Incidence and Predictors of both DL and DMV

Carlos Danger

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Lots of studies look at predictors of difficult laryngoscopy and difficult mask ventilation separately. What we know from that research as that clinical predictors of difficult airway management are quite unreliable and highly operator-dependent.

This is the first study I've seen that examines and correlate predictors of both difficult mask ventilation and difficult laryngoscopy, using a large sample size and across 4 academic medical centers.

At the end of the day I don't know whether this study really tells us anything we didn't already know, but if nothing else it confirms other related research and is an interesting read.

Incidence, Predictors, and Outcome of Difficult Mask Ventilation Combined with Difficult Laryngoscopy: A Report from the Multicenter Perioperative Outcomes Group. Anesthesiology. 2013 Sep 25.

BACKGROUND::
Research regarding difficult mask ventilation (DMV) combined with difficult laryngoscopy (DL) is extremely limited even though each technique serves as a rescue for one another.

METHODS::
Four tertiary care centers participating in the Multicenter Perioperative Outcomes Group used a consistent structured patient history and airway examination and airway outcome definition. DMV was defined as grade 3 or 4 mask ventilation, and DL was defined as grade 3 or 4 laryngoscopic view or four or more intubation attempts. The primary outcome was DMV combined with DL. Patients with the primary outcome were compared to those without the primary outcome to identify predictors of DMV combined with DL using a non-parsimonious logistic regression.

RESULTS::
Of 492,239 cases performed at four institutions among adult patients, 176,679 included a documented face mask ventilation and laryngoscopy attempt. Six hundred ninety-eight patients experienced the primary outcome, an overall incidence of 0.40%. One patient required an emergent cricothyrotomy, 177 were intubated using direct laryngoscopy, 284 using direct laryngoscopy with bougie introducer, 163 using videolaryngoscopy, and 73 using other techniques. Independent predictors of the primary outcome included age 46 yr or more, body mass index 30 or more, male sex, Mallampati III or IV, neck mass or radiation, limited thyromental distance, sleep apnea, presence of teeth, beard, thick neck, limited cervical spine mobility, and limited jaw protrusion (c-statistic 0.84 [95% CI, 0.82-0.87]).

CONCLUSION::
DMV combined with DL is an infrequent but not rare phenomenon. Most patients can be managed with the use of direct or videolaryngoscopy. An easy to use unweighted risk scale has robust discriminating capacity.
 

Christopher

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I enjoyed this paper when I saw its article in press. Fit nicely with NAP4 and some of the other larger DA papers.

My big takeaway from all of the difficult airway research is that for field providers we're really not great at predicting it and we are not given a means to overcome it. We have tools A, B, C, and D...but no strategy besides "put plastic in glottis, or put plastic above glottis."

(Theoretically, the anesthesia folks have a strategy for when they encounter a difficult airway; although when I asked what our plans were during my last rotation thru the OR, it was basically, "you need to put plastic in the glottis".)

What I'd really like to see is incorporating the findings from papers on unanticipated difficult airways and the strategies employed to salvage or achieve proper ventilation with DA strategies into a simple plan for every airway. I'm trying to work Dr. Chrimes' Vortex into my own service, but it is really hard getting checklists and plans to be the norm for airway management (we accept it without question in other areas...so bizarre).
 
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Carlos Danger

Carlos Danger

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I had a difficult time understanding the Vortex approach when I first read about it, but I went over it again a few days ago and it started to make a lot more sense to me. It seems like a really good way to conceptualize a rational approach to airway management.

I think checklists are certainly helpful but I can also see the practical challenges with implementing them pre-hospital. I think the best way is probably to keep the list as short as possible and simple, preferably using a mnemonic as a memory aid, and having the airway protocol require the checklist to be recited from memory by one provider and verbally confirmed by another in a challenge:response format, prior to sedation & paralysis.

Theoretically, the anesthesia folks have a strategy for when they encounter a difficult airway; although when I asked what our plans were during my last rotation thru the OR, it was basically, "you need to put plastic in the glottis".

Yeah, airway management really it isn't quite as different in the OR as some ED bloggers like to claim. There are obvious advantages and special tools available in the OR, but most of them rely on pre-identification of the difficult airway, and are little help once you've missed a couple of attempts and the sat is starting to drop. At that point the options are pretty much the same whether you are in the OR, the ED, or pre-hospital: mask ventilate, try a different device, or cut the neck.

In my mind the biggest factor in patient safety when it comes to airway management is whether you can mask ventilate, because, as I had drilled into my head in my anesthesia training but didn't have stressed nearly enough in my paramedic training, "if you can mask effectively, you DO NOT have an airway emergency." Even though that isn't really the point of this study, that's what I most take away from it.
 

DiverMedic

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Alternative Airway Devices

I recently did a literature review for Alternative Airways for Failed Endotracheal Intubations in Cardiac Arrest. There is a lot of information that I sifted through and two names popped up multiple times: Dr. Henry Wang and Dr. Kurt Ruetzler. I attached two of their articles here. I think this might be what you are looking for Christopher. Enjoy!
 

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