Jay K

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Working with a locums CRNA today, and observed that she fills her endotracheal cuffs with lidocaine; Claims it promotes smoother extubation w/ less cough. New to me.

Found this:
http://www.anesthesia-analgesia.org/content/94/1/227.full

Anybody do this? Many of my partners and CRNA's use LTA's. I didn't use them very much in training and don't make it a regular practice myself.

Concerns with this practice? (filling cuff w/ lido)

Always willing to put a new technique under my belt for that special situation, but was wondering what others thought.
 

urge

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Old news. Haven't been impressed by it.

Give it try yourself. Don't believe the studies. Believe your own eyes. Did the patient buck?

BTW, the LTA is ******ed unless the case is under 20 min... in which case you will probably put an LMA... Mucosal lidocaine does not last long.
 
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Gimlet

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Concerns with this practice? (filling cuff w/ lido)
This is probably overly cautious, but would anyone be be worried about vocal cord trauma from accidental extubations with a liquid-filled cuff? Personally, I would rather have a cuff filled with compressible air be ripped through my larynx when somebody trips on the circuit than an incompressible lidocaine-filled balloon that might avulse my vocal folds.

Along the same lines, what about the cuff pressure in a liquid vs. gas-filled cuff? Would you be more likely to cause damage to the tracheal mucosa in a long case with a lidocaine-filled cuff?
 

dhb

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Doesn't work if i recall correctly the only valid measure is to coat the ETT with dexamethasone gel.
 

pgg

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BTW, the LTA is ******ed unless the case is under 20 min... in which case you will probably put an LMA... Mucosal lidocaine does not last long.
I had an attending who would take a premanufactured lidocaine LTA, use it to reconstitute an ampule (20 mg) of tetracaine, put the mix back into the LTA and use that. It definitely lasted longer ... but not hugely so.
 

Planktonmd

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Filling endotracheal tube cuffs with a liquid instead of air will most likely increase the pressure on the tracheal mucosa for little or no added benefit.
These cuffs are meant to be high volume low pressure cuffs and if we fill them with anything other than air we are most likely altering that desirable characteristic.
 

lushmd

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I've done this a few times so far (for CEAs) and it seemed to smoothen emergence/extubation (albeit this is admittedly a limited sample size). Per one of my attendings, one key is to fill the cuff with lidocaine a couple of hours prior to intubation to allow lidocaine to permeate through the plastic of the cuff. Other options include LITA tubes or administering lidocaine through the ETT at the end of the case (as discussed in a previous thread). As urge mentioned, LTAs are really only effective for short cases.
 
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Hi, Jay. I used to do this all the time (when I did longer cases). It is important that you add NaHCO3 to the lidocaine mix, otherwise very little lidocaine actually crosses the cuff membrane. This was confirmed in an in vitro study. The other benefit is that in long cases where you use N2O, the cuff pressure doesn't go up as much. There are at least 5-10 papers on lidocaine in the cuff on pubmed, and each uses a different conc/volume of lidocaine and NaHCO3. It works. It's not 100%, but it's pretty good.


Working with a locums CRNA today, and observed that she fills her endotracheal cuffs with lidocaine; Claims it promotes smoother extubation w/ less cough. New to me.

Found this:
http://www.anesthesia-analgesia.org/content/94/1/227.full

Anybody do this? Many of my partners and CRNA's use LTA's. I didn't use them very much in training and don't make it a regular practice myself.

Concerns with this practice? (filling cuff w/ lido)

Always willing to put a new technique under my belt for that special situation, but was wondering what others thought.
 

dhb

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There are at least 5-10 papers on lidocaine in the cuff on pubmed, and each uses a different conc/volume of lidocaine and NaHCO3. It works. It's not 100%, but it's pretty good.
Can you show us this data?
 

pgg

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Filling endotracheal tube cuffs with a liquid instead of air will most likely increase the pressure on the tracheal mucosa for little or no added benefit.
These cuffs are meant to be high volume low pressure cuffs and if we fill them with anything other than air we are most likely altering that desirable characteristic.
I don't think so. Putting a liquid in the cuff instead of a gas doesn't automatically elevate mucosal pressure unless you really fill it up (which you can do with air, too). If the pilot balloon is still soft (squishy-grape-like) or if you actually measure the pressure (which of course we know really never gets done outside an ICU), then the pressure in the cuff itself is still appropriate.

Cuffs are also routinely filled with saline for air transport patients, so putting a liquid in the cuff isn't a totally crazy, out there proposition.
 

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agree, I just don't think it's a big deal unless you put a whole bunch of liquid in there

I don't think so. Putting a liquid in the cuff instead of a gas doesn't automatically elevate mucosal pressure unless you really fill it up (which you can do with air, too). If the pilot balloon is still soft (squishy-grape-like) or if you actually measure the pressure (which of course we know really never gets done outside an ICU), then the pressure in the cuff itself is still appropriate.

Cuffs are also routinely filled with saline for air transport patients, so putting a liquid in the cuff isn't a totally crazy, out there proposition.
 

Planktonmd

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I don't think so. Putting a liquid in the cuff instead of a gas doesn't automatically elevate mucosal pressure unless you really fill it up (which you can do with air, too). If the pilot balloon is still soft (squishy-grape-like) or if you actually measure the pressure (which of course we know really never gets done outside an ICU), then the pressure in the cuff itself is still appropriate.

Cuffs are also routinely filled with saline for air transport patients, so putting a liquid in the cuff isn't a totally crazy, out there proposition.
Air is more compliant than fluids and it allows a better distribution of pressure over the surface which is why we don't fill car tires with water for example.
I don't have data supporting this in ETT tubes, but there is no data showing that filling the cuff with liquid compared to gas will produce the same pattern of pressure distribution and the same safety either.
If you are using Nitrous oxide though then theoretically filling the cuff with liquid might lower the chances of cuff expansion.
I am not saying that it is crazy or unheard of to fill cuffs with liquid, I am just comparing it's presumed benefit to it's potential risk.
 

pgg

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Air is more compliant than fluids and it allows a better distribution of pressure over the surface which is why we don't fill car tires with water for example.
You probably didn't want to get off into a physics discussion :) but the above, while (more or less) technically correct is irrelevant.

While greater compressibility or lesser viscosity might make a difference if the air/fluid was moving in and out of the cuff, once it's in there, the pressure is what it is. Tires move and the compressibility of air helps absorb random bumps and shocks better than solid rubber or water would; a cuff, once inflated with whatever substance, just sits there. If you fill a cuff to a pressure of 18, it's not going to increase to 32 later and inflict ischemic injury on the trachea. It's going to be 18.

Furthermore, at physiologically relevant (ie, low) pressures, the compressibility of air vs the non-compressibility of a liquid isn't going to make any difference. Air is compressible, yes, but it's not going to compress to the point that the pressure in the adjacent tissue is less than the pressure in the cuff; physics doesn't work that way.

As you know, the fact that the cuff is designed to be a "high volume, low pressure" device doesn't make it impossible for you to overinflate it and cause ischemic injury. It simply means that it's designed to effectively occlude the trachea at a lower pressure than a low volume cuff.

Provided you fill the cuff to an appropriate pressure, there's no mechanism that I can see that would make using a liquid raise the risk of ischemic injury. There may be good reasons to not put a liquid in a cuff but fear of causing tracheal ischemia isn't one of them.
 

Jay K

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Nice discussion.

I probably will continue my non-use of LTA's - seems to be a waste of money and a good way of generating medical waste. As an aside, I've been trying to limit my production of medical waste per case.

Filling the endotracheal cuff with a small mixture of alkalinized lido in lieu of an LTA, for the rare circumstance, will be another thing I may add to my bag of tricks. However, I wonder if it's really worth breaking open a 50mL vial of sodium bicarb just to mix w/ some lido to "maybe" smooth out an extubation. I really haven't seen a real need for this yet (in my practice), so... we'll see.
 

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As you know, the fact that the cuff is designed to be a "high volume, low pressure" device doesn't make it impossible for you to overinflate it and cause ischemic injury. It simply means that it's designed to effectively occlude the trachea at a lower pressure than a low volume cuff.

Provided you fill the cuff to an appropriate pressure, there's no mechanism that I can see that would make using a liquid raise the risk of ischemic injury. There may be good reasons to not put a liquid in a cuff but fear of causing tracheal ischemia isn't one of them.
The liquid in the cuff will not distribute the pressure equally over the contact surface which means there will be points that will receive more pressure than others.
The liquid also will follow gravity more than gas and exercise more pressure in the lowest part of the cuff.
You really have no evidence supporting all these assumptions that liquid is as safe as air in the cuff from a mucosal ischemia point of view do you?
And let me bring this little point up too:
Since most of us use the feel of the balloon between the fingers to estimate the amount of pressure in the cuff can you tell me that you are able to estimate the pressure correctly in the same manner if it was filled with liquid?
As I said, it's not a novel or unheard of thing to use liquid but in my opinion tracheal ischemia is one of the main problems here even if you don't agree.
 

pgg

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The liquid in the cuff will not distribute the pressure equally over the contact surface which means there will be points that will receive more pressure than others.
The liquid also will follow gravity more than gas and exercise more pressure in the lowest part of the cuff.
This is a mixture of nonsense and irrelevant statements with no basis in physics. If the pilot balloon is soft, then the fluid pressure at any point in the cuff can not be any higher than what a vertical column of fluid from the pilot balloon to the cuff would create. In a supine patient this places the absolute upper limit of the pressure at the lowest point in the cuff around 10-15 cm. In reality, it's going to be substantially less than that because the pilot balloon is sealed; there's no open column of air above the saline. This is basic physics. These pressures are unquestionably, indisputably safe.

You really have no evidence supporting all these assumptions that liquid is as safe as air in the cuff from a mucosal ischemia point of view do you?
The only evidence I really need can be found in any high school physics textbook. (Well, maybe not one from Kansas, where they "teach the controversy" ...)

I don't know what to tell you. If you're the sort of person who needs a double blind, randomized, placebo controlled trial to convince you that parachutes decrease mortality for people who jump out of airplanes ... none of this academic discussion is worthwhile, because you're going to withhold judgment ad infinitum.

And let me bring this little point up too:
Since most of us use the feel of the balloon between the fingers to estimate the amount of pressure in the cuff can you tell me that you are able to estimate the pressure correctly in the same manner if it was filled with liquid?
Yes.

As I said, it's not a novel or unheard of thing to use liquid but in my opinion tracheal ischemia is one of the main problems here even if you don't agree.
I disagree. Your opinion is wrong; your concerns unfounded. :)

It's not bad to be conservative and cautious, but we're anesthesiologists, people with 12+ years of rigorous postsecondary education. It's OK for us to think about these things and reach conclusions based on well-understood facts and principles.

It's not often that immutable laws of physics so clearly illustrate the answer, but this is one of those cases.
 

Planktonmd

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I actually think that you have never really filled a cuff with fluid and tried to feel what the balloon feels like.
Why don't you go do anesthesia for more than 3 months, pass your boards then come back and have a discussion?
So far you failed to introduce any evidence that supports your theoretical hypothesis and all you have is your unfounded opinion based on your almost non existing clinical experience.
I hate to say it but you actually are becoming increasingly another coprolalia.
You imagine things and then you assume that what's in your imagination is reality and expect the world to agree with you!
Tomorrow fill a cuff with a liquid, squeeze the balloon and tell me what it feels like, mister junior moderator!



This is a mixture of nonsense and irrelevant statements with no basis in physics. If the pilot balloon is soft, then the fluid pressure at any point in the cuff can not be any higher than what a vertical column of fluid from the pilot balloon to the cuff would create. In a supine patient this places the absolute upper limit of the pressure at the lowest point in the cuff around 10-15 cm. In reality, it's going to be substantially less than that because the pilot balloon is sealed; there's no open column of air above the saline. This is basic physics. These pressures are unquestionably, indisputably safe.



The only evidence I really need can be found in any high school physics textbook. (Well, maybe not one from Kansas, where they "teach the controversy" ...)

I don't know what to tell you. If you're the sort of person who needs a double blind, randomized, placebo controlled trial to convince you that parachutes decrease mortality for people who jump out of airplanes ... none of this academic discussion is worthwhile, because you're going to withhold judgment ad infinitum.



Yes.



I disagree. Your opinion is wrong; your concerns unfounded. :)

It's not bad to be conservative and cautious, but we're anesthesiologists, people with 12+ years of rigorous postsecondary education. It's OK for us to think about these things and reach conclusions based on well-understood facts and principles.

It's not often that immutable laws of physics so clearly illustrate the answer, but this is one of those cases.
 

Planktonmd

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Actually this is for every one other than PGG (because pgg already knows everything), try to fill the cuff with whatever volume you usually use to fill it but instead use a liquid and see if you are actually able to tell how inflated it is by feeling the balloon between your fingers..
 

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The liquid in the cuff will not distribute the pressure equally over the contact surface which means there will be points that will receive more pressure than others.
The liquid also will follow gravity more than gas and exercise more pressure in the lowest part of the cuff.

You really have no evidence supporting all these assumptions that liquid is as safe as air in the cuff from a mucosal ischemia point of view do you?
And let me bring this little point up too:
Since most of us use the feel of the balloon between the fingers to estimate the amount of pressure in the cuff can you tell me that you are able to estimate the pressure correctly in the same manner if it was filled with liquid?
As I said, it's not a novel or unheard of thing to use liquid but in my opinion tracheal ischemia is one of the main problems here even if you don't agree.
Can you elaborate on this because I'm not really understanding why this may be true?
 

Planktonmd

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Can you elaborate on this because I'm not really understanding why this may be true?
Sure,
These cuffs if you look at them are like a plastic bag, they are designed to be inflated with gas that will distribute equally within their cavity and as a result distribute the pressure equally.
If you fill them with liquid that liquid will just collect in the lower portion of the cuff (exactly like putting a liquid in a plastic bag) and it will create more pressure there than anywhere else.
Whether this is clinically relevant or not we don't know because no one has studied mucosal perfusion when a cuff is filled with a liquid.
 

Jay K

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Sure,
These cuffs if you look at them are like a plastic bag, they are designed to be inflated with gas that will distribute equally within their cavity and as a result distribute the pressure equally.
If you fill them with liquid that liquid will just collect in the lower portion of the cuff (exactly like putting a liquid in a plastic bag) and it will create more pressure there than anywhere else.
Whether this is clinically relevant or not we don't know because no one has studied mucosal perfusion when a cuff is filled with a liquid.
Nice illustration and very good point.
 

fakin' the funk

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I probably will continue my non-use of LTA's - seems to be a waste of money and a good way of generating medical waste. As an aside, I've been trying to limit my production of medical waste per case.
An aside worthy of a thread hijack. Do tell.
 

pgg

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Ah, more argument from authority. "I'm older than you, have been an attending longer, therefore you are automatically wrong." You're treating a simple technique that has been done for many years in many circumstances as if it's some risky thing to do. You usually have reasonable things to say, but this is just ... out there.

I actually think that you have never really filled a cuff with fluid and tried to feel what the balloon feels like.
You're incorrect; I used to do it routinely for air transport patients between 2004 and 2006.

Why don't you go do anesthesia for more than 3 months, pass your boards then come back and have a discussion?
Why don't you address the basic physics I pointed out to you instead of retreating into your usual "I know better, because" arguments?

So far you failed to introduce any evidence that supports your theoretical hypothesis and all you have is your unfounded opinion based on your almost non existing clinical experience.
Here's a list of references for you. Pick one.

Discussing things like this with you reminds me of the rare attending who earnestly argued about silly dogmatic topics. There is nothing inherently unsafe or risky about filling an ETT cuff with saline. If you're uncomfortable with it, fine, I'm not trying to make you do anything.

I hate to say it but you actually are becoming increasingly another coprolalia.
It really is unfortunate that out of him, militarymd, and you, you're the one who chose to stick around.

They had their issues too :) but at least it was clear they were thinking about what they believed.

You imagine things and then you assume that what's in your imagination is reality and expect the world to agree with you!
What I expect, and what you consistently fail to do, is actually address others' arguments. Case in point: post #20 in this thread, in which you restate what you wrote in #15, and which I clearly refuted in #16. Your response here is a mixture of
  • accusing me of lying about ever putting saline in a cuff
  • claiming that your authority of age and experience alone makes you correct
  • multiple snide comments
Tomorrow fill a cuff with a liquid, squeeze the balloon and tell me what it feels like, mister junior moderator!
I've done it many times. If the pilot balloon is soft, the pressure in the cuff is low. Yes, it feels a little different. Yes, saline is more viscous than air. Yes, it takes an extra second or two for pilot/cuff pressures to equilibrate. But they do equilibrate, and you can estimate cuff pressure the same way you can with air.


Planktonmd said:
Whether this is clinically relevant or not we don't know because no one has studied mucosal perfusion when a cuff is filled with a liquid.
That's like saying we'll never know if taping eyeballs shut reduces the incidence of corneal abrasians because no one has ever done a blinded fluorescein study on postop patients.

I can't believe I've spent this much time debating YOU on such a trivial topic. I'm not going to go on repeating myself. Believe what you want.
 

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Dear PGG,
It is unfortunate that I am unable to communicate with you as an adult or as a physician colleague because you have already made your mind and decided that you know all that there is to know.
I am also sorry that your buddies MMD and copro have left you but don't worry they will be back.
When I tell you that you lack experience it is not to insult you but it is to bring you back to planet earth before you become another copro.
If the moderators of SDN feel that my presence here is regrettable as you stated then I will be glad to accommodate your wishes and stop participating here.
If that's the case and SDN feels that I am not wanted here all I can do is withdraw peacefully.
Please consult with your more experienced mods and admins and let me know.
 

pgg

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I apologize for my comment about your presence being unfortunate. I find our discussions frustrating at times but they're worth having. If nothing else they make me think and justify my positions. It's good to have experienced people around here. Even if you drive me crazy sometimes. :)
 

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Sure,
These cuffs if you look at them are like a plastic bag, they are designed to be inflated with gas that will distribute equally within their cavity and as a result distribute the pressure equally.
If you fill them with liquid that liquid will just collect in the lower portion of the cuff (exactly like putting a liquid in a plastic bag) and it will create more pressure there than anywhere else.
Whether this is clinically relevant or not we don't know because no one has studied mucosal perfusion when a cuff is filled with a liquid.
you are assuming no external compression but once you inflate this cuff in the trachea then the pressure is conducted throughout the container, right?

ive done this for neuro cases, im unimpressed, but it might help people who havent really planned for wakeup or in situations where you might need the patient to be REALLY awake but they have a fresh thyroid or somesuch (difficult airway blah blah). anecdotally ive found that bicarb added to this works a lot better
 

Planktonmd

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you are assuming no external compression but once you inflate this cuff in the trachea then the pressure is conducted throughout the container, right?
No, I actually think that the liquid would still pool in the lower part of the cuff unless you use a much bigger volume that will actually fill the whole cuff (remember these cuffs have huge capacity).
On the other hand air will spread equally throughout the cuff at any volume.
 

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that doesnt, matter, as pressure will equalize and the fluid will be driven towards the lower pressure side until equilibration. there is an external force necessary to produce tracheal occlusion and this creates an internal driving force.

i mean if the pressure in the bottom of the cuff is 19 and the pressure in the top of the cuff is 17 then fluid will shift from the bottom to the top to equalize it (ill give you a little leeway for gravity but not that important here) - am i missing something?
 

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Air is more compliant than fluids and it allows a better distribution of pressure over the surface which is why we don't fill car tires with water for example.

If you are using Nitrous oxide though then theoretically filling the cuff with liquid might lower the chances of cuff expansion.
Well, car tires filled with water would weigh several hundred pounds collectively with a huge rotational inertia. Not sure that the distribution of pressure would be any different, though, think water bed.

Also, if the cuff is filled with a liquid and you are using nitrous, I would think you would actually be at high risk of over expansion because you are effectively reducing the volume available in the cuff for the volume to expand before raising the pressure significantly. Some nitrous will dissolve in the fluid in the cuff, but it will exert a signifant outward pressure by a relatively small volume diffusing into the gas filled portion of the balloon. think of it as the liquid won't compress to make room for more nitrous, whereas if there were no liquid, of course the gas in the cuff makes room for more as it compresses...

Just my thoughts,
BNE
 

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The liquid in the cuff will not distribute the pressure equally over the contact surface which means there will be points that will receive more pressure than others.
Plank, I agree that we should be concerned about tracheal ischemia whether it is liquid or gas, but the above statement isn't true. The pressure in the liquid will be distributed evenly over the contact surface. The pressure inside the balloon is directed "normal" to the balloon surface in all directions.

The liquid also will follow gravity more than gas and exercise more pressure in the lowest part of the cuff.
Well, this is true, but we're talking 1-2 cm of H20 (by definition) difference since the width/height of the cuff is about 1-2 cm.

BNE
 
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This is a mixture of nonsense and irrelevant statements with no basis in physics. If the pilot balloon is soft, then the fluid pressure at any point in the cuff can not be any higher than what a vertical column of fluid from the pilot balloon to the cuff would create. In a supine patient this places the absolute upper limit of the pressure at the lowest point in the cuff around 10-15 cm.
Actually, if I understand you correctly, the pressure would be 10-15cm H2O PLUS the pressure measured in the balloon, as a maximum. Pilot balloons can still feel soft at 40cm H20 (like our breathing bag), so this means the pressure could be 55cmH20 which is approx 40 mmHg which is enough to cause ischemia IMHO.

BNE.
 

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This is only true if the cuff contained a mixture of air and liquid.
If the cuff only contained a liquid then the increase in volume will be negligible since nitrous has a very poor solubility in water.



Also, if the cuff is filled with a liquid and you are using nitrous, I would think you would actually be at high risk of over expansion because you are effectively reducing the volume available in the cuff for the volume to expand before raising the pressure significantly. Some nitrous will dissolve in the fluid in the cuff, but it will exert a signifant outward pressure by a relatively small volume diffusing into the gas filled portion of the balloon. think of it as the liquid won't compress to make room for more nitrous, whereas if there were no liquid, of course the gas in the cuff makes room for more as it compresses...

Just my thoughts,
BNE
 

Planktonmd

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To achieve tracheal occlusion using a fluid in the cuff you will need more volume because if you use the same volume, lets say 5cc, this will simply sit in the bottom of the cuff, then you will need to increase the volume so it fills the whole cuff and this will produce more pressure.
Also, your balloon will not have a continous cloumn of fluid to the cuff cavity and it will be worthless in estimating the real pressure inside the cuff.
Also, the feel of a balloon full of fluid is completely different than the feel of a balloon full of air.
So, in conclusion, You can fill the cuff with whatever you want but if you are not using air then you are altering the proprties of the cuff, the function of the balloon and possibly altering the safety profile of the tube.
Whaether this is clinically relevant or not remains to be determined when someone studies it.



that doesnt, matter, as pressure will equalize and the fluid will be driven towards the lower pressure side until equilibration. there is an external force necessary to produce tracheal occlusion and this creates an internal driving force.

i mean if the pressure in the bottom of the cuff is 19 and the pressure in the top of the cuff is 17 then fluid will shift from the bottom to the top to equalize it (ill give you a little leeway for gravity but not that important here) - am i missing something?
 

IlDestriero

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To achieve tracheal occlusion using a fluid in the cuff you will need more volume because if you use the same volume, lets say 5cc, this will simply sit in the bottom of the cuff, then you will need to increase the volume so it fills the whole cuff and this will produce more pressure.
Also, your balloon will not have a continous cloumn of fluid to the cuff cavity and it will be worthless in estimating the real pressure inside the cuff.
Also, the feel of a balloon full of fluid is completely different than the feel of a balloon full of air.
So, in conclusion, You can fill the cuff with whatever you want but if you are not using air then you are altering the proprties of the cuff, the function of the balloon and possibly altering the safety profile of the tube.
Whaether this is clinically relevant or not remains to be determined when someone studies it.
Why can't you just check for a leak. If there's a leak at a reasonable inspiratory pressure, I doubt that you're at any risk for pressure induced mucosal damage. The role of gravity on a few grams of water is dubious.
The cuffed tracheostomy tubes that we use specify that sterile water be used in the cuff. They work with air as well, but they recommend water. Surely the manufacturer must have some research supporting its safety. That is if anyone is actually interested in looking at research that may be available for the safety of using a liquid in a cuff. Colored liquid in a cuff during airway surgery is also not a new concept. I don't seem to recall a lot of case reports of mucosal damage below the site of surgery in those cases.
 

Planktonmd

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I think this discussion has gone way beyond it's merit.
I did not say that putting a liquid in the cuff is a "new concept", I actually do it reguralrly for airway sugerey as you mentioned.
All I am saying is that I have doubts about it's safety and maybe I am being paranoid here.
It's one of these things you could say "I just don't like doing it this way".
And after doing this business for a number of years you are entitled to develop likes and dislikes.

Why can't you just check for a leak. If there's a leak at a reasonable inspiratory pressure, I doubt that you're at any risk for pressure induced mucosal damage. The role of gravity on a few grams of water is dubious.
The cuffed tracheostomy tubes that we use specify that sterile water be used in the cuff. They work with air as well, but they recommend water. Surely the manufacturer must have some research supporting its safety. That is if anyone is actually interested in looking at research that may be available for the safety of using a liquid in a cuff. Colored liquid in a cuff during airway surgery is also not a new concept. I don't seem to recall a lot of case reports of mucosal damage below the site of surgery in those cases.