(Dreamstation) Flex algorithm is out of sync with my breathing

[skim]

Hi, CPAP newbie here after my first couple nights. Hoping some CPAP algorithm experts can help me out here.


The Dreamstation 1 with flex setting they said would adjust to my inhale/exhale, so I don't have to fight against pressure so much. The thing is the way I breathe doesn't jive with the algorithm. Usually, my sleep onset delay is like 3 minutes (confirmed in sleep study and all my at home apps), I do some really slow deep breaths and am off to sleep right away, probably because I'm so sleep deprived.

With this damn machine I spend hours being jolted awake right when I'm about to fall asleep because the machine keeps forcing air in when it thinks I should inhale, but I'm just pausing after exhale. Sometimes I find myself breathing out against full resistance. The algorithm has its own opinions about how I should be breathing, and if I follow that I feel very little resistance, but feel like I'm hyperventilating, and "rushing" my breath because I feel like any delay and I'm going to get jolted again. Not a good place psychologically to fall asleep.

Basically, I want the algorithm to increase pressure when it senses an inhale, not preemptively, because that tends to be a couple seconds too early for me and it keeps waking me up. Is there a setting I can change for this, or should I ask for a different model?

Thanks all.

[kappa]

I found PR flex behavior to be very jarring also. Try switching flex off completely - it might feel like it's hard to breathe out initially but after some time it should feel natural and you wont have that rush of air as you start to inhale. You could also try minimal flex levels.

ResMed PS/EPR feels much more natural to me but I leave that off as well. It has a pressure ramp as you inhale while PR feels like it spikes the pressure.

[OpalRose]

What AFlex setting are you using?

A Flex setting of 3 has been known to cause some periodic breathing and sometimes feels out of sync with your natural breathing.

I suggest setting AFlex to 1 and see how it feels. If ok, try a setting of 2. Which feels more natural to you?

Also, your minimum pressure should be set to 7cm in order for the Flex algorithm to work optimally.

With all that said, if you have an opportunity to exchange for a different model, try for the AirSense 10 AutoSet or the new AirSense 11 AutoSet. The ResMed's EPR works much better than the Phillips Flex.

[Phaleronic]

Is it a-flex or c-flex?  Also try turning it off completely.  I've actually gone back to straight CPAP mode on both my APAP and auto Bipap, it works much better for me and my ahi stays right around 1.2.

[SideSleeper]

I used to have a Phillips 560 machine--before the Dreamstation. I read that C-Flex should be used with straight CPAP pressure, and A-flex with the adjustable pressure (minimum and high pressures selected). I found it didn't do much--love the Resmed and it's EPR function!

[skim]

What AFlex setting are you using?

A Flex setting of 3 has been known to cause some periodic breathing and sometimes feels out of sync with your natural breathing.  

I suggest setting AFlex to 1 and see how it feels.  If ok, try a setting of 2.  Which feels more natural to you?  

Also, your minimum pressure should be set to 7cm in order for the Flex algorithm to work optimally.

With all that said, if you have an opportunity to exchange for a different model, try for the AirSense 10 AutoSet or the new AirSense 11 AutoSet.  The ResMed's EPR works much better than the Phillips Flex.

I was on 6-9 prescription, AFlex 3. Last night went to Flex off, which was a little easier to get to sleep but still had a few pressure pulses even with no flex setting. Tonight will try AFlex 1 with minimum 7.

Could you please clarify why it should be set to minimum 7? Does this mean that the ramp setting starting at a point lower than 7 will also be problematic in conjunction with AFlex?

Next time I see my doc I will ask for ResMed devices, I've heard in multiple places that their EPR works better. Could you go into a little detail why that is so?

[Geer1]

Flex drops the pressure on exhale but will only drop to the minimum pressure the machine can create (4 cm). If I remember right flex only drops the pressure up to 2 cm so 6 cm is actually high enough to get full benefit. Resmed EPR is much more straight forward with 1 subtracting 1 cm, 2 2 cm and 3 3 cm so on a Resmed machine you need 7 cm to get full 3 epr benefits.

I've never fully understood the difrerent flex settings because I haven't clearly seen what changing the setting does to the pressure waveform. There is a diagram in wiki but if it is accurate there would be no difference on the inhalation, just that the higher flex is the faster it would transition to exhalation and the greater the reduction in pressure would be. If this is the case then high flex if uncomfortable should make you feel like it is prematurely ending your breath not prematurely starting it. What likely makes it feel like it prematurely increases pressure is its square waveform quickly increasing the pressure on all levels of flex. To my knowledge this is not adjustable unless stepped up to a bilevel model (by adjusting rise time). If you look up Resmed easy breathe waveform you will see it much more gradually increases pressure.

[kappa]

DS will use pressure pulses during Apneas to determine if your airway is clear, which determines reporting of OA vs CA (and consequent pressure increase or not). These are only brief and not that frequent even during apnea so it's unlikely you would notice them.

What does your OSCAR chart look like? Are you having any events? If you're super sensitive to pressure changes maybe setting a fixed pressure rather than a range might be appropriate (if it gives you good enough treatment).

[skim]

DS will use pressure pulses during Apneas to determine if your airway is clear, which determines reporting of OA vs CA (and consequent pressure increase or not). These are only brief and not that frequent even during apnea so it's unlikely you would notice them.

What does your OSCAR chart look like? Are you having any events? If you're super sensitive to pressure changes maybe setting a fixed pressure rather than a range might be appropriate (if it gives you good enough treatment).

My OSCAR chart of the day I noticed the annoying pulses the most. I didn't fall asleep until an hour or so. Any time I'd be drifting off to sleep, the machine would give a pulse of pressure during the most relaxed part of my exhale. Drove me crazy and gave me anxiety, forcing me to quicken my breath if I didn't want to be jolted. 

Still not sure if what I'm feeling are all those pressure pulse events at the start of the night, or the Flex kicking in with square waveform a hair early as Geer1 says. 

From what I gather from the manual, if the machine detects 80% reduction in airflow from baseline, it gives a pulse of air to check if the cause is obstructive or central -- but I'm just breathing calmly (because I'm still awake). I noticed in OSCAR that the previous patient's data is still visible on the SD card (even though I cleared data through machine UI). Is it possible that the "baseline" is calibrated to this other patient's breathing patterns, and the machine now thinks my normal calm breathing is constantly borderline hypoxic? 

Does anyone know how "baseline" is determined in these machines? Is it per night, per patient, per x previous minutes? This is really driving me crazy...

Here are other people with basically my exact issue: 
- [this forum]/Thread-Pressure-Pressure-pulses-driving-me-insane
- [this forum]/Thread-Equipment-Disconcerting-pressure-pulses-between-breaths-on-Dreamstation-Pro

[OpalRose]

I was on 6-9 prescription, AFlex 3. Last night went to Flex off, which was a little easier to get to sleep but still had a few pressure pulses even with no flex setting. Tonight will try AFlex 1 with minimum 7.

Your latest chart still shows your Flex setting at 3.  I believe I suggested you try a setting of 1 or 2.  A setting of 3 has been known to cause some variable breathing and also a feeling of your inspiration or exhalation cut short.  Breathing just doesn't feel natural.

With that said, the Pressure Pulses are built in to Phillips algorithm and has nothing to do with using a Flex setting.  These are two different things.

From what I understand, the pulses are used to determine if a higher pressure is needed.  The algorithm will raises the pressure up by approximately 1.5cm and goes up and down.  You can see this on your pressure graph.  

I used a Phillips machine for almost 7 years.  It didn't bother me that much, but I can understand if some folk are affected by it.

If the pulses bother you, try a fixed pressure.  Use the Apap mode with a setting of 7min and 7max, with a Flex setting of 1.  This may be a bit lower of a pressure than you need, but should give you more comfort.