(11-01-2016, 12:42 PM)mcsheltie Wrote: At some point I'll stop posting so much (I hope!) There is just so much to learn. And a lot of it makes no sense to me!
Why are there two lines on the Leak Rate chart?
You are using a PR machine. The leak data that the machine records is the
Total Leak Rate which includes both the
intentional mask leak designed to prevent your rebreathing CO2.
In SleepyHead, the
top graph in the Leak Rate chart is the graph of the Total Leak Rate data. Any official Large Leak flags are based on the Total Leak Rate data, but PR does not tell us exactly what criteria are used to determine when the leaks are high enough to be considered an official Large Leak.
The
bottom graph in the SleepyHead Leak Rate chart is Sleepy Head's
estimate of your
Unintentional Leak Rate. The Unintentional Leak is the "bad" kind of leaking---this is any leak that is over and above the intentional mask leak for the mask you use and the pressure you use.
If you go into the SleepyHead Preferences and click the CPAP tab, there is a spot on the left side of the window that says
Calculate Unintentional Leaks When Not Present. If the box in front of this is
checked, SH estimates the unintentional leak rate. The box is checked by default. Underneath the line that reads
Calculate Unintentional Leaks When Not Present there are two slider bars, one marked 4cm and one marked 20cm. You should compare the values where the slider on each of these bars to the Intentional Leak Rate chart that should be included in the user manual for your mask. The default values are some kind of averages for a whole bunch of nasal and nasal pillows masks as I recall. If you use a full face mask, you really need to look at those numbers and make sure they're set correctly so that SH can accurately estimate your Unintentional Leak Rate.
Quote:From 1:40:05 to 1:40:15 it looks to me like I wasn't breathing. Why isn't this time period flagged?
In eyeballing it, it looks like this event may have barely missed the 10 second rule. The scoring algorithms are good, but they're not infallible. Sometimes they miss events. Sometimes they score an event that should not be scored. In the grand scheme of things, it kind of evens out in the end.
You can, however, set up "user flags" in SH to flag things like this.
How much you should worry about them is another thing. In general if these "almost" apneas are not very many and are not tightly clustered together, they may not be worth worrying to much about.
Quote:What is a pressure pulse? There were five of them last night.
When the PR DreamStation thinks it MIGHT need to score an apnea, it sends out a so-called "pressure pulse" or PP for short. The PP is a very short, brief "puff" of additional pressure. The machine measures how the PP affects the back pressure (the pressure at the machine end of the hose) and uses that information to decide whether your airway is obviously obstructed or is probably clear (not obstructed). If the not breathing continues on long enough to be scored as an apnea, its the PP that determines whether the machine scores an OA or a CA. If the event is quite long OR if the results from the first PP are ambiguous, the machine may send out more than one PP in a particular apnea.
The machine will also use a series of PPs if it no longer detects breathing, particularly when there is a relatively large leak.
Outside of the fact that the machine uses PPs to classify the kind of apnea, there's no clinical significance to the PPs.
Quote:Why is this flagged as an RERA? It doesn't look any different to me than what occurred before and after.
This is an example where the machine has erred on the side of "flagging" something as an event might not be a real event. There are no recovery breaths in the snippet of breathing that you showed. It's possible that the recovery breaths are after 4:51:20 mark. Or it's possible this is just an outright mistake in labeling what's going on. It's also worth pointing out that the placement of the RERA flags is "fragile" in the sense that the flag is often not right at the end of the event.
It is surprising to me that the machine did NOT label some flow limitations here. These inhalations look flow limited in my opinion, and it really is a bit surprising that the machine chose to label this as RERA instead of a FL. However, the fact that it labeled this stretch of breathing as a RERA does explain why it's not labeled as a FL.
In the hierarchy of labeling:
- A FL only needs distorted inhalations. How distorted and how long the distorted inhalations have to last are not documented in the information that is readily available about the PR's algorithms
- A RERA requires a sequence of flow limited breaths typically followed by one or more "recovery breaths". The recovery breaths are missing here, and it's not clear why the machine scored this as a RERA.
- An H requires the flow rate into/out of the lungs to be reduced by 50-80% from the running baseline AND the reduced airflow must last at least 10 seconds. The running baseline is calculated over the course of the last 5-10 minutes of breathing as I recall.
- An OA requires the flow rate to be reduced by at least 80% from the running baseline AND the reduced airflow must last at least 10 seconds AND the PP test must show there is a high probability that the airway is obstructed during the event.
- A CA requires the flow rate to be reduced by at least 80% from the running baseline AND the reduced airflow must last at least 10 seconds AND the PP test must show there is a high probability that the airway is clear (unobstructed) during the event.
There are numerous scenarios where a given stretch of breathing can be somewhat ambiguous when we look at the flow rate data.
Quote:I turned CFlex and AFlex off. Neither seems to sync with my breathing.
They are comfort features and if they bug you, it's best to just turn them off.
Quote:Both of the OAs woke me up.
Why do you think the OAs woke you up? And how many times do you think you woke up?
There is some evidence that the hypopnea scored around 23:30 woke you up---even at this scale, you can see evidence of "recovery breaths" right after that event. Recovery breaths can indicate an awakening or an arousal. The OA scored at 23:21 looks more like it might be a sleep transition event---the breathing settles down right
after that event is over as compared to the breathing before that event.
You may have awoken very briefly after the OA scored just before 5:00---there are some recovery breaths there and the breathing doesn't settle down afterwords. Were you restless for a long time between a wake around 5:00AM and 6:25 when you finally turned the machine off and back on?
If you really want to track when the wakes are so that you can try to figure out whether a particular event or event cluster is the culprit, you can try turning the machine off and back on any time you find yourself awake enough to know that you are awake in the middle of the night.
Quote:Mask leaks are driving me crazy. I've given this mask five days. I wake up constantly and move around all night. Now I have to add mask-fixing to all of that. I have learned a quick way to do it, but every time I rollover I have to make a conscious effort to stop a leak. And that makes it that much harder to get back to sleep.
It may be time to say goodbye to this mask and try another one.
What are the
best features of this mask---the ones you'd like to keep in the next mask you try?
Other than nasty problems with leaks, what are the
worst features of this mask?
Also, what are you doing for hose management?
Some people find hanging the hose helps with both minimizing leaks AND in increasing the ease of rolling over. If you've not tried hanging the hose, that's worth doing.
If you already ARE hanging the hose, it may be time to try something like running the hose under the covers and holding onto it at night. That way you don't have to fumble to find the hose when you turn over---it's already in your hands. And if you can better manage the hose when turning over, it's less likely to pull the mask off your face triggering a leak that must be fixed.
Quote:The night before I took a sleeping pill, I was just so sick of waking up all the time I needed one night of relief. Because I wasn't fixing it every time I moved, the leak rate was really high. The mask is comfortable and it doesn't leak at all if I could sleep on my back all night. But that would cripple me. As soon as I turn on my side it leaks under my nose, out the side or sometimes in my eye.
What was your favorite sleeping position before starting CPAP? If you were a side sleeper, which side? Right or Left? And which side are you on if you lie down in bed on your side and you are facing the CPAP?
All of that information may help us help you figure out a comfortable sleeping position for you.
Quote:Any advice on what to try next? Whatever it is, it needs to stay put as I roll around all night.
Have you tried a CPAP-pillow that has cutouts for the mask to hang into when you are sleeping on your side?
You might also want to try sleeping with your head at the very edge of the pillow so the mask can hang over the edge when you are sleeping on your side.