Intubating using MAC blade

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foodie83

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I am hoping for some feedback from folks- I'm a new CA2 and certainly my direct laryngoscopy skills have improved immensely over the past year. However, I still have one problem that's driving me nuts... when using a MAC blade, I am almost always super close to the patient's teeth. I've been asking attendings for weeks now about feedback re: my technique, what i might be doing wrong, etc. No one has told me that I'm doing anything drastically wrong, need to change things up, etc.

It's driving me nuts, because I'm not sure that other folks have this issue. I had one attending who told me he is also usually close to the teeth with a MAC, and doesn't worry once you are keeping the blade static and not moving it and of course not pulling it backwards.

I don't know if my problem is that i'm not using enough forward/upward "force" on the handle? Not keeping enough neck extension? I find that I get a perfect view when I DL and have my right hand under the head to get a little extra extension, but as soon as I take my right hand out to grab the tube the back of the blade falls closer to the teeth...

Any advice, or thoughts from someone else who has had this issue? I really want to fix it but I don't know what I should be doing differently... thanks!
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It's hard to know without actually seeing what you're doing. If you're losing your view when you remove your right hand consistently, you might be over-emphasizing extension and might just need to work on positioning better into sniffing position.

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How far from the teeth do you want to be?
A MAC blade is thicker than a miller and as a result you have less space left in the mouth, so being close to the teeth is OK, breaking the teeth is not!
 
MAC blades can be close to teeth. We use reduced flange MAC blades. I think it has reduced our incidence of dental trauma.
 
Like was said above, positioning can make a huge difference. At the head of the bed you might not be able to see it. If you ever have the opportunity to the be supporting or teaching person from the side, you can really see a difference.

It is a good idea to focus on honing individual techniques once in a while. I remember as a rock star CA-3 on my 6th month of pediatrics that I was struggling to see the vocal cords on a kid. I wanted my attending to know that it was the kid's anatomy, not my lack of skills, so I asked him to intubate. He made a quick adjustment to the kids positioning and placed the ETT faster than I could blink. He said it was a great view. Humbled, I had to remind myself to not get casual with the basics.

Teaching is a great way to hone the basics. Sadly, doctors are notoriously bad teachers, which may be one reason you aren't getting proper feedback.

If you don't have a chance to teach, just rotate through the basics once in a while. From how to draw up syringes of drugs, to machine checks, to taping the eyes. Eventually the right techniques will happen more and more often. But don't expect to be an expert at the end of residency. Training continues for years.
 
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Often the problem is that the tip of the blade isn't inserted far enough under the vallecula. Just advance a little farther and use it as a lever. I've seen this error too numerous times to count when I'm teaching intubation. I rarely worry too much about position of the head into sniffing and I even more rarely miss getting a tube in on the first pass (maybe once a year). This includes "rescuing" people who can't intubate someone. Haven't knocked out any teeth either.
 
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I don't know man, with a curved blade positioning makes all the difference in my experience.

When I teach junior residents I even show them the difference between half-assed and proper sniffing by letting them DL with first poor and then good positioning on the same patient.

Sometimes you can see cords easily with poor positioning but most of the time it makes or breaks your view
 
If you want to jack the patient up with all manner of pillows and devices that you're going to have to subsequently remove before the case starts, far be it from me to tell you otherwise. I'm just relaying my experience. I've intubated thousands of patients at this point in my career using all manner of different towels, sniff pillows, table positions, etc. In truly difficult airways I haven't found that it makes a big difference. It's going to be difficult no matter what you do. The best bet is to recognize this in advance and plan accordingly.

A quicker trick though is to put the table in "back up" position and crank the head rest down one notch. This saves you from towels, pillows, etc. But if I think it's going to be tricky at all, I just start with the GlideScope or McGrath or whatever other indirect laryngoscope I have handy. I'm not a cowboy or a hero. I still think a lot of time is wasted with ridiculous and unnecessary positioning. My experience is unsuccessful laryngoscopy is often bad initial (or repeated) technique. Usually this is verified by my going in after someone's failed and getting it. Usually on my first look. I also recognize that not everyone is Lebron James or Tiger Woods when it comes to DL. No one should assume that individual skills are equivalent.

Bottom line is do what works for you. But don't hold up the case.
 
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I think the emphasis here needs to be that for the person who is learning to intubate, sniffing position will result in the least struggle for the learner. I had an attending in residency who told me that one of the aims of the program was to get each resident to ~1000 intubations, as quickly as possible. As simple as it may be, I think that there is a lot of wisdom in that. The sooner one achieves mastery, the sooner they gain understanding of what is superfluous and what is not. That is when the 'fat can be cut' so to speak. Learners need every aid they can to grow in confidence though. It's the training wheel method.

Otherwise, I agree with you, BuzzPhreed. If a patient is retrognathic and has buck teeth with a small aperture, perfect positioning isn't going to do you a lick of good. I still ramp in cases of extreme obesity, just to give room to work with...not necessarily because I think that the actual view will be poor.
 
Ca-2 here too.

I am mostly a mac daddy. The site I was just at for 4 months had Mac 3.5. I used that on EVERYONE. Good tool.

I use Miller for specific situations though.

Regarding Mac here are a few things I have found:

Sometimes you are TOO DEEP (some of us have that problem more often ;)) and the epiglottis flips down in front of you

With the Mac I use I direct my force more in a forward direction whereas with the Miller I lift more at a 45 angle. For the Mac I feel this helps to engage the valeculla and it directs the force away from the teeth.
 
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Mac 4 - the line of site from the end of the blade to the tip of the blade is greatly obscured by the great curve of the blade. The amount of tissue needed to be displaced in order to get the viewing axis is very large. it is a poorly designed blade.
 
Vaporized said:
Sometimes you are TOO DEEP (some of us have that problem more often ;)) and the epiglottis flips down in front of you
Click to expand...

That is one of the biggest problems with people who are just learning DL. Sometimes pulling the blade back a few millimeters will give you a much better view.
 
epidural man said:
Mac 4 - the line of site from the end of the blade to the tip of the blade is greatly obscured by the great curve of the blade. The amount of tissue needed to be displaced in order to get the viewing axis is very large. it is a poorly designed blade.
Click to expand...
Wow!
 
epidural man said:
Mac 4 - the line of site from the end of the blade to the tip of the blade is greatly obscured by the great curve of the blade. The amount of tissue needed to be displaced in order to get the viewing axis is very large. it is a poorly designed blade.
Click to expand...

The MAC 3 has more of a curve, compare the two. If the curve of the MAC 4 is truly an issue, the problem with the MAC 3 would be exponentially greater. That being said, I generally prefer the greater curve of the MAC 3, and use it more frequently. I always use the MAC 4 for adult blacks, and anybody who seems like they would have a deep larynx.
 
If man was meant to intubate with a straight blade, why are tubes curved? I rest my case.

/Mac 3 for women, Mac 4 for men, Miller 2 for kids. Keep it simple.
 
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I intubated a guy yesterday who had a big ole floppy epiglottis. I used a Mac 3. Couldn't see his cords. Couldn't get into position. Had a prior neck fusion to boot. What did I do? Just took the tip of that Mac 3 and slid it under the epiglottis and picked it up. Voila! Grade 1 view.

Why anyone uses a Miller blade ever is beyond me. Not that I can't intubate with a Miller blade just like any other airway ninja out there.
 
BuzzPhreed said:
I intubated a guy yesterday who had a big ole floppy epiglottis. I used a Mac 3. Couldn't see his cords. Couldn't get into position. Had a prior neck fusion to boot. What did I do? Just took the tip of that Mac 3 and slid it under the epiglottis and picked it up. Voila! Grade 1 view.

Why anyone uses a Miller blade ever is beyond me. Not that I can't intubate with a Miller blade just like any other airway ninja out there.
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I think you answered your own question. You got a much better view lifting the epiglottis. So, why not use a blade that was designed to lift the epiglottis?

I could argue, why ever use a MAC. I don't think I have ever heard of a case where someone had an IMPROVED view from switching to a MAC after a Miller. I'm sure it happens a lot - I just don't hear about it. It generally goes the other way.
 
Larger curve on a Mac 3?

Does our hospital order MAC blades from Haiti or something?

Look, a MAC 4 has a much bigger curve and requires a larger tissue displacement to see down the straight line.

See attached image. I have traced the lower edge of a Mac 3 and 4. In order to see from the eye to the tip in a straight line, Mac 4 required 2.1cm displacement, Mac 3 is 1.2 cm.
 

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I was told this concept by a very experienced anesthesiologist who had to review all the poor anesthetic outcomes in the Navy. He started looking at it because a very high percentage of the failed intubations were from MAC4.

Interestingly, the ones that love a MAC 4 in out institution are the CRNAs - thinking it is a better blade for the big people.
 
epidural man said:
Larger curve on a Mac 3?

Does our hospital order MAC blades from Haiti or something?

Look, a MAC 4 has a much bigger curve and requires a larger tissue displacement to see down the straight line.

See attached image. I have traced the lower edge of a Mac 3 and 4. In order to see from the eye to the tip in a straight line, Mac 4 required 2.1cm displacement, Mac 3 is 1.2 cm.
Click to expand...

Diagram is flawed because the line of sight is typically through the distal 1/3 of the blade only, not the entire blade. The MAC 4 provides extra length to firmly engage the vallecula with the blade tip in almost all patients. This was a frequent cause of failure with the MAC3...at least in my hands.
 
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nimbus said:
Diagram is flawed because the line of sight is typically through the distal 1/3 of the blade only, not the entire blade. The MAC 4 provides extra length to solidly engage the vallecula with the blade tip in almost all patients. This was a frequent cause of failure with the MAC3...at least in my hands.
Click to expand...

I don't think it is flawed, but could be. Show me a picture demonstrating your point.
 
nimbus said:
I'm no artist but this is fun.....View attachment 184630
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Your Mac 4 doesn't have near the depth and curve it should. If the MAC 4 was just a bigger blade without a difference in the distance between the greatest point of the curve, and the tip of the blade, then I would totally agree, and also it would correspond with your picture. Unfortunately, that isn't the case.

In fact, in your picture, your Mac 4 has less of a curve than your Mac 3 which doesn't correspond to reality at all. that is how the Mac 4 SHOULD be designed.
 
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epidural man said:
You Mac 4 doesn't have near the depth and curve it should. If the MAC 4 was just a bigger blade without a difference in the distance between the greatest point of the curve, and the tip of the blade, then I would totally agree, and also it would correspond with your picture. Unfortunately, that isn't the case.

In fact, in your picture, your Mac 4 has less of a curve which doesn't correspond to reality at all.
Click to expand...

I've looked at our Heine blades and the curves are very similar. I'll have to recheck on Monday. I'm a big Mac4 fan and use it for all adults but I know I'm in the minority.
 
On the Heine blades the curve at the distal end are identical.

Mac3 up front, mac4 behind.

image.jpg
 
Yes, I know. That is the point. in my picture they have the same curve as well. Since the Mac4 is so much larger , you need to use the blade different than you do a Mac 3. In other words, you have to displace twice the tissue to see the tip of the blade as demonstrated by my drawing. If you are to see the tip of the blade, on a MAC4, you have to get your seeing axis such that you are looking down only the last 3rd of the blade (as you pointed out).
 
In most patients the proximal end of the MAC4 is protruding outside the patient's mouth and is an irrelevant factor. It is used exactly as a Mac3. The distance from the lips to the vallecula is what it is. The curves are continuous on both blades. There is no "greatest point of the curve" on either blade. Nobody uses the sight line indicated in your picture because we do not have X-ray vision.

Occasionally in deep patients, you end up using all the length of the Mac4. The length is there when you need it.
 
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IM intensivist here, with 400+ icu or emergent airways. I am terrible with a Mac 3, and do very well with a mac 4-- even on little ladies. Go figure.
Can't explain this.
 
nimbus said:
In most patients the proximal end of the MAC4 is protruding outside the patient's mouth and is an irrelevant factor. It is used exactly as a Mac3. The distance from the lips to the vallecula is what it is. The curves are continuous on both blades. There is no "greatest point of the curve" on either blade. Nobody uses the sight line indicated in your picture because we do not have X-ray vision.

Occasionally in deep patients, you end up using all the length of the Mac4. The length is there when you need it.
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Everyone uses the straight line he/she drew, exactly BECAUSE we dont have xray vision... we can only see
In a straight line. That's why miller 2-3 are the most superior blades. Straight line of sight from the eye to the glottis. Least tissue you have to displace. Most direct view. That being said, I use Mac 3 on everyone cause it's easier haha, but I rescue with miller 2.


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risnwb said:
Everyone uses the straight line he/she drew, exactly BECAUSE we dont have xray vision... we can only see
In a straight line. That's why miller 2-3 are the most superior blades. Straight line of sight from the eye to the glottis. Least tissue you have to displace. Most direct view. That being said, I use Mac 3 on everyone cause it's easier haha, but I rescue with miller 2.


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I was responding to Epidural Man.

His illustration shows straight sight lines going THROUGH curved metal blades. That is not possible.

My illustration shows straight sight lines going UNDER the blade which is what happens in real life.
 
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In reviewing both illustrations neither are completely accurate nor do they clearly show the relevant factors so I've made a third, "combined" diagram.

I think it accurately depicts both the MAC3 and MAC4 blades, and a realistic sight line. It shows Epidural Man's point that the length of line A is significantly greater than the length of line B. But the picture also shows why that does not matter. Line B is actually common to both blades!

The distal 80-90% of a mac4 is identical to a full mac3 blade. There is nothing you can do with a Mac3 that cannot also be done with a Mac4. The Mac4 just gives you more length at the proximal end which helps you reach the occasional deeper glottic apertures of the giraffes and Herman Munsters.

Mostly I'm glad I'm not the only anesthesia geek who thinks about this stuff which will be irrelevant when AMCs replace all of us with robots.

image.jpg


To the OP....after 18 years of high volume, physician-only practice, I am still often close to the teeth. IMO it's okay as long as you are aware that you are close and don't scrape or apply force in the wrong direction.
 
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Anyone else try the reduced flange MAC? I hit the teeth less with this one. The part that always approaches the teeth is much smaller.

image.jpg
 
epidural man said:
I think you answered your own question. You got a much better view lifting the epiglottis. So, why not use a blade that was designed to lift the epiglottis?

I could argue, why ever use a MAC. I don't think I have ever heard of a case where someone had an IMPROVED view from switching to a MAC after a Miller. I'm sure it happens a lot - I just don't hear about it. It generally goes the other way.
Click to expand...

Do you see the fault of your own logic here?

And, if we're gonna talk anecdotes here, I've seen far more people struggle/fail with a Miller than a Mac. I've also seen far more injuries with a Miller. Of course, you can't tell Miller-blade-wielding CRNAs anything in the first place. That's a big part of the problem.
 
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