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Permalink Reply by Saz RPSGT on November 5, 2009 at 6:16pm

Hi Jan, I'll try to answer all of your questions. (I'll probably repeat some things you already know, but what the hey...)

The Auto M set for 8 and 17cmH20 is a machine that automatically changes pressure trying to find the best pressure for you. 8cmH20 being the lowest that it can go, and 17cmH20 being the highest. So, it starts at 8cmH20 and will stay there until it detects a shallowing of breathing. It could be Apnea, hypopnea, RERA...who knows....and the machine doesn't care, it just knows your breathing got funky and you pissed it off. So now it increases by 1.5cmH20. It keeps doing this fairly quickly (a couple of minutes) as it sees necessary. Once it gets to a pressure where you stop "getting funky breathing", it stops increasing the pressure. So it does not alter the pressure on each breath at all. That's the basics of an Auto M Series with Cflex (I'll explain cflex in a minute)

The BiPAP AUTO doesn't alter the pressure on each breath either. It functions in the same was as the CPAP Auto, but it is Titrating Inspiratory (IPAP) and Expiratory (EPAP) pressure. EPAP is increased until all Obstructive and Mixed Apneas are gone. Once gone, EPAP stays put. IPAP increases until Hypopneas and RERA (Respiratory event related arousals...subtle events) stop. 6 means the lowest EPAP is 6cmH20, 17 means 17cmH20 is the highest it can go for IPAP. It's typically a big no-no for EPAP to be within 4cmH20 of IPAP. So 12/8cmH20 is okay, but 12/10cmH20 is crazy stupid. (yes, that's the technical term.)

Cflex and BiFlex are completely different things. They are tools to help tolerate Positive Pressure. If you think of breathing as a wave, what Cflex and BiFlex work by making the air delivery feel more "smooth". It's hard and boring to describe the difference...but that's what I do. Cflex makes it feel like the air lets up upon exhalation. BiFlex does the same thing, but also makes the transition from EPAP to IPAP more gentle. Aflex is another term you may have heard of. Aflex is on CPAP machines and also makes the inhalation phase feel more gentle and "smooth."

You can test Cflex and BiFlex yourself by hitting the Flex button on your machine. 1 is the least and 3 is the most. Some people it makes a world of difference where others don't feel it at all.

Does that answer your question? I tried to explain the sleep jargon as best I could. I don't like to talk down to people. It's your disease, and you need to get familiar and comfortable with the jargon. Hopefully all that made some sense though.

Saz

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Permalink Reply by Jan on November 5, 2009 at 6:41pm

Thanks for taking so much time to explain this. If I understand correctly, the 6 number is titrating on exhalation and the 17 is titrating in inhalation? I think what is confusing me is that in the instance of the CPAP, it is titrating between two assigned numbers. It seems that in the case of the bi-pap, the "between number" is not stated.

With setting on the auto bipap of 6-17 is is accurate to say that my exhalation is titrating between 0 and 6 and my inhaling is titrating between 0 and 17.

Sorry if I am being dense....but want to really understand this.

Thanks, most appreciated.

Jan

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Permalink Reply by Saz RPSGT on November 5, 2009 at 9:11pm

No problem.

The 6 number is in reference to the lowest possible pressure (measured as cmH20) that the machine is going to generate to keep your upper airway open. The 17 is the highest amount of pressure that the machine is going to generate to keep your upper airway open.

With CPAP this means that it's trying to find one pressure that gets rid of all breathing events that cause you to wake up.

With BiPAP is more complicated. With a setting of Auto BiPAP 6-17, it means that the lower pressure and the upper pressure are both going to fall in the range of 6-17 in some combination. The lowest you would see is 10/6cmH20 (highest number, IPAP, is always first) once it has completed its automatic titration. The highest you would see is 17/13cmH20. It is unlikely, but possible, that you could end up with a pressure of 17/6cmH20.

So with BiPAP there is no in between pressure. It's best to think of them as pressures that have different goals in mind.

The lower pressure (with your range of 6cmH20-17cmH20) of 6 means that it starts at 6cmH20 and increases. Once you stop having the events where you completely stop breathing (obstructive apnea) it stops increasing. Let' say that it stopped occuring at 10cmH20. That gives you an EPAP of 10cmH20.

The higher pressure would start at 10cmH20 (since there is always a 4cmH20 spread at least with BiPAP) and increase until all breathing events that cause you to wake up are gone. This will occur at a pressure higher than when Obstructive Apneas stopped. Let's say that the rest of the breathing problems stopped at 16cmH20. This would mean that your best pressure for getting rid of all breathing problems (and keeping you asleep) is 16/10cmH20.

Let me know if that helps or not.

Saz

Jan said:

Thanks for taking so much time to explain this. If I understand correctly, the 6 number is titrating on exhalation and the 17 is titrating in inhalation? I think what is confusing me is that in the instance of the CPAP, it is titrating between two assigned numbers. It seems that in the case of the bi-pap, the "between number" is not stated.

With setting on the auto bipap of 6-17 is is accurate to say that my exhalation is titrating between 0 and 6 and my inhaling is titrating between 0 and 17.

Sorry if I am being dense....but want to really understand this.

Thanks, most appreciated.

Jan

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Permalink Reply by Jan on November 5, 2009 at 10:53pm

What I am really concerned about is when I was switched from CFlex settings of 8-17 to BiPap settings of 6-17, my AHI went from about 3 on cflex to about 7 on the bipap.

Any thoughts on that?

And thanks all for the great and detailed information. I really appreciate it.

Jan

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Permalink Reply by Jan on November 6, 2009 at 1:38am

Jeff, thanks for your responses. You are correct, it is an auto bipap and it was prescribed for comfort.

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Permalink Reply by Renee on November 6, 2009 at 4:54pm

Hello Saz ~

This is great ! -- And I think I understand it !

Thanks for putting the time and effort into this.

Thanks much,
Renee

Saz RPSGT said:

Hi Jan, I'll try to answer all of your questions. (I'll probably repeat some things you already know, but what the hey...)

The Auto M set for 8 and 17cmH20 is a machine that automatically changes pressure trying to find the best pressure for you. 8cmH20 being the lowest that it can go, and 17cmH20 being the highest. So, it starts at 8cmH20 and will stay there until it detects a shallowing of breathing. It could be Apnea, hypopnea, RERA...who knows....and the machine doesn't care, it just knows your breathing got funky and you pissed it off. So now it increases by 1.5cmH20. It keeps doing this fairly quickly (a couple of minutes) as it sees necessary. Once it gets to a pressure where you stop "getting funky breathing", it stops increasing the pressure. So it does not alter the pressure on each breath at all. That's the basics of an Auto M Series with Cflex (I'll explain cflex in a minute)

The BiPAP AUTO doesn't alter the pressure on each breath either. It functions in the same was as the CPAP Auto, but it is Titrating Inspiratory (IPAP) and Expiratory (EPAP) pressure. EPAP is increased until all Obstructive and Mixed Apneas are gone. Once gone, EPAP stays put. IPAP increases until Hypopneas and RERA (Respiratory event related arousals...subtle events) stop. 6 means the lowest EPAP is 6cmH20, 17 means 17cmH20 is the highest it can go for IPAP. It's typically a big no-no for EPAP to be within 4cmH20 of IPAP. So 12/8cmH20 is okay, but 12/10cmH20 is crazy stupid. (yes, that's the technical term.)

Cflex and BiFlex are completely different things. They are tools to help tolerate Positive Pressure. If you think of breathing as a wave, what Cflex and BiFlex work by making the air delivery feel more "smooth". It's hard and boring to describe the difference...but that's what I do. Cflex makes it feel like the air lets up upon exhalation. BiFlex does the same thing, but also makes the transition from EPAP to IPAP more gentle. Aflex is another term you may have heard of. Aflex is on CPAP machines and also makes the inhalation phase feel more gentle and "smooth."

You can test Cflex and BiFlex yourself by hitting the Flex button on your machine. 1 is the least and 3 is the most. Some people it makes a world of difference where others don't feel it at all.

Does that answer your question? I tried to explain the sleep jargon as best I could. I don't like to talk down to people. It's your disease, and you need to get familiar and comfortable with the jargon. Hopefully all that made some sense though.

Saz

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Permalink Reply by Jan on November 6, 2009 at 5:38pm

Jeff-- I really do appreciate all of the effort that you put into your response and trying to explain it. It is more or less clear, though I thought that Apneas happened when you breathe in (purposely using lay language so I dont confuse myself)...but based on what you said above about the titration, it appears that they happen on breathing out?

Thanks again...

Jan

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Permalink Reply by Jan on November 6, 2009 at 6:40pm

Well, you both have given me great info and insight. And I didn't know that the apneas happen during the period you described as sorta inbetween inhale and exhale. I simply misunderstood what was happening physically during this process. NOW, what Saz wrote yesterday makes much more sense to me...

Thank you Saz and Jeff!!!

Jan

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Permalink Reply by Renee on November 6, 2009 at 7:38pm

Hello Again Saz ~

This is such fantastic info. You have explained it so very well - and I can't believe but I can really understand it !

Thanks so much for all this,
Renee

Saz RPSGT said:

No problem.

The 6 number is in reference to the lowest possible pressure (measured as cmH20) that the machine is going to generate to keep your upper airway open. The 17 is the highest amount of pressure that the machine is going to generate to keep your upper airway open.

With CPAP this means that it's trying to find one pressure that gets rid of all breathing events that cause you to wake up.

With BiPAP is more complicated. With a setting of Auto BiPAP 6-17, it means that the lower pressure and the upper pressure are both going to fall in the range of 6-17 in some combination. The lowest you would see is 10/6cmH20 (highest number, IPAP, is always first) once it has completed its automatic titration. The highest you would see is 17/13cmH20. It is unlikely, but possible, that you could end up with a pressure of 17/6cmH20.

So with BiPAP there is no in between pressure. It's best to think of them as pressures that have different goals in mind.

The lower pressure (with your range of 6cmH20-17cmH20) of 6 means that it starts at 6cmH20 and increases. Once you stop having the events where you completely stop breathing (obstructive apnea) it stops increasing. Let' say that it stopped occuring at 10cmH20. That gives you an EPAP of 10cmH20.

The higher pressure would start at 10cmH20 (since there is always a 4cmH20 spread at least with BiPAP) and increase until all breathing events that cause you to wake up are gone. This will occur at a pressure higher than when Obstructive Apneas stopped. Let's say that the rest of the breathing problems stopped at 16cmH20. This would mean that your best pressure for getting rid of all breathing problems (and keeping you asleep) is 16/10cmH20.

Let me know if that helps or not.

Saz

Jan said:

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Permalink Reply by Renee on November 6, 2009 at 7:40pm

Hello Jeff,

Thanks for all this . . . quite interesting.

Best,
Renee

j n k said:

The way that machine works is that you program in how high the inhale pressure can go and how low the exhale pressure can go. The distance between the experienced inhale pressure and the experienced exhale pressure at any given moment will always be at least 2 cmH20. The maximum distance between experienced inhale and experienced exhale can be set, but it is usually left at the default of 8 cmH2O (out of sheer laziness, mostly, I believe). Biflex, by the way, is merely a comfort setting for smoothing out the transitions between the two pressures, so it doesn't really come into play in a discussion of therapy pressures.

So, Jan, lets take your setting of the range of 6-17. That means your machine starts out at 8/6 (inhale pressure is 8 cm and exhale pressure is 6 cm), since the minimum, nonadjustable pressure support setting on that machine is for a 2 cm difference. From there, your inhale pressure can range anywhere from 8 cm to 17 cm and your exhale pressure can range anywhere from 6 cm to 15 cm.-- always at least 2 cm apart but never more than 8 cm apart during the night (assuming max PS was left at the default setting).

I used a BiPAP Auto for a few weeks. Sweet machine. A little too loud compared to my ResMed VPAP Auto (ResMed's autobilevel, their version of the BiPAP Auto, if you will, only with fixed pressure support), but the Encore Pro software is major cool.

jeff

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Permalink Reply by Jan on November 6, 2009 at 8:11pm

I don't have a copy of the prescription handy (but will get it). Apropos a point earlier in the conversation, I believe the doctor said that he was setting the spread between the two at 4. Does that make sense?

I believe that the machine is on a rental paid by the insurance company-- however, I did pay some difference between what insurance would pay and the cost of the machine.

Thanks Jeff and Saz-- you have truly enlightened and taken a complicated topic and really explained it well.

Thanks
Jan

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