CA longer than 1 minute?

[ohwhatanight]

BTW - Can anyone comment on my snoring? I have between 130-180 vibratory snore "events" per night ranging up to 40. I am still within my first 30 day period, so my doctor probably wouldn't think too highly of me changing my pressure on my own. I am on 8 which seems pretty low but my AHI is only around 1.0 so it seems to be working okay except for the snoring. But is there anything else I can do? I quit using the ramp after the first couple of nights. Will adjusting the CFlex make a difference? I have it set on 2 now. If so, should it go up or down?

I don't seem to be snoring out of my mouth since my mouth isn't dry at all in the morning (it used to be all the time before CPAP).

[Pugsy]

BTW - Can anyone comment on my snoring?

Snores are by definition minor flow reductions. Usually resolved with a wee bit more pressure but I understand your reluctance to mess with the settings so early in therapy.
Not much you can do except perhaps experiment to see if there is a strong positional component like being worse sleeping on your back..try staying on your side as much as you can if that is possible. If you are already staying on your side all the time, not much else you can try.

CFlex setting is unlikely to cause enough of a reduction in pressure to impact the snores but if you are up to it you might try a reduction in the setting. Respironics Flex settings don't cause a marked reduction in pressure like the ResMed machines do. Instead the Flex function does a flow based small reduction for a shorter duration and we just don't see that much of a pressure change. Though you could certainly try the different settings to see if it helps at all.
Turning off might be an option since a pressure of 8 cm is really rather mild.
Turning off Flex doesn't always equal less of any type of events though. I turned AFlex off once and had a horrible night with a huge increase in events compared to when I used AFlex.
But everyone can and will respond differently so it wouldn't hurt to try.

[Otter]

I'm not familiar with the way your machine reports snoring. It certainly looks like you're snoring a lot, but without knowledge of the units in that graph, I can't really say.

If I thought I was snoring excessively, I'd bump the pressure, but I've always been self-titrated. If I'd had a sleep study and my doctor was more involved in my treatment, I'd probably call her before making the change. But if I really thought my therapy wasn't as effective as it could be, I wouldn't wait for someone else to take the initiative. I don't see that there is anything to be gained therapeutically or diagnostically by sawing away until your next appointment. Why wait?

Pugsy has a good point about your sleeping position. Odds are good that most of that snoring is happening when you're on your back. But you've got your AHI down pretty low with only 8cm h2o, so I'm not sure it's worth the hassle to try to stay off your back. I think it will be less disturbing to your sleep to just raise the pressure.

[archangle]

... What do you mean by "wake you up?" Are you expecting some kind of alarm? ...

Actually, that is a feature of most machines that treat central apneas.

BiPAP S/T and ASV units all have an alarm to handle long apneas.

Most BiPAP and CPAP units do NOT have this feature.

Thanks, that's news to me. Is the alarm loud enough to wake you up? My PRS1 "mask leak" alarm is way to quiet to do much good. If not breathing doesn't wake you up, it seems like it's going to take a loud alarm to do the job.

That could actually be a neat optional feature to add to CPAP and bilevel devices.

[archangle]

To me, the big clue is the really big "inhale" hump before the alleged apnea. Plus the "leak" line, but the leak line is delayed because it's an average reading.

Try an experiment and turn on your CPAP, breathe a while, then disconnect the hose from the mask and let it blow for a minute or so, then plug the end of the hose with your thumb for a minute or so. Repeat a few times, then look at the waveform.

It's also informative to do the same thing by lifting up the edge of the mask and making a relatively large leak while still wearing the mask and breathing normally.

Studying these waveforms will help you figure out how to interpret waveforms.

This also shows you why it's so important to record airflow waveforms and learn how to read them. With a machine that doesn't record waveforms, you wouldn't be able to tell this wasn't a real apnea.

[ohwhatanight]

To me, the big clue is the really big "inhale" hump before the alleged apnea. Plus the "leak" line, but the leak line is delayed because it's an average reading.

Try an experiment and turn on your CPAP, breathe a while, then disconnect the hose from the mask and let it blow for a minute or so, then plug the end of the hose with your thumb for a minute or so. Repeat a few times, then look at the waveform.

It's also informative to do the same thing by lifting up the edge of the mask and making a relatively large leak while still wearing the mask and breathing normally.

Studying these waveforms will help you figure out how to interpret waveforms.

This also shows you why it's so important to record airflow waveforms and learn how to read them. With a machine that doesn't record waveforms, you wouldn't be able to tell this wasn't a real apnea.

Thanks for the experiment! I will try this tonight while I am still awake.

I am a side sleeper, almost exclusively on my right side. During my sleep studies, I slept on my side the whole time (some on my left) and they also reported heavy snoring both nights (including the night with the CPAP). I asked my doc about it, but she said she didn't have any snore data from my machine from the DME. (??) So, should I print off my SleepHead data and take to her or is that a really really bad idea? (I don't want to p**s off the sleep doc!) When I saw her just a few days after I got my CPAP, it was for less than 5 minutes and was the basic "you are doing great, lose weight, see you in a year" kind of appointment. Or is this something I should bring up with the DME since they see my data (supposedly - I have a modem on my machine right now.) I could always take in my SD card too, I assume.

[idamtnboy]

To me, the big clue is the really big "inhale" hump before the alleged apnea. Plus the "leak" line, but the leak line is delayed because it's an average reading.

Big clue meaning what? I just looked at my graphs for the past few weeks. More often than not I have a similar large inhale hump just before the CA.

[Otter]

I am a side sleeper, almost exclusively on my right side. During my sleep studies, I slept on my side the whole time (some on my left) and they also reported heavy snoring both nights (including the night with the CPAP). I asked my doc about it, but she said she didn't have any snore data from my machine from the DME. (??) So, should I print off my SleepHead data and take to her or is that a really really bad idea? (I don't want to p**s off the sleep doc!)

If she's pissed off about that, don't worry about it. Just go home and start shopping for a new sleep doc. Any doctor who would be upset about that you are taking an active interest in your own health is one you should replace ASAP.

When I saw her just a few days after I got my CPAP, it was for less than 5 minutes and was the basic "you are doing great, lose weight, see you in a year" kind of appointment. Or is this something I should bring up with the DME since they see my data (supposedly - I have a modem on my machine right now.)

This depends on the DME. Most either wouldn't care or would be afraid of stepping on your doctor's toes. Legally, they can't diagnose you, and from what I've seen, most probably don't have the knowledge to help you interpret your data anyway. But some RT's might discuss this sort of thing with you. It won't hurt to ask, just don't expect much. The most common reaction form DME's seems to be, "Egads! How did you get into your data? You're not allowed to see that!"

[archangle]

To me, the big clue is the really big "inhale" hump before the alleged apnea. Plus the "leak" line, but the leak line is delayed because it's an average reading.

Big clue meaning what? I just looked at my graphs for the past few weeks. More often than not I have a similar large inhale hump just before the CA.

Post one of the suspicious graphs. Be sure to include leak rate and some time before and after the event.

The big hump is a clue that it may be the start of a large leak.

This gets into the black art of reading graphs and understanding what the machine actually records. The machine attempts to subtract out the leaks from the waveform data. It can't really see the leak rate, so it averages the airflow over a period of time and subtracts it.

If you develop a large leak or take the mask off, the recorded airflow rate will shoot up, but the graph will drop back to zero because the machine will subtract the leak out. It makes more sense if you do the experiment with the hose and look at the results. You'll see a hump that looks a bit like that.

Once you have your mouth open enough or have a large enough mask leak, you're breathing a some of your air from the outside, not through the CPAP machine. Even if you're breathing normally, it will show up as a reduced amount of breathing from the machine.

Another way to think about it is to imagine you take your mask off, leave the machine on, and continue breathing. The machine would see no breathing. Its clear airway detection techniques will not see any blockage, so it will call it a clear airway/central apnea. (The machine may actually be smart enough to figure it out if you completely take the mask off.)

This doesn't mean you should simply ignore CA indications. However, check your leak readings and learn to read the graph, and you may figure out that some of the apnea readings are bogus.

Remember that if your CPAP is recording false apneas due to leaks, you do still need to fix your leaks.

[idamtnboy]

The big hump is a clue that it may be the start of a large leak.
.......
If you develop a large leak or take the mask off, the recorded airflow rate will shoot up, but the graph will drop back to zero because the machine will subtract the leak out. It makes more sense if you do the experiment with the hose and look at the results. You'll see a hump that looks a bit like that.

Once you have your mouth open enough or have a large enough mask leak, you're breathing a some of your air from the outside, not through the CPAP machine. Even if you're breathing normally, it will show up as a reduced amount of breathing from the machine.

Another way to think about it is to imagine you take your mask off, leave the machine on, and continue breathing. The machine would see no breathing. Its clear airway detection techniques will not see any blockage, so it will call it a clear airway/central apnea. (The machine may actually be smart enough to figure it out if you completely take the mask off.)

This doesn't mean you should simply ignore CA indications. However, check your leak readings and learn to read the graph, and you may figure out that some of the apnea readings are bogus.

Remember that if your CPAP is recording false apneas due to leaks, you do still need to fix your leaks.

I think you're giving leaks more credit than they deserve. All the CAs of mine I mention above occurred during steady state sleep phase. I just looked at one night's graph and the leak line was flat at zero during the entire time span of 3 events, including before and after. If the mask is leaking you still get all your breathing air from the PAP. If the leak is severe the machine can still see the apnea. I show that in the graph in this thread: viewtopic.php?f=1&t=74709&p=685033&hilit=+leak#p685033. The S9 won't distinguish between OA and CA at high leak rates and calls them unknown.

The machine doesn't subtract a varying leak value. There's a fixed leak value put into the operating parameters to reflect the mask vent rate. That stays constant so when the graph takes a jump up, it's because the flow took a jump up. And then when the graph drops back to zero it's because the flow dropped back to zero, not because of a change in the subtraction value.

I don't know about the PR1 but the S9 samples the flow at 25 Hz. That's plenty often enough to compensate plenty quick to leak changes, so I don't think your scenario of the PAP getting confused by leaks is plausible. I just looked at one CA where leak took a jump. The flow just before the CA jumped to a max of about 50 L/min but the leak only went up about 2 L/min.

I believe the OP really did have a CA of about 1 min length and the graph was not distorted by a leak.

[archangle]

The machine doesn't subtract a varying leak value.

I'm talking about the flow rate graph, not the leak graph.

Both the PRS1 and S9 subtract a running average of the current leak rate from the flow rate graph in order to keep the inhale and exhale centered around zero. If they didn't do this, your flow rate graph would drift up and down as you develop leaks.

I can show you this on the graphs if further explanation is necessary.

I believe the OP really did have a CA of about 1 min length and the graph was not distorted by a leak.

Note that her tidal volume reading went from 300 or so to 5500. Either that hump is a big leak, or she took a really, really deep breath. I'm a full grown male adult and my tidal volume is about 400.

Here's an image of what it looks like when I lifted up the edge of my mask to cause a large leak while still breathing. Note the hump to start, followed by the very small breathing pattern on the flow rate waveform. Also note the very high tidal volume number. I was breathing normally throughout the whole time of the graph.



My machine flagged a hypopnea on this event, but on some earlier attempts, it flagged a CA. There were no real hypopneas or CAs while I was doing this, just leak induced artifacts.

[JohnBFisher]

... Thanks, that's news to me. Is the alarm loud enough to wake you up? My PRS1 "mask leak" alarm is way to quiet to do much good. If not breathing doesn't wake you up, it seems like it's going to take a loud alarm to do the job. ... That could actually be a neat optional feature to add to CPAP and bilevel devices. ...

Yup. Though the alarm volume can be set (up or down), even the quiet level is loud enough to "wake the dead". I frankly turn off the alarms because the ASV unit does a good job of helping me through my long central apneas. Mine tend to come during deep NREM stages of sleep and not during REM sleep (the increased neural activity during REM sleep increases the respiratory drive). So, they are not too frequent or too long - most of the time. Every now and then I awaken with a morning headache, but that's pretty rare since I started to use my ASV unit.

But if someone had real problems with it, the alarm can be a big help - if somewhat annoying! 8^)

[ohwhatanight]

I've tried the suggested experiments briefly to try to recreate this, but so far causing a leak gives me a large tidal volume reading but not an apnea event or flattened flow rate or drop in resp. rate. Holding my breath does recreate the graphs much closer to the one I posted earlier (though I can only hold it for about 15 seconds) with a spike in tidal volume. I was able to get it to record a fake OA. I noticed on my earlier charts - one the first page of this thread - there is another smaller spike in tidal volume corresponding to another sudden drop in respiratory rate and back to back H & OA that span about 30 seconds total at approx. 4:10 with no big leak around that time.

So, I am still baffled and still not sure whether or not this was real or not. Guess I won't know unless it repeats itself, which I hope it never does!

Probably unrelated but can't be totally sure - I've had mild but persistent upper chest pain the past couple of days. If it isn't better by the morning, I will go get it checked out. It's in a weird place - way high on my chest between and including my shoulders but equally on both sides. Could be a upper respiratory infection. Hoping it isn't a cardiac kind of thing. If it is an URI, could that explain the weird "event"?

[idamtnboy]

Both the PRS1 and S9 subtract a running average of the current leak rate from the flow rate graph in order to keep the inhale and exhale centered around zero. If they didn't do this, your flow rate graph would drift up and down as you develop leaks.

I can show you this on the graphs if further explanation is necessary.

Note that her tidal volume reading went from 300 or so to 5500. Either that hump is a big leak, or she took a really, really deep breath. I'm a full grown male adult and my tidal volume is about 400.

Here's an image of what it looks like when I lifted up the edge of my mask to cause a large leak while still breathing. Note the hump to start, followed by the very small breathing pattern on the flow rate waveform. Also note the very high tidal volume number. I was breathing normally throughout the whole time of the graph.

I see now what you mean. You make a good point.

[archangle]

Experiment a little longer and you'll probably get something similar. Experiment with trying to make various slow leaks, larger leaks, pulling it off slowly or quickly, and disconnecting the mask entirely. Since you have small bumps from later breaths, you must still be at least partly connected to the mask.

Stop and think about what the graph shows. If it's not a leak artifact, anything above the zero line is an inhale, and below is an exhale. The area between zero and the curve is the amount of air you're inhaling or exhaling in one breath.

If it's not an artifact, at 5:21, you inhaled an enormous volume of air. (5500 mL, roughly 10 times your normal lungfull). Then the airflow line never drops below zero indicating an exhale. You would have had to have filled your lungs with a really big inhale, and then held it for about a minute. Since it's flagged as a central apnea, you would have to have held it without closing off your airway. Try sucking in a really deep breath and holding it without closing off your airway.

Does anyone with "real" central apnea have a graph of a "real" event? Do you ever start a CA with your lungs full, or does it happen after your relax on exhale?