We know it’s been a sore subject for some as many feel it's a direct insult or attack on paramedics. At MedicineWithout, we hope some more knowledge might provide clarity on the situation. Here, we take a look at one of the key clinical trials that influenced a lot of these protocol changes.
Here’s the paper:
Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018;320(8):769–778. doi:10.1001/jama.2018.7044
What question was the study trying to answer?
The study was trying to determine whether a strategy of initial supraglottic airway placement (laryngeal tube such as the King airway in this case) or initial endotracheal intubation by EMS was more effective in prehospital cardiac arrest.
What were the outcomes?
The primary outcome was 72-hour survival. Secondary outcomes included return of spontaneous circulation, survival to hospital discharge, and favorable neurologic status at time of hospital discharge defined as Modified Rankin Score less than or equal to 3. If you are not familiar with the Rankin score, Check out this link https://www.mdcalc.com/modified-rankin-scale-neurologic-disability.
Other secondary outcomes were EMS airway management course and hospital adverse events.
What was the study design?
This was a multicenter cluster crossover randomized clinical trial using multiple EMS agencies from the Resuscitation Outcomes Consortium.
27 EMS agencies were randomised in 13 clusters to an initial airway strategy of laryngeal tube (N=1505 patients) vs endotracheal tube (n=1499 patients).There was then crossover to the alternate airway strategy at 3 or 5 months. Cross overs between the groups could occur more than once. Study duration was from 12/1/2015 to 11/10/2017.
Who was in the study?
There were a total of 3004 enrolled patients. The patients were age 18 or older who suffered a non-traumatic out-of-hospital cardiac arrest requiring ventilatory support or advanced airway management.
What were the key results?
These are the results with significant differences:
Primary outcome:
Seventy-two hour survival was 18.3% in the LT group vs 15.4% in the ETI group (adjusted difference, 2.9% [95% CI, 0.2%-5.6%]; P = .04).
Secondary outcomes:
Results are given in the format of laryngeal tube % vs endotracheal intubation %
1. return of spontaneous circulation (27.9% vs 24.3%; adjusted difference, 3.6% [95% CI, 0.3%-6.8%]; P = .03);
2.hospital survival (10.8% vs 8.1%; adjusted difference, 2.7% [95% CI, 0.6%-4.8%]; P = .01); a
3. favorable neurological status at discharge (7.1% vs 5.0%; adjusted difference, 2.1% [95% CI, 0.3%-3.8%]; P = .02)
All in all, laryngeal tubes performed better!
Also of note:
The initial success rate for laryngeal tube insertion was was 90.3%.
However, for endotracheal intubation, first pass success was only 51.6%
Overall success rates for laryngeal tube insertion and endotracheal intubation including rescue attempts were 94.2% and 91.5%, respectively.
What were the limitations?
The study did not really look at effect of airway choice on chest compressions (quality or continuity of chest compressions) which may have affected out of hospital cardiac arrest outcomes.
The study also only used the laryngeal tube (King type) supraglottic airway and so cannot comment on other supraglottic devices such as LMAs or Igels which are commonly used.
Also, the first pass success rate for endotracheal intubation was only 51.6% It’s possible that a better first pass success rate would have affected the outcome. It’s a little bit unclear as to why the success rate in this study was so low as it has been previously been reported to be about 86.3% for non-RSI/non-drug facilitated endotracheal intubations2. However, it is hard to argue with as 27 different EMS agencies were involved.
What was the study conclusion?
Among adults with out of hospital cardiac arrest, a strategy of initial laryngeal tube placement compared to endotracheal intubation produced a small but significant improvement in survival at 72 hours.
Dr. Bar’s Commentary
I think that study forces us to take a hard look at endotracheal intubation by EMS. A first pass success rate of 51.6% among EMS providers from 27 different agencies is dismal. I also don’t think it should be taken as an insult to any individual paramedic. At first, reading numbers like that can come across as shocking, but if you think about it, it's not that surprising. EMS providers have to intubate under the worst conditions possible, but learn to intubate under the best possible conditions. Think about how we all learn to intubate. We learn by intubating manikins on a table and then go to the operating room with a perfectly prepped, NPO patient with all the advanced airway equipment under the sun, and all the time in the world. Then come back to the reality of EMS. I don’t know about you guys, but I’ve never seen a patient who needed intubation in the field, lying in a perfect position on their kitchen table. Instead you have to intubate them on the floor, in the bathroom, often with vomit already coming out of their mouth. It’s no wonder, first pass success is much worse in EMS providers. Also, let’s be real with ourselves, ladies and gents, how many live tubes are each of you doing in the field each year? I would wager a guess that many of you could count them on one hand depending on where you practice.
So...if you take it all together, you have a group of dedicated, hard working professionals that you had intubate a manikin a couple of times on a table or in the OR under perfect conditions in medic school and then throw them into the field and expect them to be able to intubate perfectly. We have set up our EMS providers to fail in this regard. And we have to ask ourselves, is it right for the patient? The patient doesn’t necessarily need to be intubated right away. They need their airway managed. And they need it managed in the simplest, most effective way possible. And if that means dropping a King tube in the field, then that’s what we should be doing.
Now, don’t misunderstand, there are situations where paramedics still need to intubate. Try putting an LMA in a patient with angioedema or anaphylaxis. Good luck getting past the tongue. Only an ET tube is gonna suffice in these Hellish airways. Also, sometimes, that supraglottic airway just isn’t doing what it needs to be doing, namely oxygenating and ventilating the patient. If it isn’t oxygenating or ventilating, then you need that ET tube. Not to mention, those in rural areas who may need to work with this airway for quite a while are gonna need an ET tube.
So...what can we do about all this?
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Be humble. If you are a medic reading this, remember it’s about managing the patient’s airway. Managing the airway does not equal endotracheal intubation everytime. It means oxygenating and ventilating the patient. Do what you need to get that done and more often than not, a supraglottic device will get that job done and do it faster letting you focus on other critical aspects of care.
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We need to train our medics better and under the conditions that more closely mimic the conditions that they will operate under. This means putting that manikin on the floor, in a car, in a bathroom, upside down. Better training gives better results. Better yet, sign your medics up for a cadaver based airway course. One example is Rich Levitan’s course in Baltimore, which is spectacular. Also, it may be worth it to get medics in the ER with us to practice some more “emergent” type airways. It’s still not the same as the field but it's better than the OR.
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Get videolaryngoscopy in the field. It is an absolute must when you are trying to intubate under the worst of circumstances.
Reference:
1.Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018;320(8):769–778. doi:10.1001/jama.2018.704
2.Hubble MW, Brown L, Wilfong DA, Hertelendy A, Benner RW, Richards ME. A meta-analysis of prehospital airway control techniques part I: orotracheal and nasotracheal intubation success rates. Prehosp Emerg Care. 2010;14(3):377-401.
***UPDATE*** 3/14/2022
The National Association of EMS Physicians (NAEMSP) recently put out a position statement on airway management commenting on this very topic. We'll be sure to cover it in a future post. Stay tuned!