Wanting to understand pressure range

[AMK]

Palerider, what I don't understand is that the machine on its own is not going below 7 at any time during the night other than the initial ramp. So if it's keeping itself between 7 and 9, and never dropping down to that 5, how would setting the min pressure to 7 make a difference? Thanks, I'm so tired I seem to need everything spelled out.

I am puzzled why my flow rate is so much worse with the pressure graph going between 7-9 than when it was a steady 8.

[zenon]

I have been using CPAP therapy for nearly four years, with the past couple of years a RESMED S9 Autoset and a nasal mask REsmed Mirage Activa LT. Never used a Humidifier.
According to the data which i read every morning, the pressure is around 10, AHI always less than 1, sometimes 0, average use o f 7.5 hrs and zero leakage.
The pressure starts at 4 and was told that max is set at 12 with ramp time been 20 mins.
I' ve been told by the sleep clinic that these readings are ideal and therapy is working very well.

My concern is that there is no consistecy in my sleep duration. I have never experienced sleep of longer that possibly six hours without interrruption. Mostly it is between 1-4 hours , woken ubruptly anything between 2-4 times a night. Once woken i find it difficult to go back to sleep. When awake i do not feel tired and my mind is preoccupied as to why i am awake?
During the day , admittedly i do not feel excessively tired but on occasions when for an hour or so it does hit me.

I have asked the technicians at the hospital if the machine has been set correctly for my needs, and as far as they are concerned everything is ok and i am made to feel paranoid.

Is anyone else experiencing similar problems? Any ideas why my sleep is broken up?

Many thanks in advance

[grayghost4]

zenon

I would be much better for you to start a new thread with your Question ... rather that add to the end of someone elses thread ... you will not get a proper answer this way.

[AMK]

Thank you, Grayghost, I was going to just start a new thread if this got more confusing.

[AMK]

OK I have put my tired brain through reading the tutorials on how to put sleepyhead data in a post. I will attempt this. The first two are from when the machine was in cpap mode. Ignore the ramp times; I have since figured out that that needs to be a lot shorter.




These next two are from the machine being apap, pressure 5-9:

[Wulfman...]

How do you know your sleep is disrupted by the pressure changes? By being awakened by them?

Are you or are you not using Sleepyhead or some software to actually SEE what's happening?
If you are being awakened, you should be able to see what's going on before you're awakened.

And, if your sleep study/titrated pressure was 8 cm., then that's where the minimum should have been set......not lower.
If you're having more events than are being treated by that pressure, then if the machine will properly respond to your events, it may go higher to address events that need more pressure. Much of it depends on your breathing characteristics.


Den

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[palerider]

Palerider, what I don't understand is that the machine on its own is not going below 7 at any time during the night other than the initial ramp. So if it's keeping itself between 7 and 9, and never dropping down to that 5, how would setting the min pressure to 7 make a difference? Thanks, I'm so tired I seem to need everything spelled out.

I am puzzled why my flow rate is so much worse with the pressure graph going between 7-9 than when it was a steady 8.

the machine *wants* to go below 7, and so it keeps lowering the pressure, plus, it takes a bit more time to get up there.

I'd set the min pressure at 7.6, or, heck, even 8, and see what happens, if it spends a lot of time at 8, then you could consider dropping it a bit, but lower pressure=more flow limits, most likely.

[Wulfman...]

The reason I asked for a range instead of just 8 is that during my sleep study, I had 40 events per hour but just during REM sleep. So the pressure of 8 seemed to just be necessary during REM. I was waking up during the night feeling blasted by air and I wanted to experiment. I admit that on 5-9 now I wake up more exhausted than before I had cpap, but I think that's due to having a mask that leaks (note it leaks tiny amounts, just enough to hit my eyes, not enough to show up as leaks in my "myAir Dashboard"). I'm still trying to sort all this out with very little help from the doctor or DME. I'm only having about 1 event per hour right now...supposedly my treatment is excellent.

I use SleepyHead. It looks like after ramping, my pressure never drops below 7 the entire night, so I'm not sure the 5 setting is hurting because I'm never there.

After looking at your reports, with the amount of flow limitations you have, I suspect that the higher you set your maximum pressure, the higher your pressure will rise. And, in my opinion, it won't squash them without LOTS of (sleep disturbing) pressure. So, what you've traded for (by going to a range of pressures) is more sleep-disturbing pressures chasing flow limitations. You've been having nice, low AHI numbers at straight 8 cm. If you felt like you needed a little more "air" while you're sleeping, going to a straight 10 cm. might be a compromise.


Den

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[AMK]

Are the flow limitations UARS?

[palerider]

Are the flow limitations UARS?

well, some ARS... whether it's in your head, or your throat, that's harder to tell.

[Wulfman...]

Are the flow limitations UARS?

Doing a Google search on "Are flow limitations UARS" yielded a number of links. A couple with some excerpts are listed below.

Here's an excerpt from this link which MAY help.

http://www.sleepscience.com.br/pdf/arti ... _art07.pdf

"ABSTRACT
The upper airway resistance syndrome (UARS) is a sleep breathing disorder described by Guilleminault et al., in 1993, to identify patients that present increased respiratory effort and airflow limitation during sleep associated with an increase in the upper airway resistance."

and, this one:

http://www.atsjournals.org/doi/abs/10.1 ... OuNeSz2QwA

"Abstract

Previous studies have shown that episodes of inspiratory flow limitation can be clinically important. We have challenged the hypothesis that patients with the “upper airway resistance syndrome” have more episodes of inspiratory flow limitation, associated with greater swings in pleural pressure and more arousals from sleep than normal subjects. We thus studied eight symptomatic patients with UARS (ESS > 10, AHI < 15) and eight matched asymptomatic subjects. All had overnight polysomnography with recording of pleural pressure and airflow derived from nasal pressure. Events scored visually using nasal pressure were termed flow limitation events and those using both signals “resistive events.” The patients with UARS had no more episodes of flow limitation or resistive events than the controls. However, pleural pressure swings at resistive event termination were significantly more negative in the patient group ( − 15 [IQR 9–19]; − 11 [8–12] cm H2O; p = 0.02) and the number of cortical arousals associated with resistive events was higher in the patients (median, 10 [5–15]; 3 [1–9]/h slept; p = 0.02). This study confirms that patients with UARS have periods of increased upper airway resistance associated with significant sleep fragmentation. However, resistive events are also common in normal subjects, although these are associated with less negative pleural pressure swings and fewer arousals. Thus, the clinical significance of resistive events needs to be interpreted with caution."


Den

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[AMK]

Thank you, Den; I was doing similar googling. I think you're right in that I could go back to a steady pressure and raise it a little.

[yaconsult]

I don't get it! Why would they provide the latest and greatest of machines that is capable of sensing and adjusting to your needs dynamically throughout the night, and then set it to operate in fixed pressure mode or in a very restrictive range?!

Although APAP machines are capable of operating over a wide range of pressures, sometimes pressure swings can be disturbing to the patient. See Wulfman's posts (an example below) for multiple discussions on the subjuect. Some people believe better APAP therapy results when the machine is set to a narrower range.

Ah, ok - that part I understand, and in fact, that's what I do myself! I have my minimum set to 12.5. I have seen my maximum hit as high as 18, though, and I'm happy that it is able to auto-adjust as necessary. I suppose for some people, setting a limit on the maximum pressure might help as well.

I hope the original poster can find the settings that work best for him. I have managed to reach that point with help from the wonderful folks here - my AHI is often 0.0 and almost always less than 1.0, while my untreated AHI measured in January was 80.2.