My observations APAP ranges

My doctor asked me to increase the range on my APAP. Just a bit on the bottom but a lot on the top. He claimed that the machine would go where it should be, but I complained that I thought the machine ran all over the place when I had a wider range. Well I set it on what he suggested anyway and it seems the machine does stay pretty much within the 9-11 range. I used to have it set on 6-12 and on that range it really did run all over the place. So I was thinking maybe if the bottom part isn't high enough then it runs all over but if only the top part is higher than you need the run away pressure changes don't happen so much. Does that sound about right in your experience?

My experience, and I think that of many others, is that the minimum needs to be within a few centimeters of your needed pressure, or it can take too long for the machine to react.

The maximum doesn't really matter, unless the machine tends to "run away" to a high pressure for some reason. Then the maximum may need to be lowered to reign that in. To my way of thinking, though, if the auto tends to "run away" like that with someone, that someone may not be a good candidate for an auto.

What is your titrated pressure?

Ultimately, narrow ranges seem the most popular.

However, when starting out, you may be using a higher top pressure to see what pressures your events take the machine.

Georgio

Even though the machine reports my AHI as really low (less than 1.0), leaks are ok too, I'm still waking up every now and then gasping for air...machine is on, mask is on, not leaking, lying on my side etc. When I download the card I see the break in the therapy line because I've torn the mask off and shut the machine off because I'm in a choking panic. I also noticed that before that happened the machine has not always reacted to anything. It's a flat line across on the lowest pressure. No hypopnea or apnea is recorded. So I asked my doctor if it's possible that I could be having breathing events that arouse me but that the machine does not recognize or record. He said it was possible yes and then said it could be an issue with the machine not sensing that I'm having an event. He suggested there might be something wrong with the machine. Well, I've already returned my other machine and this is a loaner and it's happened a couple times with the loaner too. So he suggested that I raise the pressure anyway. But after a few days of this higher pressure (only .5 higher on the bottom), I noticed it pretty much stays in the range I had it in anyway. But like I said when it was much lower on the bottom (several months ago), it was up and down all over the place. So I figure right around 9 or 10 is the main pressure I need since it stays around that anyway even though I've raised the top end to 17. I just don't know why I'm still waking up gasping sometimes. Although my doctor did mention it might be central apneas. I guess ultimately it's a mystery, but I do wonder just how much it's still disrupting my sleep since I'm still excessively sleepy during the day despite using this machine and it reporting a great result.

Georgio wrote:What is your titrated pressure?

Ultimately, narrow ranges seem the most popular.

However, when starting out, you may be using a higher top pressure to see what pressures your events take the machine.

Georgio

jnk wrote:My experience, and I think that of many others, is that the minimum needs to be within a few centimeters of your needed pressure, or it can take too long for the machine to react.

My experience has been the opposite of that. When it was low on the bottom end it reacted to every little thing. I'd be awake and looking at the little screen and it would be raising and lowering the pressure. It doesn't do that now that I've raised the bottom pressure.

nobody wrote:My doctor asked me to increase the range on my APAP. Just a bit on the bottom but a lot on the top. He claimed that the machine would go where it should be, but I complained that I thought the machine ran all over the place when I had a wider range. Well I set it on what he suggested anyway and it seems the machine does stay pretty much within the 9-11 range. I used to have it set on 6-12 and on that range it really did run all over the place. So I was thinking maybe if the bottom part isn't high enough then it runs all over but if only the top part is higher than you need the run away pressure changes don't happen so much. Does that sound about right in your experience?

It depends.

Unlike CPAP which maintains a "constant" pressure, an APAP depends on airflow feedback within your system. So it is much more sensitive to system leaks than CPAP, and is also more sensitive to exhalation relief settings than it is in CPAP mode, and it is also sensitive to people with central or mixed apnea events.

So ... if your leaks are completely under control (ie. you mask leak is both steady and equal to the designed mask leak) and you are not one who exhibits central or mixed apnea events and you account for exhalation relief ... then setting your min pressure to just under your titrated (or long-term minimum pressure) and setting your max pressure wide open should be just fine. One other variable that may affect the performance of your APAP is the mask type ... I have found that full face masks having a larger dead-space volume possibly affects the transient response of airflow to the machine sensor. But that is more likely to affect the AHI scoring more so than run-away pressures ... but since they are tied together it could indirectly cause run-away pressures too.

If you are using AFLEX (or any other) exhalation relief, I would account for that by raising the min pressure one or two centimeters above what it would be if no exhalation relief was being used.

To use an APAP machine correctly, you really need to have the software to be able to determine what all is going on with your leaks, pressures, and apnea/hypopnea events throughtout the whole sleep session. Otherwise you can end up chasing one of several tails and end up at square one. I believe APAP to be superior to CPAP machines but only if they are used with the software.

If it is staying in the 9 to 11 range, I would set min pressure to 8 (and leave exhalation setting to what ever it was for collecting your 9 to 11 data) and if all leak and central/mixed apnea conditions allow, set the max wide open and see what happens after a week or two of data. Again, your leaks should be steady and within acceptable range of mask design else my suggestion or anyone elses mean nothing.

nobody wrote:My doctor asked me to increase the range on my APAP. Just a bit on the bottom but a lot on the top. He claimed that the machine would go where it should be, but I complained that I thought the machine ran all over the place when I had a wider range. Well I set it on what he suggested anyway and it seems the machine does stay pretty much within the 9-11 range. I used to have it set on 6-12 and on that range it really did run all over the place. So I was thinking maybe if the bottom part isn't high enough then it runs all over but if only the top part is higher than you need the run away pressure changes don't happen so much. Does that sound about right in your experience?

Unfortunately, this type of thinking is rampant among the sleep doctors who are willing to prescribe an APAP machine. And, it's WRONG. As was mentioned previously, it can take a lengthy period of time for the pressure to rise to what is needed. Most machines will rise pretty quickly on leaks and snores, but when it comes to the actual apneas and hypopneas they move more cautiously. I don't suppose he ordered that you wear a pulse-oximeter while you use the range of pressures? If your sleep events (including leaks and snores) were similar for those nights in the wider range, your pressure would be falling consistently in a certain range of pressures......BUT......that doesn't mean that the minimum pressure is high enough. There was a thread on the forum a few days ago where the person stated that as he moved his minimum pressure up, his average and 90/95% pressure was also moving up......and that's what we're talking about......the minimum pressure needs to be at or as close to the point where it will take care of almost ALL of the events. If a person is prone to mask leaking, then the maximum pressure needs to be reigned in or the person needs to use straight (CPAP) pressure. At a single pressure (that will take care of almost all of the events), you snore and leak all you want and there won't be any pressure changes to disturb your sleep.

Edit: (I just read your post above this one).
Was the pressure at its lowest point where you were gasping for breath? (that's the way I read it)
It would be wise to go into the setup on this machine and check ALL the settings.....and make sure that the "Split-night" is not turned on (depending on which machine you're using).
If your loaner machine is the M Series Auto, the setting should be this:
Split Night Time = Off (options are Off, 120, 180, 240) Should be "Off"


Den

nobody wrote: My experience has been the opposite of that. When it was low on the bottom end it reacted to every little thing. I'd be awake and looking at the little screen and it would be raising and lowering the pressure. It doesn't do that now that I've raised the bottom pressure.

That's where your experience is flawed, if you are not asleep the numbers on the screen or what the machine does are not being treated, you have to have the software and reader to get the real treatment data, and then it's only going to show what's going on correctly for the times that you are asleep. The machine is only made to keep your airway open while you are asleep, the rest of the time it's just blowing air. It need your sleeping input to adjust what you need. Jim

Central or Obstructive the machine should still sense it as an OA. Den makes an excellent point above. If that doesn't fix it kindly describe your setup in detail, incl. machine make model, settings, hose length and mask. Even sleeping position.

Yes I did check the settings on this machine and the one I sent back to respironics. The split night thing is off. The auto off feature is off. It is sometimes on the lowest point when I wake up gasping, sometimes it has responded and is up at a higher point. So it's a bit inconsistent. I agree hat the ffm doesn't allow the machine to sense as well. The pressure seems a lot stronger with a simplicity nasal mask. I really don't like the nasal mask tho. I have too much congestion and I can't seem to tolerate the pressure with the nasal mask, even with the cflex on. What is meant by "stable" leak? It is never a flat line across, it goes up and down a bit, but never more than what the manufacturer says it should be anyway, it's usually lower than that. No the doctor did not order me an oximeter, I've been wanting to buy one anyway, just not sure which one. I sure would like to get it resolved so I would hopefully not have to take stimulants in the daytime...since I cannot tolerate them anyway and struggling to keep up with life.

OK I guess this is too confusing for me. Should I just put it on a straight CPAP, raise the bottom pressure ...or? I would rather not lower the bottom pressure because 9 seems pretty good and 8.5 still felt like my throat was falling closed as I fell asleep.

nobody wrote:Yes I did check the settings on this machine and the one I sent back to respironics. The split night thing is off. The auto off feature is off. It is sometimes on the lowest point when I wake up gasping, sometimes it has responded and is up at a higher point. So it's a bit inconsistent. I agree hat the ffm doesn't allow the machine to sense as well. The pressure seems a lot stronger with a simplicity nasal mask. I really don't like the nasal mask tho. I have too much congestion and I can't seem to tolerate the pressure with the nasal mask, even with the cflex on. What is meant by "stable" leak? It is never a flat line across, it goes up and down a bit, but never more than what the manufacturer says it should be anyway, it's usually lower than that. No the doctor did not order me an oximeter, I've been wanting to buy one anyway, just not sure which one. I sure would like to get it resolved so I would hopefully not have to take stimulants in the daytime...since I cannot tolerate them anyway and struggling to keep up with life.

Could you tell us WHAT the lowest point is?......4 cm? (or is it higher?) In any case, the gasping at a pressure that's TOO low is, in all probability BECAUSE it may be too little pressure to expel the CO2. As has been discussed before on the forum, some feel it could take at least 6 or 7 cm. to be able to vent the person's carbon dioxide.....and that may depend on the individual. In my case, I've never tried a pressure less than 10 cm., but from that, I don't think I'd want to go lower than 8 or 9. Below that, I may feel like I was suffocating.

Den

I have run my machine many nights at a cpap pressure of 8. I typically have an AHI of 5.0 with AI of 0.8. I have also run the machine many nights at an apap pressure from 8-20. My 95% pressure is typically 13 when on apap and my AHI is 5.0 with AI of 0.8. Make any sense out of that if you can.

It was set on 8.5 - 10 and I was waking up gasping now and then. It is currently set on 9 - 17, so far no waking up and gasping, but it has only been on that for a few nights.

nobody wrote:It was set on 8.5 - 10 and I was waking up gasping now and then. It is currently set on 9 - 17, so far no waking up and gasping, but it has only been on that for a few nights.

Like I said, the minimum tolerated pressure will vary among individuals.

Den