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.