so I am not going to go into great depth, merely share a little of what I think and how I have adjusted my practice in light of this an other studies.

This study is a retrospective registry review of cardiac arrests in Japan, using the Utstein template to standardise data collection.  There is a great deal of statistical jiggery-pokery that goes on to account for confounding factors other than airway placement and I won’t pretend to even begin to understand most of it.  Generally speaking, the more tests that are applied to a set of data, the more suspicious one should become of the results.  On the other hand, this is a big pool of data.  Really big, like nearly 650 000 patients big.  A relatively small proportion of arrests were intubated (6%) which seems unusual to someone who is used to seeing 100% of arrests intubated (I’m not saying it is unusual or wrong, merely that it is very different to what I am used to).  More were managed with supraglottic airway devices (37%) and the rest with simple bag-valve mask.

The use of any airway was significantly associated with worse neurological outcome at one month and intubation was worse than SGA.  Bugger.  I am not going to try to dissect this paper too much as I really lack the ability to do so.  What I will do is talk about what I do about airway management in the arrested patient and why.

So the main trouble with intubation killing people is: I don’t buy it.  As far as I am aware there is no Plastic Induced Brain Death Reflex that comes from having some plastic between some vocal folds.  So this leaves two things that are causing poor outcomes.  One is how the tube is inserted and the other is what we do ventilation-wise once the tube is inserted.  Any interruption in CPR is a Very Bad Thing, and all too often intubation causes such an interruption.  I have been guilty of this myself and it is very common to see paramedics become task focused on placing that tube at all costs.  Hyperventilation is also a Very Bad Thing as it reduces venous return, diminishing effectiveness of CPR and this is also very, very common.  We are getting better at not hyperventilating our live patients with quantitative EtCO2 to guide us, but this is a bit trickier with a dead person on our hands.

Intubation is probably not going away in Victoria any time soon.  We have a very high success rate at intubation (>97%) with no unrecognised oesophageal intubations (at least since capnography became mandatory)  We also are either cooling patients post arrest or running trials on cooling patients during arrest.  To do this we need the patient intubated as it allows us to administer the ultimate anti-shivering agent safely, which is necessary to effectively bring down temperatures.

Because we are continuing to place ETTs during arrest we need to make sure that we do all we can to optimise CPR when intubation occurs and take great care to avoid hyperventilation.
Having followed the intubation kills debate for a while I have modified my approach to intubation in the cardiac arrest patient as follows.

After setting myself up at the head of the patient with all my toys I don’t worry too much about intubation until I have everything else running smoothly: CPR being done well, compressors rotated every 2 minutes.  I make sure that we have good IV access or place an external jugular cannula (or IO) and ensure that we are set up to give the right drugs at the right time (for what they are worth)

Once all this is sorted I go in with the laryngoscope whilst CPR is underway.  Most of the time I am able to gain an acceptable view and pass a bougie or a tube whilst CPR is ongoing.  If I can get a view but not pass the tube I wait for the natural pause in proceedings whilst a rhythm check occurs and quickly pass the bougie/tube then.  In this fashion I make sure that passage of the ETT does not interrupt CPR.
If I am unable to get a view at all I will attempt to blindly place a bougie during one pause, then follow with railroading the tube either during CPR or at the next pause.  If this fails, I don’t worry too much about it and carry on with basic airway management or place an LMA (iGEL soon, yay!)

Post intubation (and placement of an gastric tube) I either ventilate myself or at least try to supervise ventilation very carefully.  This is probably the most difficult part of proceedings as it is quite hard for people to gauge how much volume they are administering with every squeeze.  A ventilator would be a lovely thing in these situations (well, in any ventilation situation, but that is probably the topic of another post)

None of this is earth shattering stuff.  It should be pretty simple and straight forward for any paramedic to adjust their approach to intubation in the cardiac arrest patient.  All it requires is a little mindfulness of what we are doing and why we are doing it.  Will it help?  No idea.  Our service touts worlds best survival rates from cardiac arrest, so maybe we are doing something right intubating arrests.  On the other hand, I have not seen raw data so have no idea how much cherry picking of the data goes on.  I also have no idea if my method of avoiding pauses in CPR is of any use, but it makes sense to me in light of the data we have available.

Any thoughts or comments?  Feel free to chip in.

Robbie

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8 Responses to Death by intubation?

  1. johnwood237 says:

    Good post – thanks. It’s not clear from the study when intubation took place during the resuscitation attempt. It maybe that intubation came during prolonged resuscitation and therefore would most likely be associated with poorer outcomes, or perhaps was undertaken in particularly difficult airways with similar results. Who knows? The harm/ efficacy of intubation is not proven. We really don’t know – the evidence does not exist. There are many questions over airway management / ventilation during resuscitation which require an answer but we are where we are. Most paramedics now understand the importance of minimally interrupted chest compressions and I see good practice everyday. I was a bit worried you said it was common to see paramedics getting focused on tube placement, this is not the case in my experience, in recent times. Practice varies, some will go with SGA – if it works then leave it. Some will go straight to intubation but if difficult then go to SGA. I have been in recent contact with some high performing USA systems who run a lot of arrests with BVM. This debate will run. In the UK there was a concerted move from non paramedic healthcare professions to remove intubation from paramedic practice almost overnight and with no consultation with the profession. This was strongly resisted and this resistance has been, on the most part successful. This did however did leave us in an entrenched position with the poles of the argument glowering at each other. I sense recently that there is a growing willingness for both sides to look at the argument and try to discover the truth about intubation during arrest, whoever performs it, and arrive at a consensus which will improve pt outcome. I really hope this is achieved. Now intubation post ROSC ……. another story ….

  2. Josh says:

    Was recently discussing this same study on twitter with colleagues. A few thoughts:

    Despite looking into the study, I’m not sure how well they adjusted for time to intubation/SGA placement. If they’re following best practice, that may be fairly well along in an arrest, and it’s possible early ROSC and associated good outcomes would be associated with BVM only ventilation. The authors note they adjusted for time intervals (and I may have missed something) but I don’t know if that means response time, down time, time to rosc, CPR intervals between rhythm analysis, all of the above, or something else entirely.

    My second thought is regarding hyperventilation: while ETCO2 is a great confirmatory tool for airway placement, I’m not sure we have data yet that lets us associate intra-arrest ETCO2 levels with the appropriate amount of ventilation, especially since it depends on so many factors like underlying metabolism, fluid load, and effective CPR. Though we’re targeting 6-8 ventilations per minute (in my system) with an advanced airway, that may still be causing too much intra-thoracic pressure, and decreasing circulation by enough over the course of each minute to affect the outcome. While we can quantify some things with ETCO2, maybe we need manometers to measure airway pressure. (Then there’s the whole ITD debate, too.)

    Lastly, if you go back to the last major Japanese prehospital study on epinephrine, they had described a system going through some major changes in recent years – from BLS only (no defib!) providers, to MDs attending arrests in urban areas, to a limited airway, epi, defib ALS skillset for some providers. I don’t know that this is comparable to systems elsewhere, and I don’t know if it’s fair to judge advanced airway vs BVM cohorts when there are so many other factors changing in the Japanese system at the same time.

  3. ambofoam says:

    Thanks for the replies. You both raise the same, very valid point in that there may be survivor bias in this data with early ROSC resulting in no intubation.

    It is also very hard to generalise the results from this trial to the practice or experience of other services. Indeed this is a problem with almost all of the airway research that is floating around. Much of it seems to come from services that are perhaps not performing as highly as they could, or it is not making fair comparisons of the situations in which intubation is occurring (Wang’s head injury study out of ?Philly springs to mind)

    John, I did word my post poorly: I should have said that I used to see a lot of interruption in CPR to place tubes. This doesn’t occur anywhere near as much these days except sometimes when there is a new paramedic coming to terms with the new toys. Nonetheless it is easy to succumb to the ‘hold on a second’ reflex if one is having trouble passing a tube.

    Josh, the issue of how we measure ventilation in arrest is indeed a tricky one. I am aware of some US services that do not ventilate at all during arrest, using passive oxygenation via a non-rebreather mask instead. I do not know their results. When one considers the low flow state that arrest patients are in, maybe this is entirely adequate? It would also avoid the issue of inflating the stomach with air and increasing pressure on the diaphragm through poor BVM technique.
    Of course we then again strike the question of whether we still need to intubate at all if this approach is adequate.

    I think it is disappointing to hear of services ditching intubation outright based on the rather poor evidence that is available currently. It may be that intubation in the field causes more harm than good, but that question has not been answered yet and it seems a little premature to abandon it altogether at this stage. We should be using these studies as starting points for some more rigorous research before we throw the baby out with the bathwater.

  4. johnwood237 says:

    @ParamedicABC is hosting a debate on Cardiac Arrest this Sunday (3rd) at 2000 hrs GMT on twitter if you are interested. It’s a new venture, would be great if you could chip in !

  5. ambofoam says:

    Thanks, I’ll try to drag myself out of bed in time to take part, it sounds interesting.

  6. Tingles says:

    Great discussion. My thoughts on this mirror the previous comments i.e. it is hard to know how much selection bias played a part in their outcomes. Additionally, it is hard to draw conclusions from a heterogeneous cohort caused by system changes over a long period of time – one of the limitations of large cohorts gathered over a long time.

    Interestingly, their is now some literature (albeit studying outcomes in pigs) which suggest that SGAs may reduce carotid blood flow in cardiac arrest (I cant remember the reference but I think EMCrit had a podcast on it). We also know that compression only with O2 via facemask (add SGA too) may work, it is somewhat risky in the bloke who arrests following ingestion of a pizza and sixpack of beer!

    So, where does that leave us? My practice is to persist with whatever airway (or lack of) is in place when I arrive IF it is working effectively and I do not consider the patient high risk (based on the science of gestalt). If the resus is unsuccessful, so be it. If we achieve ROSC, then I will consider the need for intubation for control of ventilation, cooling and / or safe transport.

    Regarding EtCO2, it is of limited benefit in controlling hyperventilation in cardiac arrest, other than to show if dynamic hyperinflation (“breath stacking”) is occurring. It is probably a useful predictor of outcome, and will be the first indication of ROSC, but for both of these it will work equally well attached to a BVM or SGA as to an ETT.

    My take on this topic – ETT is still a valid and useful tool in cardiac arrest if applied wisely by well trained professionals not just intent on “sinkin’ the tube”.

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