# Does Size Matter?



## VentMonkey (Aug 21, 2019)

I wanted to ask this question to some of the forums airway heavyweights, @E tank, @Remi, and a couple others whose names escape me right now. 

Simply put: Does the size of an ETT relative to an adult patients size truly matter? 

The reasons I ask are A) the last few inductions that I’ve participated in I’ve asked for an ETT only to find myself on the receiving end of a standard 7.0 with otherwise healthy adult males. Both of which were corrected with an 8.0 and a look by the ground crews as if this was being done punitively. 

I assure you this is not what I was taught, nor how I have learned to evolve my thought process regarding _proper_ airway management.

And B) to my understanding, the wrong sized ETT is often replaced with the right sized one (i.e., the appropriate size for the patient at hand barring any anatomical challenges). Why cause double the risk or harm?

Is it really being skimmed over in the majority of paramedic schools that “hard plastic” is all that matters, but not the proper size for right reasons to include airway pressures, and resistance met on ventilators and such? 

Anyhow, as usual all comments and opinions are welcomed. I figured the CC subforum could use a bump. And yes, the thread title is absolutely click bait.


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## CALEMT (Aug 21, 2019)

I clicked on this not knowing what to think... needless to say I am relived yet slightly disappointed.


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## StCEMT (Aug 22, 2019)

I know my normal is 7.5 men and 7.0 women with a back up tube one size down set out. I'm not sure how much difference an 8 would make over the 7.5 I usually do, but I'm curious and going to look this up now.


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## DrParasite (Aug 22, 2019)

Bigger is better, as it allows a larger amount of air to be passed from the lungs to the outside.  think burn patients with airway swelling, facial trauma, or even tubing a cardiac arrest with a BVM application; the larger the tube, the less air restriction you have.  This is, of course, assuming you don't commit massive amounts of trauma putting the tube between the vocal cords.  That's why several calculations exist to get the approprate size, and providers still need to use good judgement.

Of course, is there that much of a difference between a 7.5 and an 8?  maybe half a milliliter?  is anyone going to really notice it?  probably not.

But compare a 7 for an adult vs a 3.5 for an infant......

From a practical standpoint, does it really matter?  I doubt it.  I'm sure there is some mathematical calculation that incorporate friction loss from air move in the tube plus the volume changes of the tube diameter vs your regular trachea....  but I don't know, nor do I have the desire to look it up.

Maybe it's different in CCT/HEMS/Anesthesia/ER, but I was always taught  if the airway has been secured, and the device is doing it's job, and there are no complications, why do you want to mess with it?


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## mgr22 (Aug 22, 2019)

Assuming airflow isn't turbulent, airway resistance is inversely proportional to the 4th power of the airway radius. That means resistance through an 8.0 ETT is about 25% less than it would be through a 7.5 tube. I'm not sure how important that 25% difference is. I guess it depends partly on how long the tube is in.


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## silver (Aug 22, 2019)

The difference in airway resistance on the vent is trivial between the sizes. However, in an ICU patient who you are trying to do a spontaneous breathing trial on anywhere you can get some extra help to have them succeed in being extubated is beneficial. The increased luminal diameter decreases the resistance and work of breathing which the patient may have to demonstrate ability to breath against comfortably for hours (possibly multiple days in a row). Also mind you the functional internal diameter gradually decreases with time as junk builds up inside.

Additional consideration is the ability to suction and bronchoscope through the tube. For example, our RRTs have a suction catheter that is designed to do  broncheoalveolar lavage which needs at least a 7.5 tube and a classic adult standard bronchoscope needs a 7.5-8.0 tube as well.

That being said put in the tube that you think is most appropriate, safest and best for the situation you are in at that moment. Think you’ll have trouble quickly putting a 7.5 in a tiny woman? Just put a 7.0 and if needed someone will just exchange it later.


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## Carlos Danger (Aug 22, 2019)

As has been pointed out, larger tubes present much less resistance to flow, which is important during weaning and can make ventilation a little less challenging in some scenarios. It is easier to suction and bronch through a larger tube, as well.

Are any of these a concern during an emergency in the field? Not really. Your priority then is to safely secure the airway in a challenging setting. Place the biggest tube that you can EASILY place, and if the ICU docs want a bigger one later, they can simply swap it out. They have a lot more help and resources there then you do in the field. 

An 8.0 will easily fit the vast majority of adult males and a 7.0 or 7.5 will easily fit most adult females. Anyone who thinks placing a little larger tube is punitive or mean does not apparently  understand the role of the induction agent or post-intubation sedation.


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## GMCmedic (Aug 22, 2019)

When I went through medic school, I was taught 7.0 for males and 6.0 for females. Ive evolved my thinking, but I doubt many of my classmates or even my instructors have.


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## VFlutter (Aug 22, 2019)

I usually place an 8.0 or 7.5 as they are able to be used for bronchoscopy, easier to suction, and less likely to get plugged with mucus or blood clots. Smaller tubes also have a tendcy to kink easily with movement. But as Remi said you get what ever tube you can easily pass and let the ICU worry about an exchange later if needed. 

Had a couple OR transfers with 10.0


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## KingCountyMedic (Aug 22, 2019)

7.5 adult males, 7.0 adult females is usually what I go with. We used to carry all the way up to 9.0 but never used them much. Lube the tube and pass it gently. Bigger is not always better. An Bougie is also quite nice for ensuring a nicely placed tube. I had a friend who's wife was a professional singer that needed emergent intubation and someone muscled in an 8.0 in the field and her song voice was forever messed up. "Do no harm"


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## Peak (Aug 22, 2019)

Just a few thoughts. 

When we get kids it is pretty common that we have to exchange their uncuffed tubes for cuffed ones, even in some premies. The pressures that they require on a conventional vent, jet, or oscillator necessitates a cuffed tube. This isn't to say that EMS, the transport team, or the outside hospital was wrong but our treatment plan (and risks/benefits) are very different than theirs. I don't go around complaining that an OSH general ED doc put a uncuffed 3.0 in a kid when we put in a 3.5 cuffed, we are all trying to do the best we can to stabilize patients.

The same goes for some adult tubes. We often have to exchange tubes for what ever reason (typically the cuff won't hold air), and so we may replace a plain tube with a tube with subglotic suction. Again it doesn't mean the original tube was wrong or bad, but that we want something better for how we are going to manage the patient.

Large tubes do not come without risk. They are more prone to failed attempts, are more likely to cause airway trauma. 

If I can vent a pretty chunky toddler with downs with a cuffed 3.5 (which has been a unfortunate reality multiple times), you can vent most adults adequately with a 6 or 6.5. A larger tube may provide less airway resistance but for most adults that amount is pretty trivial, and I'd far rather have a 6 placed in one attempt in the field than a patient with a swollen bloody airway. It's so easy to exchange adult airways that I don't necessarily thing arguing for the ICU when considering field placement is a strong selling point. I don't think placing a larger tube in an adult is necessarily bad, but it isn't the only way to manage an airway.

I think that most EMS programs fail the patient  after they get intubated, bagging a patient with a self inflating bag rarely gives the results we think it does, especially since most of the ones out in the field don't come with peep valves. I think a lot of traction can be gained by using a flow inflating bag, but even better is a good transport vent where you really can control their pressures, volume, I time, and so on. I would also consider the medication management of the patient, if a patient needs sedation because they are fighting a 7, having dropped an 8.5 isn't going to have changed that. If the patient needs a paralytic or inline treatment that needs to be considered too.


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## Carlos Danger (Aug 22, 2019)

Peak said:


> I think that most EMS programs fail the patient  after they get intubated, bagging a patient with a self inflating bag rarely gives the results we think it does, especially since most of the ones out in the field don't come with peep valves. I think a lot of traction can be gained by using a flow inflating bag, but even better is a good transport vent where you really can control their pressures, volume, I time, and so on.



It's been quite a while since I've seen a BVM that didn't come with a PEEP valve attached. I'm sure they are around, but I'm not sure it's accurate to say that "most of the ones out in the field" lack them.

OTOH, I've never seen a flow-inflating bag on an EMS unit, and I'm curious what traction you think they might provide. Every guideline I've ever seen that mentioned them specifically names them as inappropriate for resuscitation.


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## Peak (Aug 23, 2019)

Remi said:


> It's been quite a while since I've seen a BVM that didn't come with a PEEP valve attached. I'm sure they are around, but I'm not sure it's accurate to say that "most of the ones out in the field" lack them.
> 
> OTOH, I've never seen a flow-inflating bag on an EMS unit, and I'm curious what traction you think they might provide. Every guideline I've ever seen that mentioned them specifically names them as inappropriate for resuscitation.



I haven't seen many agencies that have bags with peep valves, and our flight medics who moonlight on the streets always 'borrow' them since the various services they work on don't have them. 

You can't feel compliance as well with a self inflating bag, you can't feel the patient start to take a breath, you have poor tactile feedback about how much gas you are actually squeezing in, you have no idea what fio2 you are actually giving the patient (nor can you flow nitric although that isn't a think for most EMS providers), peep is limited to whatever options are preset, without a manometer you don't know what your pips are. 

Our pediatric and neonatal teams use flow inflating bags prehospital (including when the pads team picks up adult congenital hearts), and we use them in all of the pediatric hospital from the ED to anesthesia to the units. We have some self inflating bags on the code carts for back up, but our policy dictates the preferential use of anesthesia bags, the other pediatric referral system in town has the same policies and practice.


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## VentMonkey (Aug 23, 2019)

Good stuff so far, all. I’m enjoying the dialogue.

@Peak my service carries PEEP valves, and to my knowledge it’s a CAMTS requirement. Obviously, I can’t speak your local HEMS shops.

Perhaps my need to assist in predicting  the patients clinical course has caused me to raise this question, and many others like it to myself.

I just figured, simply put, it is one of many things we can do to ensure patient comfort on our end in the field.

And, when logically explained, display what makes us, in the field—you know? The ones always whining about ETI—worthy of sitting at the “big boy” table with regards to advanced airway management discussions.

I feel that there’s still something to be said for clinical foresight in our field.

Carry on, please...


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## Carlos Danger (Aug 23, 2019)

Peak said:


> I haven't seen many agencies that have bags with peep valves, and our flight medics who moonlight on the streets always 'borrow' them since the various services they work on don't have them.
> 
> You can't feel compliance as well with a self inflating bag, you can't feel the patient start to take a breath, you have poor tactile feedback about how much gas you are actually squeezing in, you have no idea what fio2 you are actually giving the patient (nor can you flow nitric although that isn't a think for most EMS providers), peep is limited to whatever options are preset, without a manometer you don't know what your pips are.
> 
> Our pediatric and neonatal teams use flow inflating bags prehospital (including when the pads team picks up adult congenital hearts), and we use them in all of the pediatric hospital from the ED to anesthesia to the units. We have some self inflating bags on the code carts for back up, but our policy dictates the preferential use of anesthesia bags, the other pediatric referral system in town has the same policies and practice.



I'm well aware of the advantages that flow-inflating bags provide, since I actually use them multiple times a day, but I'm also aware of the disadvantages, and I highly doubt any of the things you mentioned translate to improved outcomes. They take significantly more skill to use and many of the advantages they provide are obviated by simple Etc02 and Sp02 monitoring.

PEEP valves and manometers are widely available for use with regular BVM's, and I don't think I've seen a BVM without a PEEP valve in at least 10 years, and they are mostly adjustable from 0-20, so I'm not sure what you are talking about when you say they are "limited to whichever options are preset".

The bigger question is, if you can't get agencies to use PEEP valves with their BVM's, how are you going to get them to use a Mapeleson circuit, since they are much more complex and harder to use?

There are reasons why both the AAP and AHA recommend against the use of them for resuscitation.

Also, the question was about general prehospital use of adult-sized tubes, not special neonatal transport of kids with tricuspid atresia or HLHS.


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## Peak (Aug 23, 2019)

Remi said:


> I'm well aware of the advantages that flow-inflating bags provide, since I actually use them multiple times a day, but I'm also aware of the disadvantages, and I highly doubt any of the things you mentioned translate to improved outcomes. They take significantly more skill to use and many of the advantages they provide are obviated by simple Etc02 and Sp02 monitoring.
> 
> PEEP valves and manometers are widely available for use with regular BVM's, and I don't think I've seen a BVM without a PEEP valve in at least 10 years, and they are mostly adjustable from 0-20, so I'm not sure what you are talking about when you say they are "limited to whichever options are preset".
> 
> ...



Most people grab the BVM, hook it up to oxygen, and squeeze. Most people don't adjust much, but then it somewhat works by just squeezing it. It is 'idiot proof' but that also means people over simplify its use.

Again, apparently you work in an area where crews have peep vaves, that isn't the way it is here. Flight crews have then but that's about it. I highly doubt the use is really all that widespread across the country. I guess we could open up a poll to see how many street cars are carrying them, one of us is probably going to be surprised; but either way there are still some massively large agencies not carrying them. 

How many codes do you actually run strictly by ACLS/PALS/NRP algorithms? Those recommendations are for the lowest common denominator, the person who sees one code every couple of years if that. Even for patients who present with pretty common disease states the algorithms underperform.

I still take care of adults (and not just the congenital program), and I understood the question. Adult patients can still have very complicated cardiac, pulmonary, or airway disease and live outside the hospital; those patients are encountered by EMS daily across the country. If they have poor management on the way to the ED, whether it be five minutes or several hours. I've had plenty of patients who were poorly managed prehospital and had devastating outcomes, and many who had great outcomes and their EMS care is part of the reason they were able to walk out without deficits.


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## Carlos Danger (Aug 24, 2019)

Peak said:


> Most people grab the BVM, hook it up to oxygen, and squeeze. Most people don't adjust much, but then it somewhat works by just squeezing it. It is 'idiot proof' but that also means people over simplify its use.
> 
> Again, apparently you work in an area where crews have peep vaves, that isn't the way it is here. Flight crews have then but that's about it. I highly doubt the use is really all that widespread across the country. I guess we could open up a poll to see how many street cars are carrying them, one of us is probably going to be surprised; but either way there are still some massively large agencies not carrying them.
> 
> ...



I'm just still just curious what "traction" you think can be gained by EMS switching to the use of a mapleson circuit. 

I would agree that a lot of EMS people aren't good at ventilating with a BV device, but I think it has more to do with environmental factors and lack of training than it does the device itself. BVM's aren't perfect but they do a perfectly adequate job when used properly. Even when used non-optimally, I don't think we are seeing lots of patients harmed by use of them.   

More importantly, I'm not sure how swapping one device that people have a hard time using properly for a more complex device that they are certain to have a HARDER time using properly is going to help in any way.


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## CbrMonster (Aug 24, 2019)

I know the hospital I did my clinical rotations at preferred an 8.0 on every as they could do iirc bonchoscopies through the Et tube if it was 8 or larger. I know it had something to do with equipment physically fitting down the tube at their facility.


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## Peak (Aug 24, 2019)

Remi said:


> I'm just still just curious what "traction" you think can be gained by EMS switching to the use of a mapleson circuit.
> 
> I would agree that a lot of EMS people aren't good at ventilating with a BV device, but I think it has more to do with environmental factors and lack of training than it does the device itself. BVM's aren't perfect but they do a perfectly adequate job when used properly. Even when used non-optimally, I don't think we are seeing lots of patients harmed by use of them.
> 
> More importantly, I'm not sure how swapping one device that people have a hard time using properly for a more complex device that they are certain to have a HARDER time using properly is going to help in any way.



It's a better device that provides better respiratory support, whether it is just bagging a dead person or providing more advanced strategies. A skilled clinician can mimic most ventilatory stratagies (with the exception of oscillators/jets, and yes they are used on adults) with a flow inflating bag. 

I agree that a flow inflating bag is much more difficult to use than a BVM, but you also can't half a** it. You have to be competent or it doesn't work. 

I think that in some ways it forces the clinician to stop and pay attention. It forces a level of competency that broadly speaking doesn't exist with a self inflating bag. 

Yes, if I hand someone a flow inflating device without training then it will not be effective. Like anything from a new stretcher to a new monitor it requires training. 

Self inflating bags are like the old ferno 30s (and some large agencies still use them). It's an old ideal that kinda works, but there are many more complicated and better options out there. For some reason people in EMS are happy to save their backs, but not to look at being able to better manage the basic airway.


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## Tigger (Aug 29, 2019)

Remi said:


> It's been quite a while since I've seen a BVM that didn't come with a PEEP valve attached. I'm sure they are around, but I'm not sure it's accurate to say that "most of the ones out in the field" lack them.
> 
> OTOH, I've never seen a flow-inflating bag on an EMS unit, and I'm curious what traction you think they might provide. Every guideline I've ever seen that mentioned them specifically names them as inappropriate for resuscitation.


By the same token I have never once worked on an ambulance that had BVMs with a PEEP valve. I carry one in my bag of "things the old school medics won't buy for the ambulances."

I try for 8.0 in adult males and 7.5 in females. The anesthesia folks we did rotations with were the ones that planted that idea in my ead, though I was not smart enough at the time to ask why.

Also it is somewhat more challenging to use anything bigger than a 7.5 in the channeled KingVision blades.


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## Carlos Danger (Aug 29, 2019)

Tigger said:


> By the same token I have never once worked on an ambulance that had BVMs with a PEEP valve. I carry one in my bag of "things the old school medics won't buy for the ambulances."



That’s interesting and unfortunate. I’m pretty sure we had them on my first EMS job in the mid 1990’s and every place I’ve been since then.


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## DesertMedic66 (Aug 29, 2019)

Remi said:


> That’s interesting and unfortunate. I’m pretty sure we had them on my first EMS job in the mid 1990’s and every place I’ve been since then.


My experience is the same as Tiggers. I have not encountered any agency in my area, except maybe Hall ambulance, that carries PEEP valves.


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## Tigger (Aug 29, 2019)

Sadly my full time job does not have vents either. Even the disposable SureVents we have at AMR can provide PEEP at least. We don't have video scopes either, so I've been using more 8.0 tubes here and honestly have not had any issues with the extra 0.5mm.


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## VentMonkey (Aug 29, 2019)

DesertMedic66 said:


> My experience is the same as Tiggers. I have not encountered any agency in my area, except maybe Hall ambulance, that carries PEEP valves.


To be fair, we only have them at CCT. 

@Remi I haven’t seen any in the prehospital environment out here in Cali over the past couple of decades. Maybe it’s a regional thing?...


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## MSDeltaFlt (Oct 29, 2019)

VentMonkey said:


> I wanted to ask this question to some of the forums airway heavyweights, @E tank, @Remi, and a couple others whose names escape me right now.
> 
> Simply put: Does the size of an ETT relative to an adult patients size truly matter?
> 
> ...



With the advancement of powerfully and technologically advanced microprocessor ventilators, the size of the ETT is pretty much made moot.  There were days when it was a major concern with T-piece trials.  Yes I am that old.  Took me forever to figure out how to hook up an H valve on my MA-1 for weaning.  But those days are pretty much gone the way of the Dodo.  

But as for me, my personal preference is "if it'll fit it stick it".  And I use that philosophy for adveolar recruitment.  Laminar flow is better that turbulent flow.  The lowest possible PIP's are always better.  Not to mention utilizing the least amount of air to fully inflate to cuff (3-5cc) for minimal leak is always beneficial as well.  I love 9's and 10's.  But I'm also not stupid.  If all I can get is a 7, I'll drop a 7.

Trach's tend to be larger in diameter than some might realize.  Go big.  Have a one size smaller as a back up right beside it just in case it won't fit.


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