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New user confused
#1
Hi everyone,

First post and all. Good health other than sleep apnea diagnosed during a sleep study (which I slept all of about an hour).

Recently I downloaded the latest version of Sleepyhead and have noticed a pattern where the flow rate pressure often increases right before on OA, Hypopnea or CA event. What confuses me is the pressures and waveforms are normal BEFORE the events. I assumed that when an event occurred, then the pressure would rise in response to that. So can a pressure spike CAUSE an event or is it the result of an event?

I am using a Respironics Remstar system one auto a flex (pressure 8-12) with my AHI running 4-6 on average. I have about 5-6 Clear Airway events/night; 10-20 hypopneas; 10-25 obstructive apneas.

Sometimes I wear a pulse ox that records data. Last night it showed 25 events: Basal sp02 97.8%; Average low sp02 93.6%; Minimum sp02 87%. Doc wants another sleep study but insurance won't pay.

Thanks very much in advance!

Monte
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#2
(07-13-2013, 09:47 AM)montehotbike12 Wrote: Hi everyone,

First post and all. Good health other than sleep apnea diagnosed during a sleep study (which I slept all of about an hour).

Recently I downloaded the latest version of Sleepyhead and have noticed a pattern where the flow rate pressure often increases right before on OA, Hypopnea or CA event. What confuses me is the pressures and waveforms are normal BEFORE the events. I assumed that when an event occurred, then the pressure would rise in response to that. So can a pressure spike CAUSE an event or is it the result of an event?

I am using a Respironics Remstar system one auto a flex (pressure 8-12) with my AHI running 4-6 on average. I have about 5-6 Clear Airway events/night; 10-20 hypopneas; 10-25 obstructive apneas.

Sometimes I wear a pulse ox that records data. Last night it showed 25 events: Basal sp02 97.8%; Average low sp02 93.6%; Minimum sp02 87%. Doc wants another sleep study but insurance won't pay.

Thanks very much in advance!

Monte

Monty:

I am sure there is a post with how to understand data but I can't find it.

Hang in there and someone will be along shortly and steer you in the right direction.

Coffee
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#3
Hi monte,
WELCOME! to the forum.!
Hang in there for answers to your question.
Best of luck with CPAP therapy.
trish6hundred
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#4
Thanks folks for the friendly intro! I also have a clinicians manual in case I need to change pressures. I have not done so but am thinking about it if I get too many CA's due to higher pressure.

Monte
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#5
5-6 CA events each night is not too bad. How long have you been using the machine? Sometimes it can take a while for the body and brain to adjust.

The O2 average of 93 is good. The low of 87 though is not. You can integrate the SpO2 readings into SleepyHead or at least look at the time line to see what was happening with your sleep at the same time.

What is your AHI average? My bet is your OSA is not adequately controlled just yet. Lowering the pressure may cause more OA events which isn't good.
PaulaO2
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#6
(07-13-2013, 12:30 PM)PaulaO2 Wrote: 5-6 CA events each night is not too bad. How long have you been using the machine? Sometimes it can take a while for the body and brain to adjust.

The O2 average of 93 is good. The low of 87 though is not. You can integrate the SpO2 readings into SleepyHead or at least look at the time line to see what was happening with your sleep at the same time.

What is your AHI average? My bet is your OSA is not adequately controlled just yet. Lowering the pressure may cause more OA events which isn't good.


I have been using the machine about 2 mos. My AHI average is around 5. You are right...I do seem to have alot of obstructive events. See screen clip.

Thanks again! Smile


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#7
Hi Monte. Welcome to the forum.

While an apnea event will trigger a rise in pressure in an auto CPAP machine, that is not the only trigger. If the machine detects vibrations in your inhalation that indicate that you are snoring, it will increase the pressure. If the machine detects a "flow limitation", it will also increase the pressure. A flow limitation is a flattening of the flow rate at its peak. In other words, instead of a rounded curve, it looks more like a square wave. That indicates that your airway is partially obstructed, limiting the total airflow, and probably signifying an apnea event is forthcoming.

So you can see that the machine can detect a forthcoming apnea event and raise the pressure to try to prevent it. However, if your pressure settings are too low, the raise in pressure might not be enough to prevent the apnea event, so it might look like the rise in pressure triggered the apnea event, whereas the opposite is true - it tried to prevent the event, but didn't act "vigorously" enough.

Looking at your flow rate graph, that looks very similar to mine when my pressure was set too low (eg. when I rolled onto my back). I will echo PaulaO2's (implicit) advice to not lower your minimum setting. If anything, it looks like it wants to be raised.

There was another recent tread discussing auto-CPAP pressure ranges which discussed the setting of the upper limit. I believe the consensus is that, as long as you can stand the pressure (ie. have gotten used to it), there is no reason not to set your upper limit to its maximum value (20 for your machine). If the machine decides that you need a higher pressure, there is typically no reason not to provide it. And the machine should not raise the pressure beyond what you actually need.

Don't worry about clear-airway events for now. Get your obstructive apnea under control. And, when looking at your data, make sure you ignore any events that happen while you are awake. It is easy to hold your breath while you shift positions, and since the machine doesn't know you are doing that consciously, it counts it as an apnea event.
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#8
(07-14-2013, 01:03 PM)RonWessels Wrote: Hi Monte. Welcome to the forum.

While an apnea event will trigger a rise in pressure in an auto CPAP machine, that is not the only trigger. If the machine detects vibrations in your inhalation that indicate that you are snoring, it will increase the pressure. If the machine detects a "flow limitation", it will also increase the pressure. A flow limitation is a flattening of the flow rate at its peak. In other words, instead of a rounded curve, it looks more like a square wave. That indicates that your airway is partially obstructed, limiting the total airflow, and probably signifying an apnea event is forthcoming.

So you can see that the machine can detect a forthcoming apnea event and raise the pressure to try to prevent it. However, if your pressure settings are too low, the raise in pressure might not be enough to prevent the apnea event, so it might look like the rise in pressure triggered the apnea event, whereas the opposite is true - it tried to prevent the event, but didn't act "vigorously" enough.

Looking at your flow rate graph, that looks very similar to mine when my pressure was set too low (eg. when I rolled onto my back). I will echo PaulaO2's (implicit) advice to not lower your minimum setting. If anything, it looks like it wants to be raised.

There was another recent tread discussing auto-CPAP pressure ranges which discussed the setting of the upper limit. I believe the consensus is that, as long as you can stand the pressure (ie. have gotten used to it), there is no reason not to set your upper limit to its maximum value (20 for your machine). If the machine decides that you need a higher pressure, there is typically no reason not to provide it. And the machine should not raise the pressure beyond what you actually need.

Don't worry about clear-airway events for now. Get your obstructive apnea under control. And, when looking at your data, make sure you ignore any events that happen while you are awake. It is easy to hold your breath while you shift positions, and since the machine doesn't know you are doing that consciously, it counts it as an apnea event.

Thanks Ron!

Great advice Ron and much appreciated! The current setting is 8-13. I will increase the top number but do most people also increase the bottom number or keep it the same at 8?

Thanks again in advance!

Monte

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#9
(07-14-2013, 06:09 PM)montehotbike12 Wrote: The current setting is 8-13. I will increase the top number but do most people also increase the bottom number or keep it the same at 8?
Any adjustment have to be for a valid reason. We might take a different approach but the goal is the same, get a good night sleep and wake up feeling bit better than the previous night .... sort of work in progress
If one have an issue with flow limitation, the machine ramp pressure in response to flow limitation until maximum reached or you wake up. Higher pressure than necessary may cause aerophagia, induce central apnea and more leaks, leaks disrupt sleep and lead to sleep fragmentation
Based on protocol, patience is the key to successful titartion ... wait - watch - observe - think




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#10
If it were me, I would be looking at the SleepyHead plots of the pressure to see what is going on. As I mentioned, increasing the upper limit shouldn't have any effect if you don't actually need that higher pressure. So if your pressure plots are always below your upper limit of 13, increasing that upper limit won't actually change anything. My guess, however, based on your flow rate plot, is that you are maxing out your pressure, at least on occasion.

You might want to consider increasing the upper limit only partway for the short term. If it turns out that you actually need a very high pressure (eg. 18 cmH2O), going there in one swoop might be somewhat uncomfortable for you. In addition to getting used to the additional pressure, you will probably find that you also need to adjust your mask straps. What was tight enough for a pressure of 8 will probably blow right off your face with a pressure of 18. So work up to it gradually.

As for the lower limit, this one is trickier. For this, you _really_ want to follow zonk's advice and only change it if there is a reason. Once again, look at your pressure plots. If you start at 8 but spend almost all of your time (say) at 10 and higher, then raising that lower limit to 10 would make sense.

Unless there is a clear indication that your lower limit pressure is too low, you might consider holding off on adjusting that until you have run a week or two with the higher upper limit pressure. One great thing about the lower limit pressure on an auto-CPAP machine is that it acts like a sleep-triggered ramp function. While you are still awake, you will tend to be breathing normally, so your machine will keep the pressure low (and comfortable). The ramp function increases the pressure linearly on a timed basis, regardless of whether you have fallen asleep or not. However, the auto-CPAP will only increase the pressure when obstructive apnea threatens, and that typically will only happen as you fall asleep.

Good luck, and Sleep-well
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