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Thursday, September 22, 2011

Use of the Straight ("Miller") blade

A lot of people are talking about the future of endotracheal intubation for EMS, about when it should be done, allowed, or even if it should be taught. This is NOT one of those discussions.
Also not a discussion of the utter nonsense shown in this picture.
If you are going to intubate, however, you should know how to do it. And it shouldn't be just one way to do it, but more like 2 or 3. 

On the other hand, I started with the Mac #3 as a new medic, but quickly became a "The-#4-Mac-has-never-let-me-down" kinda guy. Still am, even as an ER doc.

Candid confession - I have no talent for the Miller
I'll be honest though. One of the chief reasons I'm a "#4 Mac guy" is that I never learned to use the Miller effectively. 

Sure, people say that "It's better for peds," or "It's better for trauma intubations." But I've had trouble sweeping the tongue with the tiny flange when I used it like a Mac, placing it on the right side, and trying to move the tongue to the left. 

Placing it in the midline was even worse; I had no control of the oropharynx, and the tongue would just flop around. And it didn't even make sense to me - if moving the tongue with a curved blade didn't give me the view I needed, why would smooshing the tongue help?
A completely mythical view of the cords.
Turns out that my instincts were not far off the mark! A number of anesthesiologists have come up with a better techniques for use of the straight blade for difficult intubations, avoiding any tongue-control issues, as well as providing clearer views of the cords.

Paraglossal approach with the Miller
There are some variations, but they all start with proper positioning of the head and neck, either in "sniffing position," as with your medical patients, or in neutral, in-line stabilization for your trauma patients. 

Much like a Mac, you place the blade into the corner of the mouth, and advance it along the groove between the tongue and the tonsil ("paraglossal"). Then, however, things go a little differently.

Levitan, on his excellent AirwayCam website, describes the paraglossal approach:
"Proper position is achieved with straight blades by deliberately directing the blade to the right paraglossal space. No tongue should be present to the right of the blade.  Full insertion of the blade should occur through the right lateral mouth, over the molar dentition, and while the distal blade may then be directed medially, the proximal blade should never be brought back towards the midline, otherwise it will hit the central incisors.

After the epiglottis edge is identified, the handle must be tilted forward (e.g., the tip moves backward, toward the posterior hypopharynx). The blade is then inserted slightly farther (~1-2 cm), and the tip passed under the epiglottis.  Once the epiglottis is “trapped” under the blade tip, the blade is rocked slightly backward (handle brought slightly more upright) and then the lifting force increased."
Note that the blade is to the right of the nose, and that the ET tube runs under (not through) the blade lumen.
"Tube delivery should be done using the extreme right corner of the mouth, and come up from below the line of site.  An adult tube will not fit through the lumen of a Miller blade (and should not be attempted)."
Here's a drawing of the technique, from a key article by Henderson:
Blade stays on the right side of the nose.
Look at that finger hooked into the corner of the mouth - that's a real helpful technique in normal intubations, and it's key here. You are not moving the blade to the left, so you need some help on the right to insert and manipulate the ET tube. (Great article - contact me by Twitter or the Facebook page if you want a copy.)

Does it work?
A study from 2010 in China confirmed the benefits of this technique. The title says it all: Prevention of dental damage and improvement of difficult intubation using a paraglossal technique with a straight Miller blade. Of course, we don't care that much about teeth when TSHTF, but it's a nice touch.


Another study (download here), done in 2008 in Canada, also showed that you could get a better view with this technique than with  the standard curved-blade approach. There is also a great discussion about the history of laryngoscopes, and how we ended up with the current designs.


Better view - but more difficult to place the tube? 
One trade-off of this better view may be that it is harder to actually place the tube. 

In the 2003 paper "Straight blades improve visualization of the larynx while curved blades increase ease of intubation," Spanish anesthesiologists noted that use of a Macintosh blade, while providing an inferior view of glottis, nonetheless made it easier to place the tube. (Download

Of course, if you don't have gottic view in the first place, it's going to be hard to place the tune


The Bottom Line

So, while the future of EMS ET intubation is a matter of much discussion, the need to be proficient in various techniques is not. Anybody who checks a set of blades at the start of a shift should know a number of techniques for using them. Hope this helps!

2013 update
 

3 comments:

  1. I've used a Miller #4 for most of my adult intubations for over 20 years. I've never seen the technique you describe, but I'm going to try it out the next time I intubate.

    Thanks and remember, "There is no one who can't be intubated with a #4 Miller and a strong forearm". ;)

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  2. I've used the Miller on an actual patient a whopping one time after it was handed to me by the anesthesiologist without another option. Having read Dr. Levitan's book and practiced with the technique on mannequins beforehand, I attempted the paraglossal approach you describe and failed miserably. I still couldn't get adequate tongue or epiglottis control and just ended up inflicting a bit of soft tissue damage before cutting my losses and bailing.

    The folks I've worked with who use the Miller love it, but I'll stick to the #4 Mac. For me, there's a certain comfort that comes from being able to walk my way straight down to the epiglottis with a mid-line Mac approach if all else fails. Unfortunately it's hard enough to get enough experience to become proficient with one approach, let alone both.

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    Replies
    1. Vince D-
      I'm a mac #4 devotee myself, and find it hard to force myself to practice other approaches. Good for you for making (being forced to?) make the effort!

      When people say the only use the Miller, I look at them like how I look at people who say they never drink coffee, or never watch TV. Like - Good for you, but really?

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