# Disposable ETT cuff manometer



## TransportJockey (Mar 20, 2018)

Looking for a small disposable manometer to keep in my work bag. The AG Cuffil looks good but I can't find pricing info or a purchase point. I do enough tubes the last two years that I'm interested in finding one. Plus I know my service looks at it as an unneeded expense


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## PotatoMedic (Mar 21, 2018)

A vet supply store listed them as 25 pounds, unknown if that is each or for a box of 10.  So looking at 50 dollars roughly.


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## PotatoMedic (Mar 21, 2018)

https://www.medida-shop.de/shop/de/...ntubation/9421/ag-cuffill-cuffdruckmessgeraet

If you feel like ordering in German.


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## ThadeusJ (Mar 21, 2018)

Here's one a little closer to home:   http://www.kalmed.net/PylantMonitor/Literature/tabid/154/Default.aspx


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## ISRDEU (Mar 22, 2018)

Hi there,

Try search of CUFFILL


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## TXmed (Mar 22, 2018)

AG cufill


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## TransportJockey (Mar 22, 2018)

ISRDEU said:


> Hi there,
> 
> Try search of CUFFILL


Hi there. You're an idiot if uou think I haven't tried that already


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## TransportJockey (Mar 22, 2018)

ThadeusJ said:


> Here's one a little closer to home:   http://www.kalmed.net/PylantMonitor/Literature/tabid/154/Default.aspx


I actually just got a email from them and it's not fda cleared yet for use in the US


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## TransportJockey (Mar 22, 2018)

TXmed said:


> AG cufill


That looks like the best option. I contacted the distributor to find an option for getting one or two. If the price is low enough maybe I can convince my bosses to get therm. 
Boundtree is asking 1k/bx though


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## CANMAN (Mar 22, 2018)

Why do you want disposable? Just for size?


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## TransportJockey (Mar 22, 2018)

CANMAN said:


> Why do you want disposable? Just for size?


And price. Those are 350 each


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## DrParasite (Mar 22, 2018)

If your service isn't providing them, and most places don't use them (for whatever reason), why do you want one?


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## DesertMedic66 (Mar 22, 2018)

DrParasite said:


> If your service isn't providing them, and most places don't use them (for whatever reason), why do you want one?


For the benefit of the patient? My service doesn’t supply coban or actual good quality chest seals. I supply both items because they will help me do my job and will benefit the patient.


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## DrParasite (Mar 23, 2018)

DesertMedic66 said:


> For the benefit of the patient? My service doesn’t supply coban or actual good quality chest seals. I supply both items because they will help me do my job and will benefit the patient.


So when your patient goes south, and the lawsuits get filed, and the investigation reveals that you are using equipment that is not supplied by your agency, you do realize that your agency (or more likely, their insurance company) is likely to place all the blame on you  (regardless of the fact that the reason the patient died had nothing to do with your personal supplies), because you were using unapproved and unauthorized equipment?  

If your medical director hasn't authorized its use on the ambulance (because if he or she had, it would be on the ambulance, so by default, all non-provided medications and equipment is not approved, unless explicitly stated otherwise), why are you using unauthorized  equipment?  Couldn't it be interpreted as working outside your proved scope of practice?

I mean, using your logic, I could bring my personal set of irons (flat headed ax and haligan married together), because I might need to force a door to get to my patient to gain access to my elderly patient who fell (which leads to better patient care) or I can work on gaining access to an MVA before the FD arrives (again, quicker access leads to better patient care).  Now if your agency provided you that equipment on to keep on the ambulance, that's a much different story.....


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## ThadeusJ (Mar 23, 2018)

A quick literature search revealed these studies for those who may have access to them.  You can get complications in as little as a few hours, leading to rupture into the esophagus.


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## Tigger (Mar 23, 2018)

DrParasite said:


> So when your patient goes south, and the lawsuits get filed, and the investigation reveals that you are using equipment that is not supplied by your agency, you do realize that your agency (or more likely, their insurance company) is likely to place all the blame on you  (regardless of the fact that the reason the patient died had nothing to do with your personal supplies), because you were using unapproved and unauthorized equipment?
> 
> If your medical director hasn't authorized its use on the ambulance (because if he or she had, it would be on the ambulance, so by default, all non-provided medications and equipment is not approved, unless explicitly stated otherwise), why are you using unauthorized  equipment?  Couldn't it be interpreted as working outside your proved scope of practice?
> 
> I mean, using your logic, I could bring my personal set of irons (flat headed ax and haligan married together), because I might need to force a door to get to my patient to gain access to my elderly patient who fell (which leads to better patient care) or I can work on gaining access to an MVA before the FD arrives (again, quicker access leads to better patient care).  Now if your agency provided you that equipment on to keep on the ambulance, that's a much different story.....


Classic EMS doomsday lines. Do you have any proof of this ever happening? Any examples? Maybe some relevant case law?

I'm sure not using an agency supplied stethoscope opens me up to incredible liability. I mean it's not like my agency approved it, how do they know I can even hear lung sounds??


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## DesertMedic66 (Mar 23, 2018)

Tigger said:


> Classic EMS doomsday lines. Do you have any proof of this ever happening? Any examples? Maybe some relevant case law?
> 
> I'm sure not using an agency supplied stethoscope opens me up to incredible liability. I mean it's not like my agency approve it, how do they know I can even hear lung sounds??


I typed up a response but this one is much more nice haha. 
Not all of our stuff is agency approved. Our medical director doesn’t say “you must have this type of EKG patches from this company”. Our company just gets the best deal they kind find from our supplier that the crews don’t complain about. 

I know some medics carry around cartoon bandaids for pediatric patients without any issue. The majority of people use their own stethoscope and more people are starting to carry the raptor shears. 

Heck, I’m one of the few racetrack certified medics we have and our medical director doesn’t know how to use some of the special equipment that we carry. The supervisors have literally said “if there is any piece of equipment that will help you do your job at the track just let me know and we will get it”. 

I know there are many cops and firefighters who carry small pieces of personal gear that they prefer to use. I’m not talking about bringing in my own LP15 to work.


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## Peak (Mar 23, 2018)

@Remi would probably be able to answer this, but is there really a big difference between using a specific cuff pressure compared to slowly inflating the cuff until you no longer have air leak and stopping right there? I have never personally seen a manometer used to measure cuff pressures in the ED, PICU, ICUs, or ORs.


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## VFlutter (Mar 23, 2018)

We just did some education on this so I am assuming we will be getting them at some point.

Our RTs checked cuff pressures once a shift in the ICU


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## Carlos Danger (Mar 24, 2018)

Peak said:


> @Remi would probably be able to answer this, but is there really a big difference between using a specific cuff pressure compared to slowly inflating the cuff until you no longer have air leak and stopping right there? I have never personally seen a manometer used to measure cuff pressures in the ED, PICU, ICUs, or ORs.



The modern high volume / low pressure ETT cuffs are designed such that if the tube is properly sized and the cuff is not overfilled, cuff pressures above about 20 are unlikely. 

The problems with picking an arbitrary number (24 has always been common) and using a cuff manometer to inflate to that number are that, 1) you might not need that much pressure, which means that while your cuff pressure is probably still safe, it may still be higher than it needs to be and 2) it may not be enough pressure, and an inadequately sealed tracheal cuff can cause more pressing concerns than tracheal ischemia.   

So yeah, I would agree that the minimal-occlusion pressure method (inflating until the leak is gone) is probably the best technique, especially with a hi-lo cuff on a property sized tube. The cuff pressure probably should be checked at some point but I wouldn't worry about it in the prehospital phase at all.


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## DrParasite (Mar 25, 2018)

DesertMedic66 said:


> Our company just gets the best deal they kind find from our supplier that the crews don’t complain about.


apples and oranges.   if your company is providing the equipment, than your agency has approved it's use.





DesertMedic66 said:


> The majority of people use their own stethoscope and more people are starting to carry the raptor shears.


So did mine... our policies clearly said that each person was permitted to use their own scope.





DesertMedic66 said:


> Heck, I’m one of the few racetrack certified medics we have and our medical director doesn’t know how to use some of the special equipment that we carry. The supervisors have literally said “*i**f there is any piece of equipment that will help you do your job at the track just let me know and we will get it*”.


if your supervisors/management/company/agency are providing that equipment, than they are permitting you to use it.  that's much different than bringing your own stuff from home and using it on the job.





DesertMedic66 said:


> I know there are many cops and firefighters who carry small pieces of personal gear that they prefer to use. I’m not talking about bringing in my own LP15 to work.


I know many EMS people that would carry expandable batons, handcuffs, flashlights, and couple that would carry their personal firearms, if their agency would allow them to.  carrying your own medical equipment is much different than carrying a personal tool to make your job a little easier.





Tigger said:


> Classic EMS doomsday lines. Do you have any proof of this ever happening? Any examples? Maybe some relevant case law?


sure.  I called up my agency's insurance agent (who, by his very nature, is a subject matter expert on insurance, and on what insurance policies cover), and asked if they would back me if I used unapproved equipment during my job.  They flatout told me no, because i would be operating outside the conditions set forth by my employer, which is what the insurance policy applies to.  They will cover me if I am doing my job, as specified by my employer, if I am following the guidelines set forth by my employer (which includes using the appropriate equipment, set forth by my employer).  If I am operating outside of those guidelines, than any liability would be my responsibility only, not the agency.

Why don't you do the same?  Get the company name, and or the agent, and ask if you can obtain non-company provided or approved equipment to use it on your patients.  Let me know what he says.





Tigger said:


> I'm sure not using an agency supplied stethoscope opens me up to incredible liability. I mean it's not like my agency approved it, how do they know I can even hear lung sounds??


The appropriate response is, "it depends." does your agency permit you to use a personal stethoscope?  meaning, do their written equipment/uniform requirements permit the use of personal scopes?  Most do.

If you didn't like the brand of IV catheters that your agency provided, could you order your own and use them on your patients?  What about NPAs?  If your agency uses combitubes as your BIAD, but you think they suck, would they have any objections to you ordering some Igel from the local medical supply company?


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## Carlos Danger (Mar 25, 2018)

DrParasite said:


> If you didn't like the brand of IV catheters that your agency provided, could you order your own and use them on your patients?  What about NPAs?  If your agency uses combitubes as your BIAD, but you think they suck, would they have any objections to you ordering some Igel from the local medical supply company?



Well, there's a big difference between invasive medical supplies that most individuals can't even legally purchase never mind use on their own, like an IV catheter or an LMA, and something like a stethoscope than anyone can buy in any corner drug store.

Not to mention the fact that liability depends first and foremost on the action actually _causing_ damages. How could using one's personal stethoscope instead of the ones provided by your agency ever be shown to be the proximate cause of a bad outcome? Especially when personal ones are typically higher quality than the cheapos that most EMS agencies provide. How much effort can you foresee a plaintiff's attorney devoting making that case?

Where does this reasoning end? Do individuals need to fear liability for using personal watches on duty to time drug administrations? Calculators on their phones to figure dosages? 

Can you provide an actual example of a time that an agency or one of their employees was found liable for damages incurred because an employee used a personal stethoscope or cuff manometer that wasn't authorized by policy?


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## DrParasite (Mar 25, 2018)

Remi said:


> Well, there's a big difference between invasive medical supplies that most individuals can't even legally purchase never mind use on their own, like an IV catheter or an LMA, and something like a stethoscope than anyone can buy in any corner drug store.


your right; I'm not the one who said anything about stethoscopes.





Remi said:


> Can you provide an actual example of a time that an agency or one of their employees was found liable for damages incurred because an employee used a personal stethoscope or cuff manometer that wasn't authorized by policy?


i've never heard of anyone ever using a personal cuff manometer.  

and I would imagine most agencies permit personal stethoscopes, in writing, in their written procedures.


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## DesertMedic66 (Mar 25, 2018)

DrParasite said:


> your right; I'm not the one who said anything about stethoscopes.i've never heard of anyone ever using a personal cuff manometer.
> 
> and I would imagine most agencies permit personal stethoscopes, in writing, in their written procedures.


To my knowledge my agency has zero protocol/policy about personal stethoscopes. The only thing that is required is for 1-2 stethoscopes be on the ambulance. It is really a not needed policy.


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## ISRDEU (Mar 25, 2018)

TransportJockey said:


> Hi there. You're an idiot if uou think I haven't tried that already


Sorry, I did not intend to offend you. Nevertheless, try Mercury.


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## ISRDEU (Mar 25, 2018)

TransportJockey said:


> I actually just got a email from them and it's not fda cleared yet for use in the US


510(k) Number K 122721


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## Tigger (Mar 26, 2018)

DrParasite said:


> apples and oranges.   if your company is providing the equipment, than your agency has approved it's use.So did mine... our policies clearly said that each person was permitted to use their own scope.if your supervisors/management/company/agency are providing that equipment, than they are permitting you to use it.  that's much different than bringing your own stuff from home and using it on the job.I know many EMS people that would carry expandable batons, handcuffs, flashlights, and couple that would carry their personal firearms, if their agency would allow them to.  carrying your own medical equipment is much different than carrying a personal tool to make your job a little easier.sure.  I called up my agency's insurance agent (who, by his very nature, is a subject matter expert on insurance, and on what insurance policies cover), and asked if they would back me if I used unapproved equipment during my job.  They flatout told me no, because i would be operating outside the conditions set forth by my employer, which is what the insurance policy applies to.  They will cover me if I am doing my job, as specified by my employer, if I am following the guidelines set forth by my employer (which includes using the appropriate equipment, set forth by my employer).  If I am operating outside of those guidelines, than any liability would be my responsibility only, not the agency.
> 
> Why don't you do the same?  Get the company name, and or the agent, and ask if you can obtain non-company provided or approved equipment to use it on your patients.  Let me know what he says.The appropriate response is, "it depends." does your agency permit you to use a personal stethoscope?  meaning, do their written equipment/uniform requirements permit the use of personal scopes?  Most do.
> 
> If you didn't like the brand of IV catheters that your agency provided, could you order your own and use them on your patients?  What about NPAs?  If your agency uses combitubes as your BIAD, but you think they suck, would they have any objections to you ordering some Igel from the local medical supply company?


Perhaps some research on logical fallacies would help, here's a primer. https://owl.english.purdue.edu/owl/resource/659/03/

Until then, I'll wait for some case law.


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## ISRDEU (Mar 26, 2018)

Michelle Eibell 

USA - Mercury Medical

11300 49th Street North,

Clearwater, Florida USA 33762-4807

Toll Free: (800) 237-6418 (USA only)

Tel: (727) 573-0088

Fax: (727) 571-3922


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## CWATT (Mar 26, 2018)

Peak said:


> @Remi would probably be able to answer this, but is there really a big difference between using a specific cuff pressure compared to slowly inflating the cuff until you no longer have air leak and stopping right there? I have never personally seen a manometer used to measure cuff pressures in the ED, PICU, ICUs, or ORs.



We check it on every intubated patient.



Remi said:


> The modern high volume / low pressure ETT cuffs are designed such that if the tube is properly sized and the cuff is not overfilled, cuff pressures above about 20 are unlikely.



I picked up a patient last week whose cuff pressure was about 60cmH20.


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## Carlos Danger (Mar 26, 2018)

CWATT said:


> I picked up a patient last week whose cuff pressure was about 60cmH20.


Clearly overfilled, then.


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## Brandon O (Mar 26, 2018)

Peak said:


> @Remi would probably be able to answer this, but is there really a big difference between using a specific cuff pressure compared to slowly inflating the cuff until you no longer have air leak and stopping right there? I have never personally seen a manometer used to measure cuff pressures in the ED, PICU, ICUs, or ORs.



I'd say it is more or less the standard of care in the ICU.


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## Peak (Mar 26, 2018)

Brandon O said:


> I'd say it is more or less the standard of care in the ICU.



We just deflate the cuff until you hear air leak or have increased leak on the vent, typically adding about 0.5-1 mL of air, and call it good. Our view is that if you have to use more air than the standard cuff volume then your tube isn't correctly sized or they is a different pathology (ARDS, et cetera) that is causing us to need so much pressure in which case we need to address that by changing our vent mode/settings, changing our medications, change other treatments like proning the patient, or considering ECMO as a gas exchange adjunct. We haven't had any problems with impaired tracheal perfusion (well, outside of the NICU but that is of course not relevant to cuff pressures) so I think we haven't really had a need to address cuff pressures in a more precise way. Granted I have only worked in hospital systems that have ECMO, jet vents, oscillators, et cetera and in the field (I never ran IFTs) cuff pressure typically wasn't high on my list of concerns if I tubed somebody.


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## Brandon O (Mar 26, 2018)

Peak said:


> We just deflate the cuff until you hear air leak or have increased leak on the vent, typically adding about 0.5-1 mL of air, and call it good. Our view is that if you have to use more air than the standard cuff volume then your tube isn't correctly sized



It's not really a matter of size. We don't select tube size to match trachea size, like fitting a hand into a glove, other than in a very general sense ("Can't seem to cram an 8.0 into this one, let's try smaller"). This is because the cuff molds to fit the surrounding airway. Since that may require a larger or smaller volume, cuff inflation volume is really not predictable. That's why pressure is a better endpoint.

I suppose you can argue that if you inflate to the correct pressure and are still seeing cuff leaks, then you need to upsize -- but as cuffs can usually be inflated to obscenely large volumes if you so desire, I'm not sure how true that is.

If your airway pressures are consistently exceeding the pressure in the cuff, then physics dictates that you will probably have some leak. Expunging this by inflating the cuff to unsafe pressures would not be defensible. Mucosal ischemia is not a common thing in this era, but that is largely because of these basic good practices, and for that very reason I think it would be hard to defend your system if you weren't following them and had a bad outcome.



> Granted I have only worked in hospital systems that have ECMO, jet vents, oscillators, et cetera and in the field (I never ran IFTs) cuff pressure typically wasn't high on my list of concerns if I tubed somebody.



It's not really a factor of vent strategy. Safe airway management stands on its own.

I agree that in the field this stuff is probably not generally necessary, and using a fingerometer on the balloon is probably reasonable.


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## Peak (Mar 27, 2018)

Brandon O said:


> It's not really a matter of size. We don't select tube size to match trachea size, like fitting a hand into a glove, other than in a very general sense ("Can't seem to cram an 8.0 into this one, let's try smaller").



I'm going to disagree with you on this. A tube that is too small will either need a higher ramp, more pressure, or increased duration of inspiratory/expiratory phase compared to a larger tube. This is certainly much more pronounced for say a 2.0mm vs 2.5mm than 6.5mm vs 8.0mm, but a 6'5" guy should certainly be getting a bigger tube than a 55 kg grandma.



Brandon O said:


> is because the cuff molds to fit the surrounding airway. Since that may require a larger or smaller volume, cuff inflation volume is really not predictable. That's why pressure is a better endpoint.



Just for the sake of clarity I want to reinforce that I do not endorse fully inflating the cuff with the manufacturer's printed volume. I prefer to inflate the cuff slowly while bagging the patient and to stop adding more volume to the cuff as soon as there is no audible evidence of air leak. Often this is a small fraction of the volume that the manufacturer has printed on the tube/packaging.



Brandon O said:


> If your airway pressures are consistently exceeding the pressure in the cuff, then physics dictates that you will probably have some leak. Expunging this by inflating the cuff to unsafe pressures would not be defensible. Mucosal ischemia is not a common thing in this era, but that is largely because of these basic good practices, and for that very reason I think it would be hard to defend your system if you weren't following them and had a bad outcome.



If your airway pressures are exceeding the pressures in the cuff, and your airways pressures are exceedingly high, then the cause of that increased airway pressure needs to be addressed. I would never simply further inflate a cuff because their airway pressures are higher, any good clinician should be assessing and treating the underlying cause (mucous plugs, pathological lung disease, inappropriate volumes, kinked tubing, et cetera). I don't think that inflating/deflating cuffs based on a physical assessment increases liability over using a manometer.

For the sake of argument am I at higher liability if I place an art line without ultrasound guidance if I could identify the anatomy without one? Am I at higher liability if I intubate a neo with direct laryngoscopy instead of using a glidescope? I don't think adding tools necessarily decreases risk or liability.



Brandon O said:


> It's not really a factor of vent strategy. Safe airway management stands on its own.



If your patient has an ineffective ventilation/respiration management then it needs to be addressed. There is much more that goes into gas exchange than simply the size of a tube, how a cuff is inflated, or how a tube is secured. Different pathological or physiological processes don't have a one size fits all vent setting, and sometimes that means changing your management so that you can better facilitate gas exchange.



Brandon O said:


> I agree that in the field this stuff is probably not generally necessary, and using a fingerometer on the balloon is probably reasonable.



I don't advocate for trying to figure out the pressure in the tube by pressing on the balloon. I can understand the potential desire for IFT crews for a manomoter, especially with the potential of scene/transport noise making a physical assessment more difficult, but I don't think that 911 only groups need one. When I was in fire I got one cabinet for medical equipment (on the engine anyway) and I can think of all kinds of stuff I would prefer to have, now that I'm doing more wilderness-ish stuff where we carry in everything ourselves ounces add up to pounds real quick. I do think that the gold standard should always be a good physical assessment, and given my experience in the medical field so far I don't think it would have been a benefit in my practice.


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## Brandon O (Mar 27, 2018)

Peak said:


> I'm going to disagree with you on this. A tube that is too small will either need a higher ramp, more pressure, or increased duration of inspiratory/expiratory phase compared to a larger tube. This is certainly much more pronounced for say a 2.0mm vs 2.5mm than 6.5mm vs 8.0mm, but a 6'5" guy should certainly be getting a bigger tube than a 55 kg grandma.



Yes, a tighter tube make life a little more annoying, requiring higher peaks, making it difficult to bronch, etc. The answer is to place the largest tube you can fit without needing one of those post-diggers. (Most folks can take an 8.0.) I suppose you could view this as matching the size to the patient, but in general it can be done empirically, at least in adults.



> Just for the sake of clarity I want to reinforce that I do not endorse fully inflating the cuff with the manufacturer's printed volume. I prefer to inflate the cuff slowly while bagging the patient and to stop adding more volume to the cuff as soon as there is no audible evidence of air leak. Often this is a small fraction of the volume that the manufacturer has printed on the tube/packaging.



Other than the approximate ballpark I would ignore the "recommended" volume as well (I have no idea what it says on the package for our tubes). I agree that cuff leak is an important endpoint to recognize, although we use the vent, which is more exact. But the other endpoint is cuff pressure.

I think the point is that you might conceivably have a cuff leak even in the presence of a hyperinflated cuff at unsafe pressure. This might be due to atypical airway anatomy or an imperfectly-positioned tube. While it should make sense that a "barely sealed" cuff-to-trachea interface should equate with low pressures, this should only be true if that interface is perfectly homogenous. Since that is not always true, there could be high and low points, equating to high pressures while still allowing a leak. (There was some talk of using "tapered" cuffs lately to try and match surfaces even better, which hasn't really panned out.)



> If your airway pressures are exceeding the pressures in the cuff, and your airways pressures are exceedingly high, then the cause of that increased airway pressure needs to be addressed.



Poor compliance is certainly suggestive of lung pathology, but mostly as a marker; we don't manage pressures (other than trying to achieve safe plateaus), we manage disease states.



> For the sake of argument am I at higher liability if I place an art line without ultrasound guidance if I could identify the anatomy without one? Am I at higher liability if I intubate a neo with direct laryngoscopy instead of using a glidescope? I don't think adding tools necessarily decreases risk or liability.



I don't think so yet, but we may be getting there. The missing link is data suggesting clear superiority in patient outcomes. There IS good data that ultrasound increases success and decreases complications in line placement, but not really that it affects many patient-centered outcomes like mortality, so you can still get away with blind placement. There is NOT clear data yet that VL is clearly superior to DL.

A good analogy might be central line placement in the IJ. While there is not, to my knowledge, a head-to-head study on this, everyone has pretty much abandoned doing these by the landmark approach, because they are usually extremely easy under ultrasound, whereas accidentally puncturing a carotid is very undesirable. That combination makes it pretty undefensible if you wreck a carotid when an ultrasound was waiting in the closet 20 feet away. Similarly, in resource-rich settings when the equipment and personnel are readily available, I think there is little to be argued against simple cuff pressure checks to prevent the really gnarly outcomes like tracheoesophageal fistulas.



> If your patient has an ineffective ventilation/respiration management then it needs to be addressed. There is much more that goes into gas exchange than simply the size of a tube, how a cuff is inflated, or how a tube is secured.



I would say these have next to nothing to do with gas exchange.


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## MSDeltaFlt (Mar 28, 2018)

Me, personally, minimal leak is good for prehospital.  When I have the ICU as an RT I like to use cuff pressure.  

As far as ETT's go, since this particular thread has evolved, I choose my ETT size based on 0.5 smaller than the largest tube that will fit.  That way you get the lowest intrapulmonary pressures possible and can use just enough air to inflate the cuff to get rid of any wrinkles on the bulb to prevent any hard edges on the inner lining of the trachea.  What that can also do on weaning (I know this is an EMS website and not an RT website and we do not wean in the field, but...) is to allow the patient to breathe around the tube when you're doing a leak test to assess spontaneous respirations just prior to extubation.

My personal anecdotal opinion is if you need to use a syringe larger that a 3cc or 5cc to inflate the cuff then your tube is too small.  Remember, tracheas are larger in diameter compared to ETT's than you might think.


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## Brandon O (Mar 28, 2018)

MSDeltaFlt said:


> As far as ETT's go, since this particular thread has evolved, I choose my ETT size based on 0.5 smaller than the largest tube that will fit.



I assume you mean this more as a general concept (aiming to place a tube a little smaller than one you think you'd have to cram in) than a practical one -- I assume you are not intubating by passing larger and larger tubes until you reach one that doesn't fit, then downsizing by one...


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## MSDeltaFlt (Mar 29, 2018)

Brandon O said:


> I assume you mean this more as a general concept (aiming to place a tube a little smaller than one you think you'd have to cram in) than a practical one -- I assume you are not intubating by passing larger and larger tubes until you reach one that doesn't fit, then downsizing by one...




Uh, negative, Ghostrider.  I'm referring to first pass scenarios.  As I mentioned before, tracheas are larger than most might realize.  Take me for example.  I am a 48yo male who is 5'10 1/2'' - 5'11" depending on how angry you make me.  And the inner diameter of my trachea is larger than the outer diameter of a 10.0 ETT.  People need to treat tracheas in the same way they treat veins.  You go larger for a reason.  Advocate for your patient and give them the most flow with the lowest pressures possible.

Drop it like it's hot.


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## ThadeusJ (Mar 29, 2018)

MSDeltaFlt said:


> You go larger for a reason. Advocate for your patient and give them the most flow with the lowest pressures possible.



The maximum airflow that can pass through a tube is an inverse function of the radius _to the power of four._ In English, that means that if you reduce the radius of a tube by half, the flow that can pass through the tube is cut 16 times (1/16).  For patients that have respiratory issues to begin with (e.g. COPD), trying to get them to breathe spontaneously through the tube prior to extubation can be a non-starter as the resistance it way too high.  I don't know how many times I had to explain to a doctor that if they could breathe through the pea shooter they put in, the patient wouldn't be in the hospital to begin with.


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## VFlutter (Mar 29, 2018)

That's what SBT with Pressure Support is for....


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## MSDeltaFlt (Mar 29, 2018)

ThadeusJ said:


> The maximum airflow that can pass through a tube is an inverse function of the radius _to the power of four._ In English, that means that if you reduce the radius of a tube by half, the flow that can pass through the tube is cut 16 times (1/16).  For patients that have respiratory issues to begin with (e.g. COPD), trying to get them to breathe spontaneously through the tube prior to extubation can be a non-starter as the resistance it way too high.  I don't know how many times I had to explain to a doctor that if they could breathe through the pea shooter they put in, the patient wouldn't be in the hospital to begin with.





VFlutter said:


> That's what SBT with Pressure Support is for....



Yes, with the advancement of modern microprocessor ventilators, T-pieces are no longer needed prior to extubation.  However, with the smaller tubes the PIP's are unnecessarily high and give false readings as to what is going on in the pulmonary tissue.  The lower the pressures + the easier the flow = the less resistance = the less chance for barotrauma.

You choose you ETT size just like you choose your IV cath size.  Get as big as you can get for very specific reasons.

It is never a "go big or go home" philosophy.  It's more like a "if it'll fit it stick it" but just one size smaller that the absolute largest that will fit.  After SBT's they sometimes like to deflate the cuff to make sure move enough air around the tube just prior to extubation.  If after a few breaths they're still doing good, have them cough as you pull it.  But while they're intubated bigger is better.


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## Brandon O (Mar 29, 2018)

MSDeltaFlt said:


> However, with the smaller tubes the PIP's are unnecessarily high and give false readings as to what is going on in the pulmonary tissue.  The lower the pressures + the easier the flow = the less resistance = the less chance for barotrauma.



I would put this a little differently. Elevated peak pressures due to a small tube have very little relevance to the lungs at all; it is mostly annoying because your alarms will need adjusting (and the same people who get freaked out by high blood pressures will call you a lot). You can force flow through a pretty teeny tube by generating very high pressures, which our vents can do.

However, you can't force the patient to exhale, which is a passive process. So a smaller tube may limit your achievable respiratory rate, lest you cause breath stacking. It also makes pulmonary toilet more difficult (harder to fit down a bronch, more likely to get something gnarly like a mucus plug).


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## MSDeltaFlt (Apr 2, 2018)

Brandon O said:


> Elevated peak pressures due to a small tube have very little relevance to the lungs at all; it is mostly annoying because your alarms will need adjusting (and the same people who get freaked out by high blood pressures will call you a lot). You can force flow through a pretty teeny tube by generating very high pressures, which our vents can do.



You'll have to adjust alarms unnecessarily.  You CAN force flow through a teeny tube by generating very high pressures by modifying your vents' flow rates... UNNECESSARILY.  Thus masking what is truly going on within the pulmonary system.  Increasing flow rates and generating higher PIP's increases barotrauma.  Choosing to do this increases ventilator hours and hospital stay when it could have come to that merely by choosing a larger ETT.

An ounce of prevention is worth a pound of cure.


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## Brandon O (Apr 2, 2018)

MSDeltaFlt said:


> You'll have to adjust alarms unnecessarily.  You CAN force flow through a teeny tube by generating very high pressures by modifying your vents' flow rates... UNNECESSARILY.  Thus masking what is truly going on within the pulmonary system.  Increasing flow rates and generating higher PIP's increases barotrauma.  Choosing to do this increases ventilator hours and hospital stay when it could have come to that merely by choosing a larger ETT.
> 
> An ounce of prevention is worth a pound of cure.



Of course you're right that there's no sense in making trouble if it can be avoided. But I'm not sure I agree that elevated peak pressures due to a small tube increase the risk of barotrauma. Those pressures are not occurring in the lungs; they are solely upstream of the tube.


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## MSDeltaFlt (Apr 3, 2018)

But the increased flow does.

Think of it like this.  When you wash your car, can you get more dirt off (do more damage to the dirt) with the water gently flowing out of the water hose or when you hold your thumb over the end increasing the back pressure to increased the flow?

Your lungs are just as pink as the inside of your mouth.  They don't get that pink by being tough.  They get that pink by being that delicate.


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## Brandon O (Apr 3, 2018)

MSDeltaFlt said:


> But the increased flow does.



This is an interesting idea, and not one that I've seen supported in the literature (i.e. that higher flows are associated with more lung injury). I suppose one could argue that the more rapidly you expand alveoli, the more damage you cause them, but I don't know. Most "atelectrauma" is probably caused at the moment of recruitment (the shear force induced when you snap them open from fully collapsed), not when you expand them from small to large. If you have some data on this I'd be curious to see it.

But anyway, I think it's immaterial. A smaller tube does not dictate higher flow rates.

- In a volume mode, flow is fixed and set by the user. The vent will generate whatever peak pressure is needed to maintain the desired flow. Higher peaks will be needed to achieve the same flow, if the tube is smaller, but as discussed, this pressure is not reflected in the lungs, so it is mostly immaterial.

- In a pressure mode, flow is dynamic and adjusted by the vent to achieve the target pressure. With a very tight tube, this would actually mean that you will reach your pressure at a LOWER flow (since it's bottlenecking against the small conduit), which I suppose could mean your inspiratory cycle could be delayed and (if inspiratory time is not increased to accommodate it), may mean that flow has not dropped to zero by the end of expiration. This is a bit theoretical as I'm not sure if I've ever seen this happen.


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## MSDeltaFlt (Apr 14, 2018)

https://www.sciencedirect.com/topics/nursing-and-health-professions/peak-inspiratory-pressure

Barotrauma
Elevated peak inspiratory pressures and mean airway pressures have been implicated as being traumatic to the lung parenchyma. High peak inspiratory pressures are associated with pneumothorax, whereas elevated mean airway pressures are associated with pneumothorax and reduction in cardiac output.73 It is not clear whether high peak inspiratory pressures are a primary or secondary phenomenon associated with the generation of pneumothorax. It is possible that nonhomogeneous lung ventilation (areas of poorly ventilated and well-ventilated alveoli in close proximity) results in pressure gradients across the interstitium and alveoli and the potential for rupture. However, it is a common clinical strategy to try to limit peak inspiratory pressure and mean airway pressure as much as possible.

http://journal.chestnet.org/article/S0012-3692(16)34065-X/fulltext

In our study, increased levels of PIP and PEEP were associated with the development of all forms of barotrauma. The association of PIP with PTX has been reported previously, with levels of greater than 35 to 50 cm H2O being associated with higher risk of both PTX and ME.2, 11, 12, 13 

http://www.frca.co.uk/Documents/100308 Physics of flowLR.pdf

Ventilation
The principles here are similar to those with the intravenous cannulae. Flow through
a tracheal tube is laminar so the Hagan-Pouseuille formula applies. If a smaller
diameter tracheal tube is used, then flow will be significantly reduced as it is
proportional to the forth power of the diameter, unless the pressure gradient is
increased (changing the tube from an 8mm to a 4mm may reduce flow by up to
sixteen-fold!)

I've been knowing this for almost 30 years.  When you use smaller tubes you get used to seeing higher PIP's.  These new microprocessor mechanical ventilators may be able to compensate to an extent flows and some PIP's.  But increased PIP's are related to barotrauma.  And when you have higher PIP's at the onset due to smaller tubes you mask increased PIP's that can occur with barotrauma.

What I'm saying is go big at the beginning.  A patient's trach is larger than you might think.  And don't get me wrong.  I don't have a "Go big or go home" philosophy.   I fully understand that you can get what you can get.  But what I'm saying is, "If it'll fit it stick it".

If you have an elective intubation set out three ETT's.  One you know you can usually get, one you'd like to get, and one a size smaller "just in case" their trachs are smaller than expected.

My personal philosophy is this.  If you have to use more than a 5cc syringe to obtain minimal leak then odds are you could have used a larger ETT.


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## MSDeltaFlt (Apr 14, 2018)

Brandon O said:


> This is an interesting idea, and not one that I've seen supported in the literature (i.e. that higher flows are associated with more lung injury). I suppose one could argue that the more rapidly you expand alveoli, the more damage you cause them, but I don't know. Most "atelectrauma" is probably caused at the moment of recruitment (the shear force induced when you snap them open from fully collapsed), not when you expand them from small to large. If you have some data on this I'd be curious to see



I'll grant you that one.  The amount of expansion from increased flow rates are a problem.


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