Will Flow Limitations caused by UARS Show Up in Oscar?

[Bijingus]

Wouldn't increased respiratory effort essentially increase pressure in your airway and keep the flow rate in your nostrils looking the same? I'm wondering because I'm trying to self titrate for UARS. I feel no better and see nothing in the OSCAR data to indicate flow limitations.

[robysue1]

Wouldn't increased respiratory effort essentially increase pressure in your airway and keep the flow rate in your nostrils looking the same? I'm wondering because I'm trying to self titrate for UARS. I feel no better and see nothing in the OSCAR data to indicate flow limitations.

What machine are you using? Some machines do attempt to score flow limitations, but the way flow limitations are scored depends on the brand of machine you are using.

Next, flow limitations are not so much about "increased pressure" in the airway. The increasing respiratory effort (as measured by the belts on a sleep test) is the result an unstable airway that can be thought of as in the very first stages of a potential collapse. The flow limitation is the result of the unstable airway: Not as much air is getting into the airway and the air that is getting into the airway is not smoothly and effortlessly being inhaled. This results in the inhalation part of the flow rate curve becoming distorted in its shape. You can only see the distortions in Oscar if you zoom in on the flow rate graph to the point where it is possible to see individual breaths.

Typically if you know what you're looking for, zooming in where you are seeing between 1 and 5 minutes worth of flow rate data is enough to spot stretches of breathing that have a high likelihood of being flow limitations that are related to an unstable airway that is in some danger of collapsing.

Here's a chart that illustrates some different inhalation shapes that are thought to be related to flow limitations:


If you want to learn a whole lot more about what flow limitations are and how they show up in the flow rate data, then reading the paper where that chart is pulled from is a reasonable idea. The paper is titled Frequency of flow limitation using airflow shape, and if you click on the link, it will take you to the paper.

[robysue1]

I'm wondering because I'm trying to self titrate for UARS. I feel no better and see nothing in the OSCAR data to indicate flow limitations.

1: How long have you been trying to self-titrate for UARS? And exactly what machine are you using? And what pressure or pressure range are you using?

2: Why do you think your sleep problems are related to UARS? In all seriousness, there are a lot of things that can cause bad sleep. Yes, sleep disordered breathing (ranging from snoring to UARS to OSA) is a major cause of bad sleep but it's not the only cause. And PAP therapy won't fix any sleep problem that is not directly related to some form of sleep disordered breathing.

3: What does your current sleep look like? How many hours are you sleeping with the machine each night? How many hours are you sleeping without using the machine? How long does it take you to get to sleep? And how many times do you remember waking up during the night?

4: What are your daytime symptoms? Excessive daytime sleepiness or excessive daytime fatigue? They're not the same thing.

[Bijingus]

Thanks for the info. I'll read the link you provided soon.

In my OSCAR data, based on the chart you shared, I could have some "possible" flow limitations. They don't quite look that exaggerated though. It won't let me attach screenshots. They're just PNGs under 100kb... I'll try again later.

I believe I have UARS because of two Watchpat studies which showed AHI of 10 and RDI of 32 and AHI of 20 and RDI of 40. Yes, the AHI is in the mild to moderate OSA range, but the RDI is much higher. I've also had two in lab PSGs which showed an AHI of 1 and they didn't score RDI. They dismissed the first Watchpat study as meaningless despite studies showing a very high correlation with PSGs. I'm leaning toward the Watchpat studies because they measure peripheral arterial tone and in in turn sympathetic nervous system activity. Most of the time I feel extremely stressed (despite a very not stressful life) and fatigued (not necessarily sleepy). 40 fight or flight responses every hour while sleeping seems to explain everything. I've also recorded myself sleeping several times and I don't hear choking or snoring, just labored breathing. I also move a lot. Initially I thought this was periodic limb movement disorder, but I think it's just my nervous system kicking in because I'm not getting enough air. I tried several meds for PLMD with no success. I also recorded my limb movements with an accelerometer at home and saw no difference in the movement data.

In terms of symptoms, I experience daily fatigue (sometimes sleepiness) ranging from mild to severe, headaches, brain fog, stress/anxiety (despite no stress and no anxious thoughts), cold hands/feet, mild hypertension (I'm only about 15 pounds overweight), chronically bad digestion, and I have to fall asleep on my stomach.

I'm using a Resmed Vauto 10 bilevel machine for about 5 weeks now. It's been a frustrating experience for several reasons. First, I tried the nasal mask and nasal pillows. For some reason it made breathing even more difficult. I then got a full face mask and breathing is fine. I tape my mouth most nights. I have no idea why this is and it makes no sense. Second, I've read everything I can find on self titration for UARS and the lack of info is maddening. Doctors like Krakow pretty much just say "keep fiddling until you feel better." Finally, when I look at the data in OSCAR, I get way too many treatment induced central apneas. Low pressure, high pressure, doesn't matter. Pressure support seems to make it worse and I actually prefer the feeling of CPAP. I don't like the feeling of the extra pressure on inhale.

I sleep about 8 hours a night and usually remember waking up two or three times. I'm usually asleep within about 5 minutes. If I do in fact have UARS I'm lucky to at least not have insomnia. It takes me 30 mins to an hour to fall asleep with CPAP though. With the new mask I've been able to keep the Resmed machine on for most of the night without waking up more than a couple times.

[robysue1]

Thanks for the info. I'll read the link you provided soon.

In my OSCAR data, based on the chart you shared, I could have some "possible" flow limitations. They don't quite look that exaggerated though. It won't let me attach screenshots. They're just PNGs under 100kb... I'll try again later.

The board's attachment area is full. Try uploading the pngs to a site like imgur and link to the images in your post. Better yet, copy the BBCode and paste that into your post and the image will show up.

In terms of symptoms, I experience daily fatigue (sometimes sleepiness) ranging from mild to severe, headaches, brain fog, stress/anxiety (despite no stress and no anxious thoughts), cold hands/feet, mild hypertension (I'm only about 15 pounds overweight), chronically bad digestion, and I have to fall asleep on my stomach.

When was the last time you had a full physical? Have you had a thyroid test recently? I ask because while sleep disordered breathing would account for a lot of this, so could a lot of non-sleep related problems.

I also move a lot. Initially I thought this was periodic limb movement disorder, but I think it's just my nervous system kicking in because I'm not getting enough air. I tried several meds for PLMD with no success.

I take it the in-lab PSGs were negative for PLMD. That correct?

I'm using a Resmed Vauto 10 bilevel machine for about 5 weeks now. It's been a frustrating experience for several reasons. First, I tried the nasal mask and nasal pillows. For some reason it made breathing even more difficult. I then got a full face mask and breathing is fine. I tape my mouth most nights. I have no idea why this is and it makes no sense.

I know you don't want to hear this, but ...

It could be that you just need more time. It sounds like you are not yet sleeping well with the machine. It can take some people several weeks to 2 or 3 months of sleeping well with the machine before they really start to notice a difference in how they feel during the daytime.

And it's not yet clear that you are sleeping well with the machine.

Finally, when I look at the data in OSCAR, I get way too many treatment induced central apneas. Low pressure, high pressure, doesn't matter. Pressure support seems to make it worse

How many centrals are we actually talking about?

Here are some things you need to keep in mind about CAs:

1) A few CAs scored during the night are not enough to be considered treatment induced central apnea. It's rather common (and normal) to have a CA or two during the transition to/from sleep, and on an in-lab sleep study they would not get scored due to the EEG data. But your AirCurve 10 VAuto is going to score them anyway.

2) If you are restless during the night and you are drifting in and out of sleep, your breathing can look much more like wake breathing or a mixture of wake and sleep breathing. We call this sleep-wake-junk breathing around here. And it's not uncommon for a lot of CAs to be scored during SWJ. But the thing is most (maybe all) of the CAs scored during SWJ breathing are likely not real CAs in the sense that they would be scored as CAs on an in lab PSG. They're normal sleep transitional CAs and the problem is more that you are stuck in SWJ rather than transitioning all the way to real sleep. That's usually not a result of under treated sleep disordered breathing; rather it's more indicative of a problem with sleep architecture and/or sleep maintenance problems, which can be really difficult to deal with.

3) Even if you are experiencing a whole lot of real treatment-induced CAs, the standard approach by many sleep doctors is a wait-and-watch approach: Many times the treatment-induced CAs will resolve themselves in about 6-8 weeks. So it's probably not yet time to worry about the number of CAs unless you are having a CAI > 5 (i.e. 35 or more CAs scored in 7 hours of usage) on the vast majority of your nights.

and I actually prefer the feeling of CPAP. I don't like the feeling of the extra pressure on inhale.

There's nothing particularly wrong with using a PS = 0. But often folks with UARS are told that additional PS may help smooth out the flow limitations, which appear to be the root cause of the respiratory related arousals in UARS.

Out of curiosity: When you say you don't like the feeling of extra pressure on inhalation, what exactly do you mean? What is it that you find disturbing or uncomfortable when the pressure goes up when you start to inhale? Do you feel like the machine is rushing you to inhale (increasing the pressure earlier than you want) or do you feel like you're inhaling and the pressure is still suck too low to comfortably inhale (increasing the pressure later than you want)?

The VAuto has a setting (Ti_Trigger) that control how soon the pressure starts to increase when you inhale. So you might want to check that setting.

I sleep about 8 hours a night and usually remember waking up two or three times. I'm usually asleep within about 5 minutes. If I do in fact have UARS I'm lucky to at least not have insomnia. It takes me 30 mins to an hour to fall asleep with CPAP though. With the new mask I've been able to keep the Resmed machine on for most of the night without waking up more than a couple times.

So with the machine you are taking about 30-60 minutes to fall asleep and you are waking up 1-3 times during the night. And you are in bed for 8 hours?

That means on a bad night, you might have as much as 75-90 minutes of WAKE during that 8 hour period, and you might actually be getting only 6.5-6.75 hours of actual sleep. (Not counting any remaining spontaneous arousals that you might still be having.). That's a sleep efficiency around 81-85%. Not terrible, but enough for some people to still feel less than well rested when they get up in the morning.

That 30-60 minute latency to sleep might be a bit problematic as well. When you are lying in bed with the mask on at the beginning of the night and you're finding it difficult to get to sleep, what's running through your mind?

Second, I've read everything I can find on self titration for UARS and the lack of info is maddening. Doctors like Krakow pretty much just say "keep fiddling until you feel better."

Well the problem is that UARS is not well understood; most sleep labs don't have the PES equipment really needed to measure real RERAs and the PES equipment makes the in-lab sleep test even more uncomfortable than usual.

So the question becomes: How are you trying to self-titrate for your suspected UARS problem?

You're using a Resmed AirCurve 10 VAuto. But ....

1) What mode(s) of operation have you tried? VAuto? S? CPAP?

2) What are the therapeutic settings that you've tried? How long have you stuck with any of the various settings that you've tried? Note: Therapeutic settings include min EPAP, max IPAP, and PS in VAuto mode. Also useful to know Ti_Trigger, Ti_Cycle, Ti_min, and Ti_max if you are using PS > 0 in VAuto mode or S mode.

3) What does your flow limitation graph look like on a typical night? What about the snore graph?

4) If you use VAuto mode, what are the median and 95% EPAP and IPAP pressure levels like? If you've used more than one set of min EPAP/max IPAP settings, how does this data change when you increase the min EPAP and/or increase the max IPAP setting?

5) What does your leak data and your leak graph look like on a typical night?

And finally: Since your Resmed AirCurve Vauto does not attempt to measure RERAs, the AHI data may very well be quite low while you are still having issues with UARS at night. That's why doctors like Krakow pretty much just say "keep fiddling until you feel better"---there's no concrete piece of data (like the AHI) to look at when the problem is UARS and RERAs instead of OSA and OAs/Hs. But measuring how well you feel can seem damn difficult. When you're faced with measuring success based on subjective data (i.e. "how you feel"), you can't expect the machine's data to give you as much insight as you want. At least not all by itself. But the machine data combined with some decent quality subjective data can help you sort things out.

I would suggest that you consider keeping a sleep log that might help you tease out whether the machine is doing some good and if it's doing some good, exactly what that "good" is. Your sleep log should have the following data recorded for each night and you should fill in most of the sleep log after waking up each morning:

• Recap of how you felt during the day. I'd suggest using a simple 0-5 rating to start with. Maybe make a few comments if you feel particularly good or bad during the day.
• Time you go to bed (record this at bedtime or use the CPAP's time stamp for when you turned it on.)
• Time you woke up in the morning. Ideally this should be when you get out of bed.
• Estimated time to get to sleep. Do not look at the clock. And don't worry about accuracy. You just want to record your impression (in the morning) of how long it took you to get to sleep at night. Something simple like 10-15 minutes is fine.
• Estimated number of wakes that you remember during the night. Do NOT try to keep yourself awake each time you wake up during the night. Again the idea is to capture your impression of the night. If you remember "2 or 3 wakes", you don't need to try to figure out whether it was 2 wakes or 3 wakes.
• Estimated time you were awake during the night after first getting to sleep. Do NOT use a clock to determine this. You just want your impression of how much time you were awake. As a general rule, if you don't remember any serious trouble getting back to sleep after any of the wakes, you can assume that each wake was probably about 5 minutes long.
• Rate how you feel immediately on waking. I'd suggest using a simple 0-5 rating to start with. If something clearly feels "bad", make a note of it. Or if you feel particularly good, make a note of that.

Don't try to overanalyze the sleep log every day. But at the end of the week sit down and look at the log data and the CPAP data together. You're trying to tease out whether there's any pattern to the days you feel somewhat better as compared to the days where you feel somewhat worse. And you have to be open-minded about what kinds of patterns might emerge from the sleep log.

In my own case, a sleep log was critical for me to identify that as I finally started sleeping half-way decently with the machine, I also started waking up with little or no hand and foot pain on many mornings. I had been waking up with hand & foot pain for years before my OSA diagnosis; I would tell my husband that it felt like I'd slept with my hands and feet in fists all night long. I now believe all of my "hypopneas with arousal" were in fact triggering flight or fight responses in my body and that my hands and feet were, in fact, tensing up for most of the night. When all those respiratory-related arousals were no longer happening AND I was actually getting some real, honest sleep with my BiPAP, that pain started to disappear. But the change was gradual enough that I'm not sure I would have noticed it if I hadn't been writing "Woke up with no hand/foot pain" several times a week in my sleep log.