The last paper we were working on for the EMS Research Podcast was this paper on the use of a bougie in the intubation of a simulated patient with spinal immobilization.
Is BAI (Bougie-Assisted Intubation) an improvement over traditional intubation (ETI or EndoTracheal Intubation)?
For this study, we had three separate hypotheses: The first was that BAI would be more successful than ETI in a difficult airway scenario; the second was that BAI would take no more time to complete than ETI in a difficult airway scenario; and the third was that BAI would be perceived by providers to be as easy to perform as traditional intubation.[1]
1. Better.
2. As fast.
3. As east to use.
That is a lot.
The study was done inconjunction with an annual skills competency assessment session. Each participant was being assessed for competence in nine different out-of-hospital procedural skills, and the study involved only one of the skill stations. The participants gave written consent to participate, but they were blinded to which skill was being assessed and what data were being obtained during the study. At the ETI station, a brief explanation and demonstration of BAI was given to each participant.[1]
An intubation mannequin had its neck strapped down to simulate motion restriction that would be consistent from intubation attempt to intubation attempt.
Before and during the study, three experienced emergency physicians verified that the best obtainable view by direct laryngoscopy was a partial glottis opening of approximately 20%—equivalent to a grade III Cormack and Lehane glottic view.[1]
Image credit.[2]
Grade III is a lovely view of the epiglottis, but that is as good as it gets with Grade III. A good view of the airway is going to involve a glimpse of arytenoid. More than that is just gratuitous. As with the rest of medicine, our goal is not to do as much as possible, regardless of the harm. Our goal is to do as little as possible, realizing that doing more often means doing more harm.
Since Cormack-Lehane Grade III means that the glottis is not visible, is it appropriate to call this a Grade III glottic view?
The participants were not aware that they were being timed. Timing began when the laryngoscope blade entered the mouth and ended with ventilation through the ETT with the BVM (evidence of successful ventilation as determined by manikin lung inflation or evidence of failed placement as determined by manikin stomach inflation).[1]
I do have problems with both of these.
Timing should begin when the last ventilation is delivered, rather than when the blade enters the mouth. The patient does not care why there is a delay in oxygen delivery, only that there is a delay in oxygen delivery. If we want to use hypoxia as a guide, then hypoxia also has nothing to do with when the blade enters the mouth.
The timing should end with successful ventilation either through a properly placed tube or through the BVM after recognizing incorrect placement. They did not record times for incorrectly placed tubes, but this information is relevant when dealing with real patients.
Also, is placement as easy to identify as with Fred The Head, where the lungs are visible? A requirement for a good assessment should be a part of the study. From the end of the paper, the reference to this method being similar to what could be done with the SimMan, suggests that this is Fred, or a close relative of Fred.
We found this model to be an easy and inexpensive way to provide EMS personnel with a difficult airway experience without the use of a high-fidelity simulator,[1]
This is not a criticism of Fred the Head or SimMan. We need to pay attention to what they are there for. They are there to assist us in creating a simulation of a real world environment, not to assist us in creating scenarios that are easy to measure. Their utility is that we can do both, when we address the reality of the simulation first. Otherwise, we begin to teach bad techniques.[3]
We can use low fidelity equipment to teach people to do the right thing, but we can also use high fidelity equipment to teach people to do the wrong thing. We need to understand what we are teaching.
Should we be teaching that time is not important if we do not place the tube between the cords?
Upon completion of the two techniques, each participant was asked to complete a five-point Likert-style survey to assess his or her overall ease of intubation with both techniques in this particular difficult airway model.[1]
How did the bougie do?
41% rated the ease of intubation the same for the two methods (asterisked values in Table 2), 50% rated the BAI to be easier than traditional ETI, and 9% rated traditional ETI to be easier than BAI. The participants perceived the BAI to be easier than traditional ETI in this difficult airway model (Jonckheere-Terpstra exact p = 0.0006).[1]
It is interesting that for a supposedly very difficult intubation, 16/35 participants (just under half) rate this simulated difficult airway as easy or as very easy.
There are many possible explanations, arrogance, excellence, not really very difficult, great airway education, et cetera.
3. As east to use?
Yes.
There was no significant difference in the average time to successful intubation (20.4 seconds for BAI [standard deviation (SD) = 9.1 seconds] versus 16.7 seconds for ETI [SD = 9.6 seconds], paired t-test p = 0.102). When controlling for order of techniques attempted, the difference between the groups remained nonsignificant (p = 0.0901). The analysis was limited to the 27 participants who were successful with both methods.[1]
This is one of the reasons that airway management should be seen as more complicated than just in the hole/not in the hole. The subjects who were least successful had their times eliminated from this comparison of times.
Does that bias the results?
I do not see how it can be considered as anything other than introducing a bias to the results.
Time from last ventilation to first ventilation is the time that matters. Whether the ventilation is through an endotracheal tube or a BVM is not as important as the ventilations.
If the tube is placed incorrectly, the amount of time until this is recognized does matter to the patient. This is one of the reasons why we should always listen over the stomach first.[4],[5]
2. As fast?
They did not come up with a statistically significant difference in times, but they only compared times when the subject was successful with both methods. Since almost all of the failures were when the bougie was not used, this would seem to preferentially eliminate the worst times for the traditional intubation.
The trend was toward a difference in favor of traditional intubation, but the method of time keeping had what appears to be a strong bias built in toward whichever method had the most failures.
The most failures turned out to be with the traditional intubation.
2. As fast?
There was no statistically significant difference in what was measured, but what was measured is not what should have been measured.
Maybe faster. Maybe as fast. Maybe slower. We do not know.
There was significantly greater success in intubating the simulated difficult airway with BAI than with ETI (94% vs. 77%, McNemar’s exact p = 0.0313). The order of techniques attempted did not influence this conclusion.[1]
94% success vs. 74% success.
If we are to continue using intubation, maybe we should use bougies all of the time.
1. Better?
Much better.
The problem with the bougie is that it is too long to be carried by EMS without bending it. Management tends not to approve of bending equipment that is not supposed to be bent. At 2 feet long, or longer, my excuse has been that the bougie is impractical in my gear.
This is the pocket bougie by Bomimed.
That will easily fit in my airway bag, or even a cargo pocket.
I have run out of excuses for not having a bougie with me.
I do not have any financial connections with anyone manufacturing or selling bougies. I just like the way this makes it much more practical for those of us in EMS to improve our intubation first pass success rates.
Dr. Scott Weingart (EMCrit) and Dr. Minh Le Cong (PHARM) have both covered the Pocket Bougie.
Notice that when you use a bougie, you keep the laryngoscope in place until the tube is placed. Holding the bougie with the same hand that is holding the laryngoscope makes this an easy one person procedure.
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Footnotes:
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[1] Comparison of bougie-assisted intubation with traditional endotracheal intubation in a simulated difficult airway.
Messa MJ, Kupas DF, Dunham DL.
Prehosp Emerg Care. 2011 Jan-Mar;15(1):30-3. doi: 10.3109/10903127.2010.519821. Epub 2010 Nov 10.
PMID: 21067319 [PubMed – indexed for MEDLINE]
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[2] Rapid airway access
Sérgio L. AmantéaI; Jefferson P. PivaII; Malba Inajá RodriguesIII; Francisco BrunoIV; Pedro Celiny R. GarciaV
Print version ISSN 0021-7557
J. Pediatr. (Rio J.) vol.79 suppl.2 Porto Alegre Nov. 2003
doi: 10.1590/S0021-75572003000800002
Free Full Text Article from Jornal de Pediatria.
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[3] On Combat
by Lt. Col Dave Grossman (with Loren Christensen)
Chapter Two
Whatever is drilled in during training comes out the other end in combat–no more, no less
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[4] Intubation Confirmation
Fri, 25 Apr 2008
Rogue Medic
Article
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[5] More Intubation Confirmation
Sun, 27 Apr 2008
Rogue Medic
Article
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Messa, M., Kupas, D., & Dunham, D. (2011). Comparison of Bougie-Assisted Intubation with Traditional Endotracheal Intubation in a Simulated Difficult Airway Prehospital Emergency Care, 15 (1), 30-33 DOI: 10.3109/10903127.2010.519821
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I carry a Pocket Bougie myself.
And with that, you’ve given me an idea for my next EMS1 Clinical Tip.
Thanks!
Ambulance Driver,
It might be difficult to intubate while tunbling down a flight of stairs without one. 😉
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It is one of those things that seems obvious after you see it, but I had never done more than try to make an ordinary bougie fit into my gear – and failed to have a bougie that was good for anything practical afterward.
The place to carry an ordinary bougie is on the stretcher, but that only works if you have the stretcher at the patient’s side when it is time to intubate. For some odd reason, patients do not plan things out that way.
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