NC or NRB when suction is needed?

mycrofft

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Robb, thanks for the quick citations. They got in before that second long entry I made, it was not a response to your two replies. I'm studying them.

I'll get back when I have my reply from Hudson.
 
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Handsome Robb

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mycrofft said:
Robb, thanks for the quick citations. They got in before that second long entry I made, it was not a response to your two replies. I'm studying them.

I'll get back when I have my reply from Hudson.
Click to expand...

gotcha. Sorry I'm a touch irritable today.
 
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Underoath87

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mycrofft said:
I have head of these also, don't they totally occlude the nares? Wonder if the gas hisses into the oropahrynx if you open your mouth with it on? (I've seen pictures of one which also has a small prong which extends over the lips! Never seen in person though).
Click to expand...

The prongs did practically occlude the nares.


As Brandon O mentioned, it can create positive pressure, so I assume the RT set it up because the patient wouldn't tolerate a c-pap or bi-pap.

I think some of the confusion in this debate lies in the different types of NC's.
Robb, you mentioned NC's being used at 15L for some procedures. But those are likely high flow cannulas which are designed to flow 15 L (they have larger diameter prongs). Mycroft is referring to a standard cannula, which is what the OP was using.
 
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Underoath87 said:
The prongs did practically occlude the nares.


As Brandon O mentioned, it can create positive pressure, so I assume the RT set it up because the patient wouldn't tolerate a c-pap or bi-pap.

I think some of the confusion in this debate lies in the different types of NC's.
Robb, you mentioned NC's being used at 15L for some procedures. But those are likely high flow cannulas which are designed to flow 15 L (they have larger diameter prongs). Mycroft is referring to a standard cannula, which is what the OP was using.
Click to expand...

No, they're not, they're standard cannulas in emergent airway situations. Our flight crews do it with standard cannulas and get good results, anyone I intubate gets it as well respiratory or cardiac arrest.

I can ask their clinical officer for the data but I'm not sure they'd give it to me. They QA each other.
 
mycrofft

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The citation about adding canulas to oxygen masks seemed to me to make it clear they were using standard cannulas, not special ones.

I am unable to find any studies comparing effective flow versus indicated flow in cannulas pushed beyond their rated LPM's.

Are these rates being measured by a Bourdon, Pitot, or other type gauge? Or using a regulator with dents ("clicks") in the flow meter knob which indicate arbitrarily what LPM is being issued but not actually being measured?

Bourdon style: can indicate increase in flow rate if there is an obstruction because it operates on the pressure in the curved measuring tube connected to the dial, like an aneroid sphyg. "Obstruction" in this case could be turbulence in the tubing or the nasopharynx or elsewhere.

sotgsrgO2_flwgg_us_l.jpg


Pitot style indicates true flow if it is close to upright and interior of the vertical chamber is dry.

X2604-F-15.png


Precalibrated fixed-flow style : works only if the designated delivery style is used (cannula, regular mask, non-rebreather mask, rescue mask with headband and O2 port) because it does not truly measure flow rate.

o2-regulator-dial-reg-168708d.jpg


Bourdon and fixed-flow regulators might indicate a higher flow rate when the actual flow rate at the patient was the same or only very slightly raised because of intracannular turbulence (or other obstructions) .

Like taking a police whistle and hooking it up to an air compressor and expecting to get a siren but all you get is a crummy dog whistle, if anything.

I'm going to try to find more about high flow cannulas.
 
mycrofft

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mycrofft

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OK enough for tonight..High flow NC

Here are two styles of increased O2 cannulas, the "mustache reservoir", and the "pendant reservoir". Each purportedly accumulates oxygen during non-inspiratory periods then the next inhalation claims it.
e6b6b466d5.jpg

==============
Mosby's RESPIRATORY CARE EQUIPMENT (J. M. Cairo, Elsevier Books), copyright 2014, pg 93, para 4:
AND I QUOTE:
"Oxygen flows higher than 6 L/min delivered with a traditional nasal cannula system do not produce a significantly higher F1 O2…". (red accents courtesy of mycrofft)
==============
 
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Melclin

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At SMACCgold, Rich Levitan had some interesting things to say about the apparent superiority of nasal cannulae over face masks for many purposes (not just the apneic oxygenation during intubation for which he is well known).

Personally, I hate face masks. I always have and this trend towards NC is music to my ears. Hard to talk to the patient and despite local dogma, they don't seem to make pts feel any better purely by virtue of looking like a meaningful intervention. In my own practice I raise flow rate via NC up to a limit of 6-10, depending on transport time and effect/adverse reactions. I've never really had any problems. Levitan seemed to suggest that exceeding these traditional limits in the short term was entirely appropriate, safe and efficacious. Nothing super definitive, just a compelling argument with few bits of low-LOE type papers from memory.. Talked a bit about rebreathing CO2 with most masks despite efforts to avoid this (one way valves, increased flow rates etc) and it leading to discomfort and potentially worse outcomes. Do catch his lecture if they release it.
 
mycrofft

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[YOUTUBE]https://www.youtube.com/watch?v=-2wXE56N8kE[/YOUTUBE]
Melclin said:
At SMACCgold, Rich Levitan had some interesting things to say about the apparent superiority of nasal cannulae over face masks for many purposes (not just the apneic oxygenation during intubation for which he is well known).

Personally, I hate face masks. I always have and this trend towards NC is music to my ears. Hard to talk to the patient and despite local dogma, they don't seem to make pts feel any better purely by virtue of looking like a meaningful intervention. In my own practice I raise flow rate via NC up to a limit of 6-10, depending on transport time and effect/adverse reactions. I've never really had any problems. Levitan seemed to suggest that exceeding these traditional limits in the short term was entirely appropriate, safe and efficacious. Nothing super definitive, just a compelling argument with few bits of low-LOE type papers from memory.. Talked a bit about rebreathing CO2 with most masks despite efforts to avoid this (one way valves, increased flow rates etc) and it leading to discomfort and potentially worse outcomes. Do catch his lecture if they release it.
Click to expand...

Great presentation. Doesn't it also stand to reason that if you could see the cords, the pt can breathe better even if they are just being positioned for respiratory comfort by first aid or BLS?


https://www.youtube.com/watch?v=-2wXE56N8kE
 
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Melclin

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Yup it was.

The link you posted isn't the same one (but I don't think it was supposed to be :)) but contained a lot of the same anatomy.

I wish I had been able to jot down a few of his references. But they all changed slides so quickly. I'm sure it'll be up somewhere soon.
 
Brandon O

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mycrofft said:
Mosby's RESPIRATORY CARE EQUIPMENT (J. M. Cairo, Elsevier Books), copyright 2014, pg 93, para 4:
AND I QUOTE:
"Oxygen flows higher than 6 L/min delivered with a traditional nasal cannula system do not produce a significantly higher F1 O2…". (red accents courtesy of mycrofft)
==============
Click to expand...

That'll be the first real source I've seen for that claim. Is it cited in the text?

Usually the explanation for not exceeding a flow of 6-8 is due to discomfort and drying, which is certainly valid, but somewhat beside the point for short-term emergent situations. I have HEARD the idea that a standard cannula somehow cannot "handle" higher flow rates, but never with any serious attempts at justification, just from the same sorts of people who quote their instructors with gems like fluid loading in sepsis is to "dilute the poison."

If you like your flowmeter demo, just try it; plug a cannula into the wall O2 next time you're at work and crank it up. You can see how it easily reaches 15 liters. (Maybe you have to turn the knob a little farther than you would with, say, a NRB... if the tubing is narrower [never really compared them] there could be additional resistance -- Poiseuille and all that -- but regardless, there's pressure to spare.)
 
mycrofft

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I use the words "AND I QUOTE", as I explained, because one mod felt that simply using quotation marks and listing a citation wasn't enough to indicate verbatim from a source. SO, yes, it is word for word, page 93, paragraph four.

The Mosby textbook is stating (not citing a study, ?? source) physiological findings which indicate the extra flow is not physiologically advantageous. That seems to trump any physical increase in delivery.

QUOTE: "...do not produce a significantly higher F1 O2".

I was thinking last night about how one could use a tank of water, a one liter plastic bottle, a stopwatch*, a gas cylinder with a pitot flow meter, and a nasal cannula to test it like MYTHBUSTERS. But I'm retired, I'll have to sneak into the local ER and try it out, and make a video for DE Medic. ;)

If you're local to Central Calif I could rendezvous with your truck and do it sometime, with about a day notice to empty the bottle and find a big enough bucket...:ph34r:

*"Stopwatch"…yeah, I know "what's that?", so I'm a codger..:sad:
 
mycrofft

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VFlutter

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Underoath87 said:
This is what they make high-flow cannulas for (up to 15 L/min).

I once picked up an ICU pt going to a hospice house that was on a special 60 L/min cannula. The thing had huge blue prongs and required a special air pump (we switched her to a NRB for the transport, if I recall).
Click to expand...

chriscemt said:
Does something like that actually work? And, really, for what need would any patient have more than 100% O2?
Click to expand...

We use "Salter" Cannulas for flows up to 15 L/min. They look like standard Nasal Cannulas but are green and have larger diameter tubing. They can provide ~90% Fi02.
41fKeORzyeL._SY300_.jpg


HFNC or HHFNC is (Heated/humidified) High flow nasal cannula looks more like a Nasal pillow CPAP than a NC. It requires a humidifier and control box. They can deliver flow rates up to 60 L/min and a Peep of 1.

Both work great. We use Salters much more than HFNC. But HFNC is great for patients who will not tolerate a CPAP/BiPAP mask. Many patients do better on a salters then they would with a Venti mask.


HFNC-overview2.jpg




I think a Salter NC @ 15 would be great for preoxygenation or peri-intubation.
 
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mycrofft

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ThadeusJ

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The theory behind nasal cannula being limited to 6 Lpm is based on the natural reservoir created by the naso-oropharynx. It is felt that as you increase litre flow, more and more of this cavity will be filled with oxygen, creating a bolus of oxygen. Beyond 6 Lpm, however, the cavity is filled and therefore you have reached optimal flow. The Salter product pictured above has much larger tubing and flows that minimize room air entrainment, thus providing higher oxygen concentrations.

The American Association of Respiratory Care states 1-6 Lpm, and offers many references, but doesn't explain why in the body of the text. Also, its a few years old, the so addition of high flow cannula aren't present.
http://services.aarc.org/source/DownloadDocument/Downloaddocs/08.07.1063.pdf
 
Brandon O

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ThadeusJ said:
The American Association of Respiratory Care states 1-6 Lpm, and offers many references, but doesn't explain why in the body of the text. Also, its a few years old, the so addition of high flow cannula aren't present.
http://services.aarc.org/source/DownloadDocument/Downloaddocs/08.07.1063.pdf
Click to expand...

The only paper they cite that bears upon this is this one, which unfortunately only investigates standard cannulas up to 6 LPM (they use the high-flow devices beyond that). They make the same claim about no increased flow about 6, but their citation is the same one that mycrofft quoted (Mosby).
 
mycrofft

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Brandon O said:
Doesn't seem to be anything addressing standard cannulas...
Click to expand...

Yeah. And the websites are sending me sales stuff not answering with URL's or even responsive emails.

I'll tap Dr. Levitan's website. They sell his lectures.
 
Brandon O

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Worst case we could probably write to the Mosby editors...
 
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