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What do the numbers mean?

This area is for CPAP Mask and CPAP Machine Related Questions used in the treatment of Sleep Apnea.

What do the numbers mean?

Postby Stevah » Sat Aug 28, 2010 3:13 pm

As a new poster I want to express my personal gratitude and appreciation for all the time and experience that many have put into their posts on this forum that have helped me so much already.

Currently I am doing nightly battle with my second hybrid mask. I actually stopped treatment for over two months because it seemed like I was losing more sleep than I was gaining. With new resolve I have 4-5 different masks on order and I will get this problem fixed.

Having been inspired by some of the forum responders to look closely at my numbers from my Bipap-auto I have started writing down what the machine tells me as far as certain statistics about my sleep (on average for 7 days).

If there is a good post (or copy/paste) on what this info means and what are the good numbers to aim for; I would be grateful and feel free to be as technical as needed.

I will give my current numbers (7 day only) if anyone has a comment I am open (and not sensitive).

Specifically: I am looking for info on:
APN-HYP Index.........(3.3) (down from 5.0 two days ago)--is this per day or per hour?
System leak.............72.4 same question
90% pressure...........12.0/10.0...I have no clue about what these numbers mean. Is this Ipap/Epap?

I understand Sessions > 4 means: the number of times that I have had a sleep session with the machine over 4 hours.
in 7 days is a 2; in 30 days is a 7.

I know that my numbers will improve when I resolve the mask issues but what are good numbers? Can they be perfect?

Posts: 20
Joined: Sun Aug 22, 2010 11:11 am
Location: Phoenix, AZ

Postby sleland » Sat Aug 28, 2010 7:04 pm

There are others on this forum much more knowledgable than I, but I do know that the goal is an AHI of less than 5 - looks like you are succeeding with that. That number is the average number of apneas and hypoapneas per hour. I think others will need to know what machine and mask you are using to help you with the leak number - some machine reports leaks as liters per second, others as liters per minute. The acceptable leak rate depends on the mask you are using. You might want to fill out your "signature" on your profile with machine, mask, and settings numbers - that will help with answers.
Severe sleep apnea diagnosed 4/2010
Resmed S8 Autoset II w humidifier
Swift LT for Her
Pressure set at 6 - 16
Posts: 253
Joined: Tue May 04, 2010 1:31 pm
Location: Montana

The basics

Postby Stevah » Sun Aug 29, 2010 12:40 am

Ok, leave it to me to ask a question that I should know the answer to. Having asked the questions, I decided I had time to finally do my homework. So here are some definitions.

The following info was gleaned from the web and my User Manual (Respironics).

APN-HYP Index.........
ANSWER: The Apnea-Hypopnea Index (AHI) is an index used to describe the severity of sleep apnea. It is computed from the total number of complete cessations (apneas) and partial obstructions (hypopnea) of breathing PER HOUR of sleep. Pauses in breathing must last for at least 10 seconds; these pauses are associated with a decrease in oxygen in the blood. The AHI is used to classify the severity of sleep apnea (regardless of its cause) as mild 5-15, moderate 15-30, and severe is greater than 30 per hour.

System leak.............
ANSWER: In Liters of air PER MINUTE. The system leaks are a total of the INtentional (necessary exchange of exhaled CO2 and air from the mask) and UNintentional or undesirable mask leaks. Leaks can of course also rarely occur at other places in the pathway of air as it travels through the humidifier and hose.

Obviously we want to eliminate the undesirable system leaks; I still have no idea what would be a good number for this statistic. Evidently it is mask dependent. The normal volume someone might breath while awake is 8-9 Liters/minute while sitting up. How that number might play into a CPAP system's function is unknown to me. Hopefully someone with some technical knowledge will weigh in on this.

90% pressure..........
ANSWER: [This number is found on auto titrating machines only; when that function is enabled]
This is your auto function machine titrated IPAP/ EPAP numbers. The 90% pressures are the pressures that your machine delivers 90% of the time. IPAP is inspiration or inhaling, EPAP is expiration or exhaling. These numbers are limited by the settings from your sleep study set by your DME provider.

Sessions > 4............
ANSWER: This is the number of therapeutic sleep sessions. A therapeutic sleep session is considered to be at least 4 hours long by this manufacturer (Respironics).

So these are the answers that I found to the questions I asked above this morning. They are by no means authoritative or conclusive. We will have to wait for an expert or 2, especially on the System Leak question.
Last edited by Stevah on Sun Aug 29, 2010 11:07 am, edited 1 time in total.
Mild obstructive apnea
Respironics Bipap auto M series w/humidifier
Current mask: nasal pillows
Pressure: currently 10.5 Ipap 9.5 Epap.
Card reader and V2.0 software.
Thankful for: better sleep quality
Posts: 20
Joined: Sun Aug 22, 2010 11:11 am
Location: Phoenix, AZ

Postby CrohnieToo » Sun Aug 29, 2010 8:39 am

Do you still have the literature that came w/your current mask? There is a table in that literature that gives the allowed or intended leak rate at your set pressure. Leak rates run along the left side vertically and pressure settings run along the bottom. The graph line indicates what the allowed vent rate is at any particular pressure setting. You deduct that allowed vent rate from the reported Leak rate to get your actual leak rate.

I "think" that an actualy Leak rate of 40 is the maximum that these PAPs can compensate for. And an actual Leak rate under 26 is acceptable. I "think" this holds true for both Resmed and Respironics PAPs.

You will get more accurate data from the EncoreViewer patient software which can be purchased online and would also need the Mako Infineer DT 3500 cable reader. Insurance does not pay for software and cable reader, it would be an out-of-pocket expense. Or - you could take your data card in to your local DME provider and ask them to do a data download for you. They may or may not charge you for the download.
ResScan 3.10 - Resmed S8 ResLink & oximeter
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PR SystemOne BPAP Auto w/Bi-Flex & Humidifier - EncorePro
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Machine: Resmed S8 VPAP Auto
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Year Diagnosed: 2006

More numbers?

Postby Stevah » Sun Aug 29, 2010 9:05 pm


I did look in both of my mask books, they have about 40L/min. of leakage at 12 L/min. of pressure as normal and expected. So...anything over that would be a LEAK. This is not news to me because not one night goes by that I don't wake up to find one nasal pillow aimed into outer space. The new masks are coming.

I did take your advise and found a good deal on the card reader and Encore V2.0 software on a CPAP site. I looked around quite a bit at version 1.0 vs V 2.0; and the card reader (one choice only that works it seems). Prices ranged from $109.00 (free shipping)-$178.00. (Be very careful as many adds say, "with card reader" in the headline; but if you read the notes carefully they will not describe both. This is because they are not selling both--even thou they implied that they were. Be very carefull.
Evidently more information is key for some to get the best night sleep possible.
I like numbers and I definitely need a better quality of sleep. Thanks. :-D
Mild obstructive apnea
Respironics Bipap auto M series w/humidifier
Current mask: nasal pillows
Pressure: currently 10.5 Ipap 9.5 Epap.
Card reader and V2.0 software.
Thankful for: better sleep quality
Posts: 20
Joined: Sun Aug 22, 2010 11:11 am
Location: Phoenix, AZ

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