APAP Questions

[lawdognellie]

Okay, I finally decided to break down and buy my own APAP machine (insurance denied coverage even through have Rx). I just have a few questions about APAP machines in general?

I was reading someone's earlier post and thet talked about having an APAP machine set between 12 and 14. If an APAP machine auto adjusts, why would you set a pressure? Also, is ramp mode actually necessary when using an APAP? The only time I've used an APAP was during my titration study. The machine was set from 4-20 and I never had to hit ramp, etc. Machine would just stay at 4 until I fell asleep and then increase until it found the minimum to prevent events? Isn't that the way the APAP is supposed to work?

Sarah

[Snoredog]

Most autopaps have a minimum and maximum pressure range. That is the 4cm to 20cm. By default most come from the factory with that range set. Most people find that 4.0cm is too low as the starting pressure (you can starve for air just laying there falling asleep).

Ramp is another feature found on the newer models.

Up until a couple years ago, autopaps did NOT have a Ramp feature. Ramp was only found on straight CPAP machines or machines in cpap mode. For example, if your titrated lab pressure was 10cm, you could set the machine to "ramp up" in pressure from a lower pressure to allow you to fall asleep more easily then increase to your final pressure. For example 6cm to 10 over 30 minutes, the machine would start at the 6.0cm then increase every 5-minutes by .5cm until the timer value expired or the pressure reached.

In a PSG lab, they don't usually use basic autopaps patients use, they use special machines with a direct cable interface and they control them from the monitoring room where the techs are.

Do you need Ramp? All depends on your titrated or 90% pressure. If you wake up during the night the machine might be blowing at that higher pressure, this can make it more difficult to fall back asleep. So by setting up and then hitting the Ramp button you can drop the pressure (or take control) of the machine forcing it back to the lower starting pressure. This again allows you to more easily to fall asleep where the machine takes over again with automatic titration pressure.

The Resmed machines have a feature called Settling. This has a timer associated with it, when you enable it for example 30-minutes the Resmed machine will stay at the Min(imum) pressure set until that timer expires even if an apnea event is seen.

The new M series auto has a new feature called "AutoRamp". it is basically the ramp found on cpap machines but has a pressure range associated with it.

For example, let's take that 12cm to 14cm range you spoke of, in that case, the machine could be set up with a AutoRamp to make it easier for the patient to fall asleep then turn over therapy mode to the machine.

So here is how that machine could be set up to use AutoRamp:

Minimum pressure=12.0cm
Maximum pressure=14.0cm

AutoRamp pressure range start=6.0cm
AutoRamp pressure range end=12.0cm (always is the Minimum pressure set).
AutoRamp timer=45 minutes.

Theory of Operation:

With the above settings, patient would put on mask, hit the machine On button, pressure starts at 12.0cm, patient hits the Ramp button, pressure immediately drops to 6.0cm and then starts ramping up in .5cm increments for 45-minutes until it reaches the Minimum set pressure of 12.0cm. Once the 45-minute timer expires the machine switches to auto titration mode and responds to events. Note: On the M series, the machine will not respond to SDB events until that timer expires.

Now if during the night the patient is awakened and machine is blowing at 14.0cm making it more difficult to fall back asleep, the patient can hit the Ramp button on top and machine will immediately drop pressure to the set 6.0cm and the timer resets.

If you see on your PSG that latency to REM is 30-minutes, you may want to lower the timer down to more closely match that. I find 30-minutes works well.

If the autopap is responding to your needs, there is no reason to set a range like 12cm to 14cm. Some doctors are old school and have no faith in how these machines respond. I do believe they should have a pressure limit set especially if you are at risk of central apnea.

[rested gal]

If an APAP machine auto adjusts, why would you set a pressure?

Speaking only for myself, I set a lower pressure pretty close to the pressure I'd likely be prescribed from a full PSG titration. I already know through simply experimenting that my throat slams shut even when I'm wide awake if I deliberately let it relax as much as possible. I can allow it to do that while sitting right here at the computer, if I consciously relax my throat as much as possible. Through further experimentation, using several straight cpap pressures while lying down, I determined that will happen unless I'm using at least 8 cm cpap pressure. I figure the more complete relaxation during sleep is going to need even a tad more minimum for me, right from the get-go. So I have the low pressure of my range set at 9.

That might sound like, "Well, what's the use of having an autopap if you're going to set the low pressure up pretty close to or at 'prescribed pressure'?" For me, the benefit of having an autopap is because 9 or 10 takes care of preventing events most of the night. But my OSA hits harder during REM when the muscles are at their most relaxed. Occasionally my autopap will go up as much as 5 or 6 cm's more on some nights. More often than not, it's toward morning when the increase happens on the data. The longest REM period we have is usually near morning. So....I like being able to use a pressure ( 9 ) that I know pretty much handles preventing apneas for me, AND having a margin up above (I set the high for 16, which it almost never touches) for the hour or so during most nights when a little (or a lot) more is needed.

Just because an autopap can range from 4 - 20 doesn't mean that's the best way for everyone to use an autopap. For some that would be fine. For others, bringing the lower pressure up a little more, or even considerably more, makes the treatment go more smoothly.

Also, is ramp mode actually necessary when using an APAP? The only time I've used an APAP was during my titration study. The machine was set from 4-20 and I never had to hit ramp, etc. Machine would just stay at 4 until I fell asleep and then increase until it found the minimum to prevent events? Isn't that the way the APAP is supposed to work?

Ideally yes. It would be nice if APAP worked that simply at that wide open range for everyone. Some people, however, find 4 cm's or even 5 cm's stifling when breathing through a mask, particularly some masks. Starting at a pressure of 9 doesn't bother me, but if it did, then I'd welcome being able to set a separate ramp pressure lower, even if I wanted the ramp to be finished and be up to 9 within 5 or 10 minutes.

Some people's sleep disordered breathing is, for want of a better word, gradual, giving the machine plenty of warning that the air flow is becoming restricted, so the machine has time to adjust upward slowly (as autopaps are supposed to do...don't want them yo-yo'ing up and down abruptly, which could disturb sleep) to correct the flow limitation.

Others might have more sudden apneas depending on sleep position and sleep stage. Not usually a problem if the machine had already happened to move up to deal with flow limitations and is pretty close at what it would take to clear that apnea anyway. But if the machine was rocking along down at 4 or 5 and a sudden apnea hit that 10 cm's normally would have prevented, it can take awhile for the machine to move the pressure up. That's another reason that I, personally, would rather have the low pressure up pretty close to 'prescribed' pressure. Of course, that's assuming that the sleep study titration was a good one.

Some people may (imho) get titrated for a "worst case scenario" (on their back and in REM) when they actually spend little, if any, time ever sleeping on their back at home. That's where software can be of benefit with an autopap, to see how much time one actually does need "prescribed pressure". If not very often, then those people benefit from lowering the minimum pressure, yet still having a range above when briefly needed.

There are a lot of ways to set an autopap to have it work best for various people, including 4 - 20. Or even setting it to straight cpap mode, if it so happens that a single pressure is best. Very versatile machines, those autopaps.

[Goofproof]

APAP responds better if the range is close to your CPAP pressure. A setting of 2 or 3 cm under cpap pressure to 2 or 3 cm over, sometimes the over need to be closer to CPAP pressure.

The ramp is not necessary, unless you have trouble, I started at 14 cm, no ramp, no trouble, it's a mind thing.

APAP, with the software can give you the lowest pressure and the best treatment, for most people. The Remstar APAP, can give you exhale relief in APAP mode, Resmed can't provide this service. 4 to 20 Cm setup for APAP is the worst use of APAP, DME failure mode I call it. Jim

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