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Beginner's Guide to SleepyHead

64 bytes added, 21:58, 9 November 2015
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2) Remember to properly unmount the SD card from your computer before removing it from the SD slot or card reader. You unmount the SD card the same way you unmount a flash drive or an SD card from a digital camera.
3) Remember to put the card back into your PAP CPAP machine. This is particularly true for ResMed users: All the detailed data is written directly to the SD card, and if there is no SD card, that data is lost. And SH will report that there is no data for the night. (ResScan will be able to report on the summary data that is stored in the S9's memory and then written to the card when it is inserted into the machine).
= Basic SleepyHead Organization =
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The single most important piece of numerical data is the AHI data. The goal of PAP CPAP therapy is to keep the AHI down below 5 night after night.
If your AHI looks good and your leak data is acceptable, then the PAP CPAP machine is doing its job. Whether that's enough to make you feel great is another issue, but the machine '''is''' doing its job.
Under the AHI banner we see the indices for all the various types of "events" that might be recorded during the night. In other words, the line that says
'''NEW in SleepyHead 0.9.6: Time over leak redline'''
For ResMed S9 users, SleepyHead 0.9.6 will report the percentage of time when the Leaks are over the ResMed RedLine at 24 L/min at the end of the Statistical data under the Pie Chart. This should make it easier for ResMed S9 users to figure out whether their leaks are are significant enough to adversely affect therapy. Users of other PAP CPAP machines will not have this line in their Daily Data report.
'''Part I: Are my leaks bad enough to worry about?
If you use a PR System One or a ResMed S9, SleepyHead will show you the percentage of time your leaks were in Large Leak territory for your machine. This will help you evaluate whether or not your excess leaks are both large enough and long enough to adversely affect your therapy. A small amount of time in Large Leak territory can be ignored if your leaks are under control for most of the night; a large amount of time in Large Leak territory cannot be ignored.
The question is: How much time in Large Leak territory is too much? ResMed provides a guideline for its users: Mr. Red Frowny face shows up on the Sleep Quality Report if your leaks are above the Redline for at least 30% of the night. When the Large Leaks last that long, ResMed's engineers believe both efficacy of the PAP CPAP therapy and the accuracy of the recorded data can be adversely affected. We will assume that 30% of the night in Large Leak territory is clearly bad news for users of any PAP CPAP machine. But many people may find that their therapy begins to be compromised by the time Large Leaks make up 20% of the night. For a lot more information on leaks, see [http://www.apneaboard.com/wiki/index.php?title=Beginner%27s_Guide_to_SleepyHead#Leaks 8. Leaks].
If you are using a DeVilbiss IntelliPAP or an Fisher & Paykel Icon or if you are using SleepyHead 0.9.3 or earlier, then you will need to use the median and 90% (or 95%) Leak/Total Leak data to evaluate your leaks.
'''The Flow Rate graph'''
'''NOTE:''' ''ResMed S9, PR System One, and F&P Icon machines record Flow Rate data if the card is in the PAP CPAP machine during the night; the DeVilbiss IntelliPAP does NOT record Flow Rate data.''
The Flow Rate graph is also referred to as the "wave flow" graph. It provides a record of each and every breath you took all night long. At this scale, everything is all run together; the real power in the Flow Rate graph is when you zoom in sufficiently close to start seeing individual breaths and events. Note that each of the events in the event table shows up as a tick mark on the Flow Rate graph (with the exception of the PR System One VS2 tick marks.) The little boxes appearing on the sample patient's Flow Rate graph are mostly Pressure Pulses that the PR central detection algorithm uses for testing the patency of the airway.
The Pressure graph shows the therapeutic pressure level throughout the night. Because this particular patient uses a PR BiPAP, the IPAP and EPAP graphs vary independently of each other. The IPAP is the top graph; the EPAP is the lower graph. ResMed Elite and AutoSet users will have two pressure graphs if they have EPR turned on. The top graph is the Pressure setting; the bottom graph, which is label EPAP, shows what EPAP = Pressure - EPR looks like.
If you are using your PAP CPAP in fixed pressure mode, the pressure graph is not of much use---unless you are spending a lot of time hitting the ramp button. But if you are using your PAP CPAP in Auto mode, the pressure curve tells you when the machine raised the pressure and how much it raised the pressure. Comparing the pressure increases with the events flagged in the Flow Rate curve or the Events Table can give you some very good ideas about why the machine decided to increase the pressure and also give you a sense of whether the disordered breathing got better or worse with the pressure increase.
If you use a CPAP or APAP that is NOT a ResMed S9 Elite or S9 AutoSet, you will only see one pressure curve. If you use a bi-level device OR a ResMed S9 Elite or S9 AutoSet, you will see two curves. The top curve is the IPAP---the pressure setting for inhalations; the bottom curve is the EPAP---the pressure setting for exhalations. (The reason the S9 Elite and AutoSet have two pressure curves is that when EPR is on, the machine acts very much like a bi-level.)
If you are using your PAP CPAP in '''fixed pressure mode''', the Pressure graph will be a flat line after the ramp period is over. Hence the Pressure graph provides no useful data and can be ignored. So for this section, we will presume that you are using an auto adjusting machine and that it set to Auto mode.
The primary data you can get off the pressure curve is information about what the machine thinks your pressure needs seem to be for the night. Looking at the Pressure graph and the Flow Graph together allows you to see just how the machine responds to your sleep apnea each and every night. (On a ResMed S9 AutoSet, you might also need to look at the Snore graph and the Flow limitation graph as well.)
ResMed machines report only the excess leak rate, which is simply called '''Leak''' in the SleepyHead leak data. A ResMed user will see only one leak graph in the Leak Rate graph.
All other major brands of data-capable PAPs CPAPs report ''Total Leaks'', which include both the intentional leak rate for your mask at your pressure AND the excess leaks. In other words:
''Total Leak = Intentional Leak + Excess Leak''
'''Great, Good, and Decent Enough Leak/Total Leak lines'''
In general, a Great Total Leak line will be flat or almost flat and hover somewhere around (or just below) the intentional leak rate for your mask at your pressure. A Good Total Leak line will be "fuzzy" flat, stay mostly around the intentional leak rate for your mask and pressure, but tends to have some visible periods of noticeably higher leaks, most of which stay well below the cut off for "Large Leaks" for the given machine. A Decent Enough Total Leak line has more obvious leaks than a "Good" one does, but line stays below the Large Leak line for at least 70-90% of the night. (There's some debate between PAP CPAP users of just how long the Large Leaks need to last before they become problematic.)
For ResMed users or for folks who simply want to concentrate on the (excessive) Leak data, a Great Leak line will be flat or almost flat and hover somewhere around (or just below) 0.0 L/min. A Good Leak line will be "fuzzy" flat, stay mostly around 0.0 L/min, but tends to have some visible periods of noticeably higher leaks, most of which stay below 10-15 L/min. A Decent Enough Leak line has more obvious leaks than a "Good" one does, but the line stays below 25-30 L/min for at least 80-90% of the night. (There's some debate between PAP CPAP users of just how long the Large Leaks need to last before they become problematic.)
If we look at the Statistical Leak data from the Left Side bar for Great Leak/Total Leak lines and Good Leak/Total Leak lines, the 90% (or 95%) Leak/Total numbers will be under the manufacturer's definition of "Large Leak". The maximum may or may not be under that line.
These are leak lines where it's clear that Large Leaks are present during a significant amount of the night, but it's not clear if the Large Leaks last long enough for the machine's manufacturer to say they are a problem.
The manufacturer with the clearest definition of when Large Leaks become long enough to adversely affect the quality of the PAP CPAP therapy and the accuracy of the data is ResMed: ResMed's infamous ''Mr. Red Frowny Face'' shows up on the machine's Sleep Quality Report when the (excess) Leaks are AT or ABOVE 24 L/min for at least 30% of the night. So we'll assume that if the time in Large Leak is approaching 30% of the entire night, the Large Leaks are problematic.
So a good working notion for a Problematic Leak/Total Leak line would be the following:
'''Bad and Horrible Leak/Total Leak Lines'''
These are leak lines where it's clear that that Large Leaks are present during substantial amount of the night, and it's clear the Large Leaks are both '''long enough''' and '''large enough''' to adversely affect your PAP CPAP therapy.
A working definition of a Bad Leak/Total Leak line is that the leaks are bad enough to trigger a visit from ''Mr. Red Frowny Face'' if you were using a ResMed S9: If large leaks make up more than 30% of night, you've got a problem with leaks.
The Statistical Leak data for a Bad Leak/Total Leak lines may have a median Leak/Total Leak number well below the the manufacturer's definition of "Large Leak", but the 90% (or 95%) leak numbers, will be larger than the official Large Leak definition. If the median Leak/Total Leak number is close to or above the the manufacturer's definition of "Large Leak", then you've got a Horrible Leak/Total Leak line.
Most people don't have random, rare Bad or Horrible Leak/Total Leak lines. Folks who have real leak problems tend to have Bad or Horrible Leak lines on a significant portion of the the nights they use the PAPCPAP. If you are seeing multiple Bad or Horrible Leak/Total Leak lines each week, you know you need to do something about the leaks.
'''A final comment on the connection between the Statistical Leak data and the graphical leak data'''
And yet, many newbies are very interested in this graph. So in the interest of trying to clear up misconceptions about this graph, it is included here.
The y-value in the AHI graph gives running count of the number of apneas scored during the last 60 minutes of the current PAP CPAP session. In other words, the y-value of the SH AHI graph at time t is the total number of events (OAs+CAs+Hs) recorded during the last hour of run time in the current session. When a particular event becomes one hour old, it is dropped from the running total. Because each event that is scored remains part of the AHI graph until it is an hour old, the AHI graph will remain above 0.0 for long periods of time when no events are being scored. The following image shows a series of 3 events scored within an 8-minute period, followed by over an hour of sleep with no additional OAs, Hs, or CAs scored. The AHI first increases to 3 and it stays at 3 until each of the three events "ages" out of the running total:<br />
[[File:ahi-graph-balanced_zpsa8d453f9.jpg]]
At 6:28:14, the machine records OA3, and so the AHI graph goes from 2 back up to 3. The machine records H1 at 6:30:39, and the AHI graph goes from 3 to 4 at this point. The machine records H2 at 6:35:09, and the AHI graph increases from 4 to 5. The patient wakes up shortly after H2 and turns her BiPAP OFF at 6:36:15. It's the turning the BiPAP off at 6:36:15 that causes the AHI graph to suddenly plummet from 5 to 0.
'''Note''': Any time the PAP CPAP machine is turned OFF and then back ON, the AHI graph is reset to 0 because a new session has started.
'''Note to only ResScan users:''' The AHI graph in ResScan resets to 0 at the top of every hour. Hence it is not going to look like the default SleepyHead AHI graph. If you want the SH AHI graph to look like ResScan's, you can use the "Zero Reset" option for the AHI/Hour graph in the SH Preferences. See [http://www.apneaboard.com/wiki/index.php?title=Beginner%27s_Guide_to_SleepyHead#Important_preferences_settings 7. Important preferences settings] for finding the "Zero Reset" option.<br />
= Basic data interpretation: Overview Data =
Long term trends in the efficacy data are important for many reasons. One of the most important is that we all have the occasional bad night where the AHI is much higher than normal or the leaks are awful. Occasional bad nights do not indicate that there's something wrong with the way the PAP CPAP therapy is going. (Although a really awful night for leaks might indicate it's time to replace those nasal pillows or to check whether the mask was put together correctly). Since sleep doctors meet with many patients each month, they tend to focus almost exclusively on the long term data---a small number of well-understood summary numbers and graphs are easier to review than massive amounts of daily data.
'''Overview data'''
* mostly purple indicate the user had more CAs scored than other events.<br />
Looking at the data as a whole, we see that it took this patient about three weeks to really settle into PAP CPAP and have the AHI come down to what's now his normal range. It's also interesting to note the spike in AHI on June 12. This particular patient had a bicycle accident on that day and got scrapped up pretty good, with a broken toe and a significant lacerations on his right ankle and shoulder. He was in pain that night, which is likely related to the higher AHI.
The usage graph is often mentioned, but it can be seen from the number at the top left of the graph that the patient is averaging 6:57 hours of mask time and that he's only had two days with really significant problems keeping the mask on. (One of those nights was during an overnight driving event where the patient didn't get to bed until 7:00 a.m.; the other was another cross country drive where he got to bed around 3:00 a.m.)
The Session Times graph give a good overview of sleep patterns. If you sleep well, this graph probably won't be of much interest. If you have problems with insomnia or circadian rhythm problems, looking at the patterns in this graph may go a long way towards explaining why you may not be feeling much better even with PAPCPAP: PAP CPAP fixes OSA, but it does not fix bad sleep that are caused by other things. In the patien's patient’s Session Times data, it's easy to see that his wake up times are a bit more regular than his bedtimes. It's also easy to spot which nights he had trouble keeping the mask on.
Scrolling down we can see additional graphs. Three more graphs that are often useful are shown below:
The Leaks and Total Leaks graphs show the maximum, 95%, and median Leaks and Total Leaks for each day. The 95% (or 90%) and median Leak graphs are are more important than the maximum values. The patient has had a few days where his 95% leak rate was pretty high, but not high enough to have had any leaks flagged as Large Leaks in his Daily Data.
The Peak AHI graph gives graphical information about the number of apneas and hypopneas recorded in any 60 minute period during the given night's data. The Maximum Peak AHI is the maximum number of events that occurred during any one hour of the given night; this is a crude measure of how bad the worst hour of the night was. The Maximum Peak AHI values are usually going to be quite a bit higher than the overall AHI for the night because for most of use, once we start PAPing CPAPing we have long period with no events and hopefully many hours where the hourly AHI is at or close to 0.
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''The CPAP Statistics.'' This chart has two distinct '''Report Modes'''. The ''Standard'' mode, which is shown here, is the default mode and it provides summary numbers for standard CPAP data reported for time ranging from the '''Most Recent''' (latest one-night) data to the data for the last year. The ''Monthly'' report gives summary numbers for each of the last 12 calendar months of data.
''Changes to Prescription Settings''. This chart provides a list of all machine/prescription settings you have used. For a newbie, this chart should be relatively straightforward.
''Machine Information chart.'' This shows the make, model, and serial number for each PAP CPAP machine that you've used with SleepyHead, as well as the first and last dates of usage.
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You will notice that the total number of days of CPAP data is listed immediately under the header '''CPAP Statistics'''. CPAP data includes data from any kind of PAP CPAP machine that you have imported into the SleepyHead profile you are using. The dates of the range of data is also listed.
It's important to note that:
'''
Therapy Efficacy data'''
The Therapy Efficacy data are the numbers that measure the overall effectiveness of your PAP CPAP therapy. The whole point of PAPing CPAPing is to get and keep the AHI below 5.0 long term while also having the leaks under control and getting enough sleep to feel well in the daytime. Here are one patient's Therapy Efficacy data:<br />
[[File:Therapy_Efficiacy_zpse827284e.png]]
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* Her '''Last Week''' numbers are quite a bit better than her 6-month and 1-year numbers. That means that her OSA has been better controlled this week than it has on average for the last 6 months. Her AHI numbers tend to be somewhat cyclic each month, and this week seems to have been a "good" week.
* The '''Last Month''' data is a bit better than the 6-month and 1-year data. So the last month has been a pretty good one in terms of PAP CPAP therapy. SleepyHead data cannot provide an explanation of why it's better. However this patient is through her spring allergy season and the summer allergies have not been that bad this year. That may be a partial explanation for why the 30-day numbers are a bit better than the 6-month and 1-year numbers. More than likely her 30-day AHI will go back up once Ragweed starts to pollinate in the fall.
* The '''Last 6 month''' numbers are a tiny bit better than the Last year. The difference is not statistically significant. And taken together, the 6-month and 1-year numbers say that the machine is doing its job of preventing most of her apneas and hypopneas from happening. A long term AHI < 2.0 is quite good.
The ''average'' and ''90%'' leak rates must be interpreted in terms of the statistical meanings of the words average and 90% (90th percentile) of a data set. For those who do not remember any about averages or percentiles, you may wish to read [http://adventures-in-hosehead-land.blogspot.com/2012/03/average-median-95-numbers-guide-to.html Average, Median, 95% numbers: A guide to those who don't remember their introductory stats].
We'll start with the 90% (or 95%) leak rates because they are actually easier to understand in terms of PAP CPAP therapy.
The 90% and 95% leak rates are the 90th and 95th percentiles for the entire set of leak data for the given time frame. We can informally think about the computation needed to find the '''Last Week''' 90% leak rate as follows: Loosely speaking, the PAP CPAP machine has sampled the leak rate a finite number of times in the last 7 days. So for the 7-day 90% leak rate, we can informally think of lining up all the sample leak data points for the last 7 days in increasing order. If there are 10000 sample data points on our list, we find the 90% by finding the 9000th number on the list because .90*10000 = 9000. The 95% leak rate would be the 9500th number on our list.
The 90% leak rates for 30-day, 6-month, and 1-year are found the same way: We line up all the data points for leak rate for the entire time period in increasing order. If there are n points on the entire list, we first find the integer '''k''' that is equal to or just barely bigger than 0.9*n and then we find the '''k'''th number on the list.
The average leak rate for a given time frame is just the (weighted) average for all the leak data in that time frame. In other words to compute the 7 day average leak rate, we look at all the leak rate data for the last 7 days as one data set and find the (weighted) average for the large data set. Loosely speaking, the PAP CPAP machine has sampled the leak rate some very large, but finite number of times in the last 7 days. You add up all the "leak rate data points for the last 7 days" and divide by the total number of data points in the 7 days and you get the weighted average leak rate for the last 7 days.
The average leak rate for the last 30 days, last 6 months, and last year is computed the same way: Informally, you add up all the sample leak rate data points for the last 30 days, 6 months, or year (respectively) and divide by the total number of data points for the same period of time.
'''Pressure Statistics'''
The '''Pressure Statistics''' are not very interesting if you are using a fixed pressure PAP CPAP machine; your max pressure and 90% or 95% pressure levels should equal your pressure setting. Your minimum pressure level and your average pressure level will be less than your pressure setting if you use the Ramp feature. The minimum pressure level will most likely be the starting Ramp pressure.
The '''Pressure Statistics''' are more interesting if you are using an Auto PAP CPAP in Auto mode.
A sample patient's summary Pressure Statistics data looks like this:<br />
* ''The CPAP information'' on the left side of the panel is largely irrelevant at this point. SleepyHead defaults to a statistical model for approximating the (excess) leak for all machines other than the ResMed S9, which records only the excess leak. If you forget to change the Leak Calcs from "Mask Profile" to "Statistical Model" it really doesn't matter.
* ''CPAP clock drift'' should be left at 0 seconds unless you know your CPAP clock is off and you can't change PAPthe CPAP's internal clock. This patient's clock is off by a whopping 23 minutes, and because it's a PR System One-- she can't change the PAPCPAP's clock; hence the offset of 1380 seconds.
* ''Show Leak Redline.'' The default is to have this checked and the default value for the Redline is the ResMed value of 24 L/min. This is a NEW feature in SleepyHead 0.9.6. If you are using a ResMed S9, it's strongly recommended that you make sure Show Leak Redline is checked. If you are using a different machine, this may be a useful option for you, but you will need to change the value for the Redline. More on that later.
* ''Show compliance'' affects how low usage days show up in the Overview data and the compliance data in the Statistics page. The default line is 4 hours for obvious reasons. It's suggested that you leave this alone.
* Does the PAP CPAP report Total Leak Rate or Excessive Leak Rate?
* What is the definition of Large Leak for the particular machine?
* If we're looking at Total Leak, what is the expected leak for the mask at the given pressure(s)?
'''Definition of Large Leak'''
Modern PAP CPAP machines are designed to gracefully cope with a certain amount of excessive leak by blowing additional air into the semi-closed system in order to preserve the desired pressure setting. But even the best of machines cannot accommodate really large amounts of excess leak.
When the excess leaking reaches the point where the machine's manufacturers are concerned that the machine will not be able to properly maintain the therapeutic pressure setting, the leak is defined to be a Large Leak. Different manufacturers define and flag Large Leaks in different ways. Typically, however, Large Leaks are defined in terms of the Total Leak Rate for machines that report Total Leak Rate. ResMed, of course, must define Large Leak in terms of the (excessive) Leak Rate that is reported by their machines.
If you want to add a Redline to your Leak/Total Leak graphs in SleepyHead, our advice is to look at your own Large Leak flags and figure out where they seem to start. If you don't seem to have very many Official Large Leak, then use the above guidelines as a decent enough starting guess for where your particular Redline should be drawn.<br />
In order to adversely affect the efficacy of your PAP CPAP therapy and the accuracy of the data recorded by your machine, leaks have to be both large enough and long enough. As we've just seen, "Large enough" is easily quantified by the manufacturers. But what is "long enough"?
ResMed is apparently the only major manufacturer that has a user-friendly tool for determining whether the official Large Leaks last long enough to compromise the PAP CPAP therapy: The dreaded Mr. Red Frowny Face shows up on the short version of the Sleep Quality Report when Official (ResMed) Large Leaks make up at least 30% of the night.
Since the other manufacturers are "vague" when it comes to describing how long Large Leaks must last to adversely affect the PAP CPAP therapy, we'll take that ResMed definition as a "working" definition:
: '''''If you are in Official Large Leak territory for your machine for at least 30% of the night, then you KNOW you have a Large Leak problem that must be dealt with.'''''
We'd all like a perfect leak line every night. But for most of us, that's not going to happen. Moreover, the battle to eliminate all excess leaks may cause more problems than it fixes. So when are leak lines "good enough" to not worry about it?
In general a Total Leak line will be mostly "fuzzy" flat and stay mostly around the intentional leak rate for your mask and pressure, but tends to have some visible periods of noticeably higher leaks, most of which stay well below the cut off for "Large Leaks" for the given machine. A few very short lived Large Leaks on an otherwise decent night are usually not something that you need to worry about. A Decent Enough Total Leak line has more obvious leaks than a Good one does, but line stays below the Large Leak line for at least 70-90% of the night. (There's some debate between PAP CPAP users of just how long the Large Leaks need to last before they become problematic.)
For ResMed users or for folks who simply want to concentrate on the (excessive) Leak data, a Good Leak line will be "fuzzy" flat, stay mostly around 0.0 L/min, but tends to have some visible periods of noticeably higher leaks, most of which stay below 10-15 L/min. A Decent Enough Leak line has more obvious leaks than a "Good" one does, but line stays below 25-30'''*''' L/min for at least 80-90% of the night. (There's some debate between PAP CPAP users of just how long the Large Leaks need to last before they become problematic).
* ''In general patients can trust the Total Leak data and the machine manufacturer's Large Leak definition more than eye-balling the (excessive) Leak graph in SleepyHead if one is indicating there's a Large Leak and the other is not. That means that users of IntelliPAP machines may have a bit higher "Leak" number than 24-30 L/min before it really counts as a Large Leak; on the other hand users of Icons with masks that have relatively high expected leaks may have Large Leaks where the (excessive) Leak graph is quite a bit lower than 24 L/min: If the expected leak rate of your graph is 45 L/min and you use an Icon, any excess Leak that is more than 15 L/min is likely be flagged as an Large Leak in the F&P software since the Total Leak will be AT or ABOVE 60 L/min, which is the Large Leak line for the Icon.''
'''Problematic, Bad, and Horrible Leak Lines'''
As with many other things concerning PAP CPAP therapy, trending data in the Leak/Total Leak line is also important. If you're trying out a new mask and you're still working out how to fit the mask, you may have one or more nights of really bad Large Leaks. If your mask cushion is starting to wear out, the first sign might be a higher than normal leak line. If you wind up with a bad cold or the flu and you're seriously congested, you might be prone to doing more mouth breathing than normal and your leaks may be (much) higher than typical. So it's important to not over-react to one (or a few) bad nights with respect to leaks, particularly if there's an obvious explanation.
But some new CPAP users (and not so new CPAP users) have real problems getting excessive leaking under control. We now turn our attention to using the Leak/Total Leak line to identify when Large Leaks are '''long enough''' as well as large enough to compromise the efficacy of the PAP CPAP therapy and the accuracy of the data.
There is some differences of opinion among long term CPAP users about how much time you have to spend in Large Leak territory before it becomes clear that you absolutely must do something about the leaks. Some people would say 10% of the night in Large Leak territory is too much; others would say 10% is ok, but 20% is not. Some of this comfort: If the Large Leaks are waking you up, they've got to be dealt with. If you're not feeling better in the daytime, the Large Leaks might be part (or all) of the problem. But if you're sleeping through the Large Leaks and you're feeling good in the daytime, it may not be all that important if you are in Large Leak territory 10-20% of the time on some nights.
'''Mouth Breathing and Other Causes of Leaks'''
A lot of things can cause leaks of all sizes: Fiddling with the mask, jostling the mask to scratch your nose, jostling the mask while turning over in bed, mouth breathing, and facial relaxation (facial sagging) in deep sleep are all capable of causing both small and large leaks. Worn out mask cushions, incorrectly sized masks, overtightened mask straps, and masks that are incorrectly reassembled can also cause leaks. Another potential cause of leaks are pressure increases when using a PAP CPAP in auto mode. Fitting a mask at low pressure tends to be easier than fitting a mask at higher pressures. And if you fit your mask at relatively low pressure, as the pressure increases, the pressure increase itself may cause the mask to lose its seal, and the result is an excessive leak.
Mouth leaks can be particularly problematic for nasal mask and nasal pillows users. Indeed new CPAP users using nasal masks and nasal pillows are often told by other CPAP users that they need to use a full face mask if there is any chance that they might be a mouth breather. And when a newbie posts pictures of problematic leak lines, the first thing that's often suggested is that the leaks are probably due to mouth breathing.
The pattern easy enough to identify. Do we know with absolute certainty that this kind of a pattern is most likely a mouth breathing leak? Of course not but we can often make an educated guess. Plateau type leaks combined with using a nasal mask interface and waking up with a dry mouth usually points to mouth leaks. Whether the mouth leaks are serious enough to warrant doing something about depends on their severity, both in terms of how large the leaks are and in how much they seem to disturb your sleep.
It's also important to point out ''again'' that two of the three probable periods of mouth breathing in that last example stay below the ResMed Redline: In terms of the efficacy of the PAP CPAP therapy, the two smaller mouth breathing leaks are not serious enough to worry about. This runs counter to the commonly accepted notion that you loose all your therapy pressure any time you open your mouth while using a nasal mask: The amount of air you lose through an open mouth depends on a lot of factors, most notably the placement of the tongue. If the front 1/3 to 1/2 of your tongue is firmly planted on the roof of your mouth behind your top front incisors, the tongue effectively blocks off the oral cavity from the upper airway. And if you happen to open your mouth with your tongue in that spot, any mouth leaking may be very minimal as long as you are continuing to breath through your nose. If you start breathing through your mouth, however, the tongue will slip from that position, and as the tongue moves down away from the roof of the mouth, more air will be able to leak out of the open mouth.
Many people do switch to full face masks because of ''suspected'' or ''known'' mouth breathing issues. In a full face mask, you can open and breathe through your mouth without losing pressure. (Mouth breathing inside a FFM may still lead to serious dry mouth issues, however). But many people using FFM still have leak lines that have long plateau patterns reminiscent of mouth breathing. And it is not uncommon for these long plateau leaks to be large enough to be scored as Official Large Leaks. Since mouth breathing is not the (direct) cause of such a leak when you are using a FFM, what is? The most likely cause is the relaxation of the facial and jaw muscles after the mouth has opened. As we sleep, these muscles relax and the facial tissue around the mouth and chin starts to sag. If the lower face sags or relaxes enough, the mask may pull away from the chin and create a potentially large leak. It's also important to remember than FFM have a much larger footprint on the face, and hence there is more surface contact between the mask and the face, and that also can make it harder to seal a FFM in the first place.
It's the same idea with our CPAP machines: As long as the excess leak rate is not too high, the CPAP machine has no real trouble blowing enough new air into the system to compensate for the ''total'' leak rate. In other words, the CPAP can compensate for additional, moderate unexpected excess leaks by simply blowing more air into the system in order to maintain the same amount of pressurization. But there are limits to how much air can be lost before the machine simply can't keep up with its job: Once the total leak rate crosses into official Large Leak territory, the CPAP will have trouble adding enough air to the system to balance out the air leaking out of the system. And hence the machine will have trouble maintaining the desired pressure level.
And that's the fundamental problem with Large Leaks: If they last for a long enough time, the machine may become unable to maintain a therapeutic pressure inside the upper airway. And if the CPAP cannot maintain the necessary therapeutic pressure level, the upper airway becomes more vulnerable to collapsing. Which means that the PAP CPAP machine is less effective in preventing apneas and hypopneas from occurring, and so the CPAP therapy itself is compromised.
But there is another problem a full efficacy PAP CPAP machine faces when the leak rate approaches or stays in official Large Leak territory for any length of time: The breathing itself becomes more difficult to track. PAP CPAP machines track our breathing by measuring subtle changes in the back pressure, but when the leaks start to approach the boundary of Large Leak territory, the "signal noise" caused by the leaks makes it harder for the machine to distinguish the subtle changes in back pressure that are used to detect the breathing. This can cause the Flow Rate data to become distorted and garbled; often times the perceived amplitudes of the inhalations and exhalations are significantly reduced even though normal breathing may be occurring. The following figure is from the discussion in the [http://www.devilbisshealthcare.com/files/IntelliPAP%20AutoAdjust%20Clinical%20Overview_LT-2089.pdf Clinical Overview for the DeVilbiss IntelliPAP AutoAdjust] concerning what happens in the presence of excessively large leaks:
<br />
[[File:leak_effect_on_wave_flow_zps42c5342e.jpg]]
Most sleep doctors and most OSA patients never really concern themselves with detailed efficacy data beyond the nightly and long term AHI data. And that's ok: If the nightly AHIs are almost always below 5.0 and you're feeling well, there's really no need to look at the detailed data available in SleepyHead about each and every event the machine recorded over night. But if you're a data hound, the stuff you can see in the Flow Rate data can be fascinating. And if you're not feeling as well as you hoped with CPAP therapy, sometimes examining the Flow Rate data in more detail can shed some insight into what might be going on.
The information on this page is written for the curious CPAP users who simply wants to know more about what the Flow Rate data shows and what it may indicate about the quality of therapy. None of this information should be considered medical advice. If you are experiencing problems with your PAP CPAP therapy, you should consult your sleep doctor.
But our CPAPs have no way to determine the effort to breathe. Hence CPAPs cannot distinguish between obstructive and central apneas in the same way that the technician monitoring a PSG does. Originally full efficacy data CPAPs did not try to distinguish between obstructive and central apneas. (The F&P Icon still does not try to distinguish types of apneas.) But when manufacturers started designing Auto CPAPs, a potential problem had to be addressed in the Auto algorithms: A minority of CPAP users are sensitive enough to pressure to develop problems with pressure-induced central apneas. And the tendency to have problems with pressure-induced centrals is more pronounced the higher the pressure setting on the CPAP. Hence early APAP Auto algorithms often were designed to NOT increase the pressure in response to apneas scored at pressures of 10cm or greater. In an effort to get around this difficulty, many of the current generation of full efficacy CPAPs make an effort to distinguish between apneas are presumed to be obstructive and those that are presumed to have a high probability of being central, and an APAP with such a "central apnea detection" algorithm can be programmed to respond to the apneas classified as obstructive and ignore the other apneas.
ResMed and PR PAP CPAP machines use (different) proprietary algorithms to test the patency of the airway and use the result to classify each apnea as a ''clear airway apnea (CA)'' or an ''obstructive apnea (OA)''. When the data from the algorithm leads to an ambiguous result, the apnea may be scored as an unknown apnea (A or UA). Both ResMed and PR Auto machines will increase the pressure in response to clusters of OAs, but they will not increase the pressure in response to apneas scored as CAs.
DeVilbiss machines use a very different algorithm to classify each apnea as an ''apnea (A)'' or a ''non-responding apnea (M or NRA)''. A DeVilbiss Auto machine will increase the pressure in response to events classified as "apneas", but it will not increase the pressure in response to "non-responding" apneas.
As near as I can tell, F&P machines do not try to distinguish the type of apnea. And I have not been able to find any specific information about how the F&P Icon responds to machine scored apneas.
It's also important to remember that the ResMed and PR algorithm for distinguishing between OAs and CAs and DeVilbiss algorithm for distinguishing between As and NRAs are not infallible. They are prone to misclassifying apneas under certain circumstances. For most users, it's not a huge problem, but for a small number of users, it can be an issue. We're not familiar enough with the DeVilbiss alogrithm to have a good sense of its limitations. But both the ResMed and PR algorithms are based on using variations in the PAP CPAP pressure to test the patency of the upper airway. As such they both have the same broad characteristics:<br />
'''Other flagged events'''
In addition to scoring apneas and hypopneas, many PAP CPAP machines score ''snoring and/or flow limitations (FL)''. The way machines score this things varies quite a bit, and they are discussed at length in [http://www.apneaboard.com/wiki/index.php?title=Beginner%27s_Guide_to_SleepyHead#Snoring_Data 10. Snoring Data] and [http://www.apneaboard.com/wiki/index.php?title=Beginner%27s_Guide_to_SleepyHead#Flow_Limitations 11. Flow Limitations].
In addition to scoring OAs, CAs, Hs, snoring, and FLs, the '''PR System One machines''' also score ''respiratory effort related arousals (RERAs)'' and '''periodic breathing''' (PB) in the events table with flags on the Flow Rate curve.
A bit of PB now and then is nothing to worry about. However, there is one form of PB that is called Cheyne-Stokes Respiration (CSR) that is clearly associated with some forms of heart disease, including congestive heart failure. CSR is very regular and has a CA at the nadir of the cycle (although the CA may be mis-scored as an OA). If you have serious heart disease and you see a lot of PB scored in your flow rate data, it is worth mentioning it to your cardiologist as well as your sleep doctor.
''Detecting Periodic Breathing on other PAPsCPAPs''
Once you know what PB looks like, you can often spot suspicious patterns by simply scrolling through the Flow Rate data in with a 5-10 minute window. Any periodic waxing/waning patterns will be show up at that magnitude. Whether this is worth doing on a regular basis is another question altogether. Unless you have a co-morbid condition that is associated with PB (such as congestive heart failure), PB is not something you need to spend much time worrying about or trying to locate in your data.
ResMed S9s, PR System One CPAP and DeVilbiss IntelliPAP machines record snoring data. F&P Icons do not record snoring data.
'''How does a PAP CPAP machine detect snoring?'''
CPAP machines do not have microphones attached to them. So your CPAP is not listening to the sound of your snoring. So how does it actually detect snoring? It analyzes the Flow Rate data.
'''Equipment description'''
Make sure your equipment profile is up to date and correct. Be precise in describing your PAP CPAP equipment. There are six commonly used ResMed S9s and at least that many commonly used PR System Ones; we need to exactly which model you are using. If you are including leak data, it helps to remind folks if you are using a FFM or not: It's irksome to be repeatedly told that you really need to switch to a FFM because of mouth breathing if you already use a FFM because you already know you're a mouth breather.
'''Getting feedback on the question: How am I doing?'''
* Let the S9 erase the card and rewrite the summary and compliance data to the card. You will NOT lose any data that you've already imported into SleepyHead. And the summary and compliance data that your DME and sleep doc care about will be written back to the card.
* To prevent the problem in the future: Be sure to lock the SD card before inserting the SD card into your computer or card reader. You lock the SD card by sliding the "Lock" tab on the side of the card to the Locked position. That will prevent the operating system from writing hidden files to the SD card.
* After importing data into SH and removing the SD card from your computer, remember to unlock the card before putting it back into your S9 PAPCPAP. If you forget to unlock the card, you might see an error message on the S9's LCD telling you that the inserted card is read only.
'''NOTE:''' Using ResScan on a Win 8.1 or Win 10 machine will NOT prevent this problem from happening; Windows will still write hidden files to an unlocked SD card and when you put the card back in the S9, the S9 will still insist on erasing the contents of the card.
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