Use C-Flex with Breeze?

eugene · Post by **eugene** » Sat Mar 19, 2005 2:47 am

I read in the REMstar Auto C-Felx instructions that it is advisable not to use devices (masks) with narrow tubes, such as the Breeze.

Has anyone done this? Was there a problem? I am thinking of buying this combination.

Thanks

wading thru the muck! · Post by **wading thru the muck!** » Sat Mar 19, 2005 7:27 am

santacruz,

I've used that combination and have gotten similar good results to any other interface.

rested gal · Post by **rested gal** » Sat Mar 19, 2005 3:59 pm

Hi santacruz -

Like Wader, I've had no problem at all using the Breeze, Swift, and Aura with my Respironics REMstar Auto with C-flex.

Hugh Jass · Post by **Hugh Jass** » Mon Mar 21, 2005 6:39 am

I use this combination without any problems.

Frankly, I can't understand why a company would claim such a thing.

10 CM of pressure is 10 CM of pressure, irregardless of the size of tubing in the circuit.

Mikesus · Post by **Mikesus** » Mon Mar 21, 2005 8:55 am

It isn't the pressure that they are worried about. It is the detection of events. Narrow tubing might affect it. From what has been said here, it doesn't appear to tho. Prolly a PYA thing.

rested gal · Post by **rested gal** » Mon Mar 21, 2005 9:34 am

As Mike says... it's about detection of events.

I think the companies' concern is not with the air going into the patient, but more with the air coming out. Apparently the characteristics of air flow are changed in a narrower tube. If the autopap is designed to "read" air flow coming from a patient as being from a standard size main air hose, but then sees a different kind of air flow due to the narrow connector tube changing not the pressure itself but the way the air flow behaves, the machine might misinterpret what's happening with the patient's breathing.

I've heard the narrow vs regular hose air flow changes described as being similar to what happens when you put your thumb partially over the end of a garden hose. Narrowing the end of a water hose with your thumb will create a completely different flow pattern - a different spray pattern. The Venturi Effect. I had never heard that term (or the garden hose/thumb description of it) until last year, in an explanation by SWS.

Air or water...the "flow" principle is essentially the same. Make the tube/hose more narrow at some point, and the air (or water) flow pattern - the characteristics of the flow - will be changed even though the pressure remains the same. Correctly sensing the air flow characteristics from the patient are important to how an autopap understands what's happening and decides what to do.

I may have have stated a lot of that wrong though. I'm one who mixes up leaks with litres, remember!

It's a pretty drastic thing for manufacturers to specifically not recommend one of their own masks with their own autopap, as Respironics did when they came out with their ComfortLite nasal pillows interface, nor did they recommend it for use with any autopap. However, several message board "lab rats" went right ahead anyway and did report using the ComfortLite with their Respironics autos just fine. People have also used the Breeze (narrow connector tube, too) successfully with Respironics autos as well as with other makers' autos for years.

On the other hand, Puritan Bennett/Malinkrodt, the makers of the Breeze, designed the 420E autopap and the narrow diameter connector hose Breeze for each other. Perhaps the extra air sensor line that runs up through the main air hose of all 420E's makes the difference? The extra sensor tube begins reading the airflow where the narrow diameter tube and the main air hose are connected. I've always wondered how much swirling of air flow is happening right there at the juncture though.

I suppose there are a few people whose breathing pattern coupled with air flow characteristics changing between a narrow diameter hose and a bigger diameter main air hose would be a problem for some autopaps to interpret. If the autopap figures it wrong, then the autopap might choose to take the wrong action for that patient. Might raise the pressure when not needed, or vice versa.

In this day and age of big liability issues, I guess the machine/mask manufacturers take an ultra conservative CYA stance (as Mike said) just in case a particular patient/mask/autopap combo doesn't gee and haw well together due to the machine misinterpreting the air flow characteristics that will change on their way through two different sizes of tube - narrow connector tube and bigger main air hose.

However, if one goes by what experienced users on message boards report - especially those who have the software to take a look at how their autopaps are behaving - most people can use the narrow diameter connector tube masks (Breeze, Swift, Aura, Nasal Aire II, etc.) with good treatment results from any autopap. I've used several of those masks with several different autopaps - no problem.

Mikesus · Post by **Mikesus** » Mon Mar 21, 2005 11:45 am

The Venturi effect is the speeding up of air, or another fluid, as it passes through a constriction.

If the machine is sensing volumetric changes (changes in the amount of air being moved) then the venturi effect would not bother the machine as the venturi effect changes the speed, not the volume. Unless, the constriction is such that it blocks the flow entirely.

From my understanding tho, the auto machines sense flow rate. But all things being equal, the constriction should increase all air flow and the auto's should be able to still sense it.