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[MoonBear]

Hi,

I have been doing apnea therapy for three nights now, and constantly bless this forum for my equipment choices. Because of all of you, I got past denial, fear and into treatment, understanding that the onus for making good choices would be on me.

Today, I started reading research here to start understanding how to take control of my treatment. My original goal to start has been accomplished. My memory is not very good (gee, I wonder why), but I keep running into the term AHI, and other stats that I do not understand. So it's time for phase 2. I am trusting my S9 is doing its job during these first two weeks of treatment until my pulminologist reads the data card, but I know from reading posts hear that I must understand the machine's information to truly manage my therapy.

I would love any recommendation for any articles hear on the basics of understanding the measurements used in assessing the quality of treatment and am very willing visit the library for good books to read. There are so many, I am not sure which are worth the time.

Also, can anyone tell me if I should have gotten a practitioner manual with my S9? I didn't. And have I understood posts here correctly when I think that there is no Mac software I can use with the S9 Elite?
Thanks very much for the help. I appreciate it.

Namaste, MoonBear

[Julie]

Hi, unfortunately no Mac software (though it keeps being promised). You can get the clinical manual at Apneaboard.com, plus loads of great information by clicking on the lightbulb at the top of this forum's main page.

[robysue]

Hi,

I have been doing apnea therapy for three nights now, and constantly bless this forum for my equipment choices. Because of all of you, I got past denial, fear and into treatment, understanding that the onus for making good choices would be on me.

Today, I started reading research here to start understanding how to take control of my treatment. My original goal to start has been accomplished. My memory is not very good (gee, I wonder why), but I keep running into the term AHI, and other stats that I do not understand. So it's time for phase 2. I am trusting my S9 is doing its job during these first two weeks of treatment until my pulminologist reads the data card, but I know from reading posts hear that I must understand the machine's information to truly manage my therapy.

You are right, you need to understand what all those numbers mean both to understand whether your therapy is working well and how to really manage it. I'll start with some really important key definitions so you know what these numbers actually mean. It's easiest to start with some examples. Since you don't say whether you're using an S9 Elite (CPAP only) or an S9 AutoSet running in Auto mode, I'll assume you've got the S9 AutoSet running in Auto. And since you didn't include any numbers in your post, I'll start by making some numbers up.

First, lets suppose that you slept with the S9 running for 7.5 hours and we're looking at the overnight data in ResScan or off the LCD for the numbers it shows. Now lets suppose that ResScan says that your Leak Rate data looks like this:

Median = 1.0 L/min
95% = 2.5 L/min [This is the Leak number shown on the S9's LCD]
Max = 15 L/min

And lets suppose your pressure data looks like this:

Median = 7.5
95% = 9.8 [This is the Pressure number shown on the S9's LCD]
Max = 10.2

And finally lets suppose that your indices numbers on the LCD look like this:

AHI = 0.9 (Shown on the S9's LCD)
AI = 0.6 (Shown on the S9's LCD)
CAI = 0.1. (Shown on the S9's LCD)
And even though the OAI and HI are not shown on the S9's LCD, they're easy to get: the OAI = 0.5 = 0.6-0.1 and the HI =0.3= 0.9-0.6.

First the AHI, AI, CAI, OAI, and HI are all indices. They indicate how many events of the given type you had per hour on average during the time the machine was on. The machine computes each of these numbers by dividing the number of events (of the particular type) by the time the machine was running. We can compute the number of events of each type without going into Rescan as follows:

(0.9 events per hour)x(7.5 hours) = 6.75, which equals 7 events that night (because Resmed truncates the decimal, always round UP)
(0.6 apneas per hour)x(7.5 hours) = 4.5, which equals 5 apneas that night
(0.1 central apneas per hour)x(7.5 hours) = 0.75, which equals 1 central apnea that night

A bit more arithmetic shows that there were likely 2 hypopneas (7 events - 5 apneas = 2 hypopneas) and 4 obstructive apneas (5 apneas - 1 central apnea = 4 obstructive apneas)

Now let's look at what the rest of those numbers actually mean.

The median leak rate = 1.0 L/min means that for 50% of the time the S9 was on, your leak rate was LESS THAN or EQUAL TO 1.0 L/min. And so for 50% of the night, your leak rate was also GREATER THAN or EQUAL TO 1.0 L/min. So in the 7.5 hours you slept with the machine, for 3.25 hours (3 hours and 15 minutes) you had a leak rate of LESS THAN or EQUAL TO 1.0 L/min.

The 95% leak rate = 2.5 L/min means that for 95% of the time the S9 was on, your leak rate was LESS THAN or EQUAL TO 2.5 L/min. And so for 5% of the night, your leak rate was GREATER THAN or EQUAL TO 2.5 L/min. Now it's important to realize that 5% of one hour is equal to three minutes. Since you slept for 7.5 hours, that means your leak rate was GREATER THAN or EQUAL TO 2.5 L/min for a grand total of (3 minutes)*(7.5 hours)=22.5 minutes. That 22.5 minutes of "high leak rates" might be in one giant half hour leak or it could be in several smaller leaks---the only way to know is that to look at the detailed graphs in ResScan. [You find the detailed graphs under the "Detailed Graphs" tab. If you only download "summary data" the detailed graphs won't be there.]

The max leak rate=15L/min indicates that at some point when the S9 was sampling leak data, it detected a leak that was as large as 15L/min. It may have been a very short lived thing---when you broke the seal to scratch your nose for example. Or it could be that on one or two of the big leaks that you had, the leak pretty quickly went from in the neighborhood of 2.5 L/min to 15 L/min and stayed there. But you know for sure that you could not have leaked at a rate of 15L/min for more than about 22 minutes because of the 95% leak rate number and the time the machine was on.

Interpreting the leak rate data is also important:

First, on the Short Sleep Quality menu, if you see a Red Frowny face, that indicates your 75% leak rate is AT or ABOVE 24 L/min and Resmed's litertature indicates that you are leaking AT or ABOVE a rate of 24 L/min for 25% of the night. And at that point, the ResMed engineers believe that your therapy can and probably is being compromised.

Many people take the 95% Leak Rate to be the key stat Leak data. But it is worth looking at the median leak rate as well, in my opinion. The reason I look at both is that the median leak rate tells me whether I was leaking off and one all night long or not, where the 95% leak rate tells me if my worst leaks were bad ones or not. To illustrate what I mean, let's look at two examples:

Person A sleeps for 7.5 hours and is leaking off and on all night at a rate of 5.5 L/M and for about 25 minutes during the night, the leak rate actually is between 7 and 10 L/min. So A's leak numbers look like this:

median=5.5, 95%=7.0, and max=10.0

Now suppose Person B sleeps for 7.5 hours and has NO leaks at all for most of the night, but has ONE 25 minute leak where the leak rates are from 8 to 10 L/min during this leak. B's leak numbers look like this:

median=0.0, 95%=8.0, and max=10.0

Neither person's leak rates are grate enough to trigger the Red Frowny face in the short Sleep Quality menu on the LCD. But Person A is likely to be having more significant problems with comfort due to leaking all night long.

Obviously, the closer to 0 your leak rate data is, the better obviously. But the information from Resmed seems to indicate that leaks above 24 L/min (the RED LINE in ResScan's detailed graphs) are enough to cause problems with the algorithms the S9 uses in order to detect and respond to apneas, hypopneas, flow limitations, and snores. So in any case you really want your 95% leak rate under 24 L/min to insure that you're getting some kind of meaningful therapy. But comfort is as a much of an issue as therapy is in my opinion: Nasty leaks cause most people real discomfort and they frequently cause people to wake up multiple times during the night to fiddle with the mask even when the leak is well below 24 L/min. For me, I don't worry at all if my 95% leak rate is below 10 L/min unless I had to fiddle with my mask more than once in the night. And if I wake up multiple times needing to fiddle with my mask because of leaks, then the leak rate IS a problem regardless of how low the 95% leak rate is.


If you are using the S9 in Auto mode the pressure numbers are siimilar. [If you are using CPAP mode, the pressure is constant, so all three numbers will be the same when you look at them in ResScan.]

The median pressure = 7.8 means that for 50% of the time the S9 was on, your pressure was LESS THAN or EQUAL TO 7.8cm. And so for 50% of the night, your leak rate was also GREATER THAN or EQUAL TO 7.8cm. So in the 7.5 hours you slept with the machine, for 3.25 hours (3 hours and 15 minutes) you had a pressure of LESS THAN or EQUAL TO 7.8cm.

The 95% pressure = 9.8 means that for 95% percent of the night, the S9 was running at a pressure that was LESS THAN or EQUAL TO 9.8 cm. And so for 5% of the night, the S9 was running at a pressure that was GREATER THAN or EQUAL to 9.8cm. Again, it's useful to realize this means that the pressure was GREATER THAN or EQUAL TO 9.8 for about 22.5 minutes.

The max pressure = 10.2 means that at some point(s) during the night, the S9 reached a pressure of 10.2cm. You know (for sure) from the 95% data that the S9 was running at a pressure of 10.2 for less than about 22 minutes out of the night.
ou can also determine the number of events you had overnight by doing a simple multiply of the LCD's AHI, AI, and CI numbers if you want to---you don't need to go into ResScan to determine how many events the S9 scored unless you want to.

For Pressure, many people focus on the 95% pressure figure as the important one: The usual rationale for looking at the 95% number is that it is theoretically high enough to prevent most of your apneas and hypopneas. And most people seem to tolerate this pressure rather well. But for auto-titrations, they usually want the 95% number over several nights in a row so they can see what pressure the S9 tends to settle at. During my week or so of auto-titration, the individual 95% numbers ranged from something like 7.4 (on the low end) to 8.2 on the high end. The whole week came in at something like 7.8 or so. So my straight titrated pressure is about 8cm. Folks around here seem to have several ideas on how to set the min and max ranges for an APAP range. But there does seem to be a consensus that the max needs to be set ABOVE the 95% and that the min needs to be set not much lower than that 95% number. But your mileage may vary.

Also, can anyone tell me if I should have gotten a practitioner manual with my S9? I didn't. And have I understood posts here correctly when I think that there is no Mac software I can use with the S9 Elite?
Thanks very much for the help. I appreciate it.

Namaste, MoonBear

Contact the user named Uncle_Bob. He can give you links to both the clinical manual and the ResScan software. Yes, it's unfortunate that the software won't run on a mac unless you have some kind of a windows environment installed. One alternative, however, is to get a cheap, older PC running Vista with Service Pack 3 (I think it's Service Pack 3) and install the CPAP stuff on that machine. That wound up being the easiest solution for this Mac user. Of course, we have a bunch of older PC's lying around the house not doing anything and my hubby is a PC and so he set the machine up for me.

[jbenenson]

In case you don't know, if you hold down both the info and setup buttons simultaneously on the S9 you will get a detailed report of "last night" performance. If you hold down both the setup and button to the right for three seconds you get into clinician mode where you can set the machine configuration to whatever you want. Don't be afraid to try different settings to achieve your personal maximum therapy.

[Slinky]

But don't start changing your settings until you are confident you understand what you are doing and WHY. AND when you DO make a change to your settings make only ONE change and stay there for a WEEK BEFORE making any other ONE change.

Keep in mind that as good as these PAPs are at collecting and reporting data, they are NOT as accurate as a full night's in-lab PSG wherein much more information is able to be recorded. The value of the PAP data is for spotting TRENDS.

[KatieW]

As Julie said, the cpap wicki, yellow light bulb will lead you to many articles on cpap, and keep you reading for a long time. Another good sources is:

http://smart-sleep-apnea.blogspot.com/

And for S9 ResMed AutoSet users:

http://www.osahelp.com/

A good book is: http://www.amazon.com/Sleep-Apnea--Phan ... 231&sr=8-2

If there is a specific topic and you want to know if there have been previous forum discussions, then you can also do a search, using the search function of this forum, eg. rain out, aerophagia, etc.

When I 1st started, I learned that there are certain members, who's posts I found particularly informative. You can click on their name, and find and read their previous posts. Rested Gal comes to mind, but there are many others. I bookmark, or save sections of posts that I might need to refer to again.

[MoonBear]

I am so grateful for all the wise counsel. I will study and learn. While it will take time to assimilate and be fluid with the indices and the data, I will get there thanks to such great help.

Namaste,
MoonBear