Flow Limits How to Upgrade CPAP to Bilevel

[Deborah K.]

I have finally gotten my leaks under control, but my flow limits don't look great to me.  I'm already using EPR full-time at 3, so that's not the issue.  Is there anything else I can do to drop them, or should I just not worry about it?

Here's last night's Oscar:      

[staceyburke]

The only option you have with your cpap is to raise the min pressure.  I would go up .2 per day until you like the results.

[Deborah K.]

Thanks, Stacey, I did not know that raising the minimum would make any difference with flow limits.  I'll jump to 13 tonight.  I think I will bump the upper limit to 19 also, as I notice that I sometimes bump against the 18 I have set.

[PeaceLoveAndPizza]

You can also consider getting a Bilevel which will likely not only get rid of the bulk of the flow limits but possibly allow a reduction in pressure as it seems to be your flow limitations that are forcing you to use high pressure. You can get one from the suppliers on the wiki or find one used on Facebook marketplace/Craigslist (caveat emptor).

For now follow Stacey's advice of trying a bit more pressure. You don't have much room left before you max out the machine, but worth a shot.

[Sleeprider]

I agree with PLP above. You might be able to get a script from your doctor, but getting insurance to pay will be challenging. The path I took to bilevel was to buy a used machine and demonstrate the efficacy using the data. That was sufficient to get my prescription and my insurance went with my physician's recommendation after an initial denial and appeal. Now I'm on Medicare and received a new Vauto. Since flow limits are not a metric in most sleep tests, and most of us resolve apnea with CPAP, it is very difficult to get a bilevel based on the conventional medical necessity path. Resolving flow limits will reduce your arousal rate and improve how you feel by significantly reducing the respiratory effort that occurs with flow limits (inspiratory flow resistance). As you know, it is the pressure support that resolves flow limits. Sometimes 3-cm is not enough.

[Jay51]

Deborah, I just wanted to post that your tidal volume (the amount of air you take in with each individual inhalation) in your OSCAR (median of 220) seems low.  You have the blueprint now as to how to proceed.  Possibly raising pressure on your cpap could work, or a bilevel could work also by reducing your flow limitations.  Great job posting that chart to get suggestions.  Try to use that specific number (220 tidal volume) on this OSCAR chart as evidence to help you get what you need from your medical providers.

[Deborah K.]

Yikes!  I never dreamed that I might need a bi-level.  Well, I'll see how it goes in the next few nights, then reassess.

I have noticed over time that I was uncomfortable with my starting pressures, so I gradually moved up.  And I increased the upper pressure as I saw myself bumping against the upper limit on Oscar.  I am almost to the upper limit provided by my machine, so maybe a bi-level is, or soon will be, necessary.  Rats.

[Sleeprider]

Bilevel is the CPAP everyone should have. Resmed made their CPAP a bilevel, but limited to 3-cm of pressure support (EPR). So why doesn't everyone get bilevel? Simply the cost that insurance chooses not to pay. Why is bilevel more expensive? Because that is the manufacturer business model, the equipment is identical except for firmware (programming).

When you consider an airway that restricts peak flow, pressure support is how flow can be restored, without increased respiratory effort. It's different from just preventing obstruction by stenting the airway with positive pressure, it is a mechanical assistance to overcome airway restriction at the moment it is needed to produce normal flow. CPAP actually keeps the airway patent during the transition from exhale to inhale. Pressure support is what keeps it patent during peak inspiratory flow. With bilevel, the EPAP pressure can be greatly reduced for individuals like you. The assistance of pressure support during inspiration makes acquiring a breath faster, and more efficient. If you go this route you will wonder why you waited so long. You seem to have the determination to make it happen one way or another. We're here to help if you need.

[Deborah K.]

Am I right that I will need a new sleep study to obtain a bi-level?

[Sleeprider]

Actually, my suggestion is that you try to acquire a self-financed used machine to try out bilevel and self-titrate. It's just easier and cheaper unless you have really good insurance. If you can arrange a test that seeks to minimize arousals and respiratory events using bilevel, it may be worthwhile, however most tests have an endpoint of efficacy where events are minimized and the patient achieves REM sleep with CPAP. It might be worth discussing your concerns and lack of comfort with your doctor. Show them the result of CPAP with little or no EPR vs your use of EPR at 3 and point out how higher pressure support (EPR) results in greater comfort and efficacy in terms of flow limits, ventilation or whatever metric we can help you identify to contrast. Explain that in your opinion greater PS, only available with bilevel may resolve these high flow limits which are disruptive to sleep and cause higher levels of respiratory effort. If you can go into a test with a set of titration outcome objectives beyond routine sleep lab titration, it may be worthwhile. Without that, it's best to just DIY then prove to your doctor how much better bilevel works and feels.