straight bipap?

okay so i went from a full auto machine that would somehow decide when i needed to breath...and i HATED it...to an auto cpap machine with cflex...and so far i am doing much better on it! my question is about straight bipap...i think i understand the concept that there is an increase in pressure to a predetermined level whenever you initiate a breath? and then there is an EPAP setting as well...and what about when you hold your breath? would it stay at EPAP setting? and not ramp up to try and initiate a breath? is that correct?

so who is straight bipap intended for? is it if your IPAP setting gets too high or too uncomfortable in straight cpap?

would it help with snoring and hypopneas?

just trying to learn....

Bilevel will deal with your apneas and snoring just fine. As you know it has one pressure for inhale and a lower pressure for exhale. Why would you be holding your breath?A bilevel is not a machine that will initiate a breath for you. Trying to trick the machine doesn't make any sense, let it do it's job. Bilevel has not been proven to be superior to straight CPAP. Some doctors prefer to use Bilevel, just their own preference, or for comfort. Also it does seem to work better for some people with various kinds of SDB. It's good to want to learn about the different modes. Do a search here on the forum for Bilevel or BPAP and you should find plenty of infomation.

drdrew wrote:okay so i went from a full auto machine that would somehow decide when i needed to breath...and i HATED it...to an auto cpap machine with cflex...and so far i am doing much better on it! my question is about straight bipap...i think i understand the concept that there is an increase in pressure to a predetermined level whenever you initiate a breath? and then there is an EPAP setting as well

Yes, that sums up the basics. The drop to EPAP happens as soon as the machine detects the beginning of your exhalation. On my PR System One BiPAP that drop seems instantaneous to me.

...and what about when you hold your breath? would it stay at EPAP setting? and not ramp up to try and initiate a breath? is that correct?

Good question. I'll stick my neck out on a limb and try to remember to do an experiment tonight to see if what I say has any basis in reality.

I'm pretty sure that if you EXHALE before you start holding your breath, the pressure stays at the EPAP setting. Straight bilevels do NOT try to initiate breaths by increasing the pressure in a drastic fashion. They wait for you to start inhaling before switching to the IPAP pressure.

But if you take a great big INHALE and then start holding your breath---before your exhale has started----I don't actually know if the machine will keep the pressure at IPAP (and assume that you're still inhaling) or drop it to EPAP thinking that since you are no longer inhaling, you must be exhaling. If I remember, I'll try this while looking at my display tonight and report back.

NOTE: On the PR System One BiPAPs, if you turn Bi-Flex on, then the machine provides a bit of EXTRA pressure relief on exhale beyond that provided by just dropping the pressure from IPAP to EPAP. In other words, for a brief period of time, the pressure drops BELOW the EPAP setting. And somewhere around half way through the exhale, the pressure is brought back up to the EPAP setting. SOME people can detect that small rise in pressure (I'm one of them). And if you can detect that small rise in pressure, it is POSSIBLE for you to feel like the machine is trying to make you breath when it is not doing that at all.

so who is straight bipap intended for? is it if your IPAP setting gets too high or too uncomfortable in straight cpap?

Judging from what I've read here:

• Some folks are put on BiPAP because they need more than 20cm of pressure (BiPAPs go to 25).
  
  Some folks are put on BiPAP because they have a relatively high pressure (over 15cm) and have a tough time exhaling even with the pressure relief set to its maximum level.
  
  Some folks are put on BiPAP because they have severe aerophagia problems and for many of these folks, the bilevel does alleviate the aerophagia issues.
  
  Some folks are put on BiPAP because they just can't seem to tolerate CPAP/APAP and they or their doctor think that a trial run on BiPAP may make them more comfortable with the therapy since many folks (not all) do find breathing with a Bilevel feels more normal.

would it help with snoring and hypopneas?

Yes---in the same way CPAP/APAP helps with snoring and hypopneas. During a bilevel titration, hypopneas are typically used to increase only the IPAP pressure. Snores and obstructive apneas are used to increase the EPAP pressure (and the IPAP, but only if IPAP - EPAP is at the minimal level for the lab doing the titration.)

drdrew wrote:...and what about when you hold your breath? would it stay at EPAP setting? and not ramp up to try and initiate a breath? is that correct?

You may be thinking of a bi-pap ASV...which handles centrals and other breathing disorders. When the machine senses that you are not breathing (or if you were holding your breath) it ramps up the pressure to keep you breathing.

Thanks guys, helpful info! I am using cpap with flex on right now...sort of bipap but I guess the pressure starts to rise up after my exhale on it's own...and with bipap now I am assuming it would wait for me to inhale...anyway I'm interested to see what your "experiments" show!

drdrew wrote:Thanks guys, helpful info! I am using cpap with flex on right now...sort of bipap but I guess the pressure starts to rise up after my exhale on it's own

That's the FLEX that you are noticing. With Flex turned on, the pressure is lowered at the very start of your exhale, but the pressure is supposed to increase back up to your therapeutic pressure before you start to inhale. And some people notice it. And it can indeed feel like it is rushing you to breath. You MIGHT want to consider turning Flex OFF because you might be more comfortable with no flex instead of flex.

While Resmed's EPR is rumored to wait until it senses you starting to inhale to bump the pressure back up to full therapeutic levels, PR's Flexes definitely do not wait until it senses you are inhaling to get the pressure back up.

The plain C-Flex system adjusts the pressure on exhale as shown below. Note that in the patient flow curve, inhaling is ABOVE the dotted line and exhaling is BELOW the dotted line. And that flat part of the curve near the dotted line? Well, the vertical lines indicate that PR still regards that as part of the exhale and certainly that's how I feel about my own breathing pattern. Others may differ, however. Note how the pressure increases BEFORE the exhale is done.



C-Flex Plus is shown below. In C-Flex Plus, the transition back to full therapeutic pressure is a two step process. Note that FULL therapeutic pressure is at the TOP solid line on the pressure curve. The first step increases the pressure part way back to FULL therapeutic pressure during the second half of the exhale. The second step finishes the increase back to FULL therapeutic pressure and happens once the inhale starts. Also note the "rounding" so the transitions between pressures are not so sudden.


A-Flex (the exhalation relief system for the System One AUTO) is similar to C-Flex Plus. The only difference here is that the therapeutic pressure can change in response to detected events:

...and with bipap now I am assuming it would wait for me to inhale...anyway I'm interested to see what your "experiments" show!

On the PR System One BiPAP, the equivalent system is called Bi-Flex. If you don't turn Bi-Flex on, then there will be no increase in pressure until you start to inhale. The reason why is simple: With Bi-Flex turned off, the pressure never drops below EPAP.

But when Bi-Flex is turned on, it's a different story. Bi-Flex is shown below. That top dotted line in the pressure curve is the IPAP pressure. The bottom dotted line is the EPAP pressure. Note how turning Bi-Flex on makes the exhale pressure dip BELOW the EPAP setting. And note how the pressure comes back up to the full EPAP setting before the start of the inhalation.


Personally, when my pressure was still at 8/6, I found Bi-Flex to feel like the machine was trying to rush my breathing---trying to make me inhale before I was ready to because I could feel that small, subtle increase in pressure back up to my EPAP of 6cm. So I just turned Bi-Flex off because I really didn't need any additional pressure relief. The relief caused by dropping from 8 to 6 was plenty for me. My guess is that since you are noticing the pressure increase in C-Flex when you're not done exhaling, you will probably also notice the pressure increase in Bi-Flex. But you may find that you don't need Bi-Flex turned on to breathe comfortably with a BiPAP.

You can read more about the Flex family at http://www.healthcare.philips.com/main/ ... efault.wpd

drdrew wrote:... so who is straight bipap intended for? is it if your IPAP setting gets too high or too uncomfortable in straight cpap? ...

And we're happy to help you learn!

You essentially have the answer correct. But it's not just if the pressure is uncomfortable. It could be that someone has problems with air getting into their stomach / digestive system. The lower exhalation pressure can help. Or it might be that breathing against higher pressure triggers arousals. BiLevel therapy might help with that. About two or three years after I started CPAP, I started to have problems with sleep again. The sleep tech switched me to BiLevel and that did the trick. On CPAP there were all sorts of arousals (when I would move from deeper to lighter levels of sleep for no clear reason). On BiLevel most of those just went away. It was a clear difference in my sleep.

Of course, that's just my own experience. Others might have other reasons why they move to BiLevel therapy.

Hope that helps.

okay first of all robysue ur my frikken hero! thanks for taking the time for that excellent tutorial! i have to admit i have learned a ton since i joined here and the more i understand i think the better i can do. i am lucky that my dme lets me experiment with masks and machines almost at will. i get that everyone is different and for right now ive had much better luck with cflex(though i turn flex down to 1) than i EVER had with my auto machine. still tweaking to get everything as optimal as possible since 6 hrs mask on is still a "good" night for me. anyway thanks again this forum is an amazing resource.

drdrew wrote:my question is about straight bipap...i think i understand the concept that there is an increase in pressure to a predetermined level whenever you initiate a breath? and then there is an EPAP setting as well...and what about when you hold your breath? would it stay at EPAP setting? and not ramp up to try and initiate a breath? is that correct?

A straight bi-level (bipap is Respironics name for bi level, ResMed calls theirs VPAP) has inhale (IPAP) and exale (EPAP) pressure settings. A straight bi-level is likely to run in simultaneous mode only and won't ramp up to try and initiate a breath.

drdrew wrote: so who is straight bipap intended for? is it if your IPAP setting gets too high or too uncomfortable in straight cpap?

When I sleep on my side (90% of my sleeping) I don't have OSA but I have enough RERAs to create sleep problems so I probably have UARS. I use a bi-level because even with ResMed's EPR set to 3 which made my S9 AutoSet function like a bi-level with EPAP set 3 less than IPAP, the effort to breathe out against pressure was too much work when my asthma got worse last winter.

We tried reducing the pressure while running the S9 Autoset as a cpap and I was still unable to sleep with cpap half the time. With the bi-level I am using xpap consistently. I quickly learned that if IPAP is too low it also creates problems with the asthma. The S-9 VPAP identifies very few events so the EPAP is high enough to prevent apneas when I roll on my back and I am fine tuning the IPAP to eliminate flow limitations which should prevent RERAS.

drdrew wrote:and then there is an EPAP setting as well...and what about when you hold your breath? would it stay at EPAP setting? and not ramp up to try and initiate a breath? is that correct?

Correct. With plain bilevel (not set for a "timed" backup rate) If you are exhaling (or have just finished exhaling but have not started to breathe in again) and you hold your breath, the machine will stay at EPAP. It will stay there until you start to breathe in again.

If you were breathing in (using IPAP) and started holding your breath, it would drop down to EPAP and stay down there until you start to breathe in again.

An exception to that would be if something changed in your airway while you were holding your breath. If you swallowed, for example, or made a slight throat clearing sound/movement while holding your breath, the machine might interpret the subtle change in pressure of your airway as you starting to inhale again, even though you were not. It might switch up to IPAP then.

The Respironics (Philips Respironics) machines seem to be more likely to switch to the "wrong" pressure (switching up to IPAP while you're still exhaling, or switching down to EPAP while you're still breathing in) for some people. Something about the "digital tracking" of Respironics BiPAP machines doesn't suit some people as well as ResMed's VPAP (their trademark name for their bilevel machines) does. If I were a new user prescribed "bilevel", I'd want the ResMed VPAP rather than the Respironics BiPAP, in case I was one for whom "digital tracking" didn't fit my breathing well.

About your question... "what about when you hold your breath? would it stay at EPAP setting?" Sometimes the sleep doctors don't know the answer to that very basic fact about bilevel machines. Can be true even of "sleep doctors" who use bilevel themselves.
viewtopic.php?p=233928#p233928

rested gal wrote:... If I were a new user prescribed "bilevel", I'd want the ResMed VPAP rather than the Respironics BiPAP, in case I was one for whom "digital tracking" didn't fit my breathing well. ...

I've used both machines. I tend to concur. However, one additional reason I prefer ResMed VPAP over Respironics is that ResMed developed "Easy Breathe" technology that actually does make it easier to breathe with the BiLevel therapy:

http://www.resmed.com/us/products/s9_se ... nc=dealers
http://www.resmed.com/us/assets/documen ... er_eng.pdf
http://www.sleepdt.com/resmed%E2%80%99s ... rew-terry/

Some light reading to help you get some sleep ...