Understanding Resmed 10 Autosense

[millerdq]

I'm still learning/adjusting to my Resmed 10 Autosense. What an experience! Dr. refers me to equipment provider, equipment provider can't or won't answer questions, equipment manufacturer supports their website, not their equipment, and refers me to physician. Looks like the DIY route for me. Thanks to this forum, I've found the Clinical Menu and software for viewing my data. Now trying to learn and understand both.

Perhaps someone can help me with a couple questions.
1. My Sleep Report shows AHI, Total AI, and Central AI. AHI is adequately explained, but the other two numbers are not. Does anyone know what accounts for the difference between AHI and the other two scores?

2. The pressure guage on my machine quickly ramps up to 4 and remains there as long as I am awake. After waking up, it is higher--in the 10-12 range--from which it never drops even when I lay awake for quite awhile. I'm wondering if the guage represents the instantaneous pressure or the peak pressure?

3. I understand the difference between obstructive apnea and a central apnea. Just wondering what metric(s) the machine uses to distinguish them.

[player]

Get Sleepyhead free software for better reporting.

Get your online manual so you can change your own settings.

What are your numbers?

Ramping up to 4 seems low. I turned off the ramp feature, mine goes to where I set it, 11, and doesn't go below 11 and higher than 16. Your settings should be different of course.

[FrankNichols]

There are two ways the Autoset moves pressure up:

1. During ramp time, it "ramps" up the pressure to the low pressure setting if you are using Auto more or the THE pressure if you are using CPAP mode. The time it takes to ramp up to that pressure is set in the ramp time setting.

2. The pressure is increased when one of several conditions occur - Flow Limitation above some amount (I think around .4), an obstructive event is detected and Hypopnea event occurs. Central events do not result in a raise of pressure.

Once the pressure is raised (it raises it fairly quickly) it takes about 20 minutes to reduce the pressure back down. If you do not have any events, you pressure should remain at the low setting in Auto mode. I expect the 20 minutes is "forever" in your laying the awake time frame.

[PoolQ]

You have ramp turned on, I use it also. The machine starts at 4 (you can change this) and takes 45 minutes (you can change this) to ramp you to your therapy starting pressure (you can change this). It is intended to give you time to fall asleep before it hits you with therapy pressure, some need this and some don't, you can turn it off or on. 4 is typically considered low and may make you feel starved for air.

From what I understand:
AHI = apnea hypopnea Index (how many OA + CA + hypop you are having per hour over the sleeping time
total AI = total apnea index as above without the hypopneas added in
central Ai = central apnea index well centrals only, Airsense cannot treat these and depending on your pressure, and you, may actually cause some of these.

lasting 10 seconds for both, one is blocked airway and the other the airway is open but there is no effort to take a breath (central brain stem). the machine can tell if there is a blockage in place or not

You are asking the right questions

[sptrout]

You have ramp turned on, I use it also. The machine starts at 4 (you can change this) and takes 45 minutes (you can change this) to ramp you to your therapy starting pressure (you can change this). It is intended to give you time to fall asleep before it hits you with therapy pressure, some need this and some don't, you can turn it off or on. 4 is typically considered low and may make you feel starved for air.

From what I understand:
AHI = apnea hypopnea Index (how many OA + CA + hypop you are having per hour over the sleeping time
total AI = total apnea index as above without the hypopneas added in
central Ai = central apnea index well centrals only, Airsense cannot treat these and depending on your pressure, and you, may actually cause some of these.

lasting 10 seconds for both, one is blocked airway and the other the airway is open but there is no effort to take a breath (central brain stem). the machine can tell if there is a blockage in place or not

You are asking the right questions

PoolQ is correct in the explanation of AHI, but I will throw-in a comment.

AHI is the ratio of apnea events (number of those of at least 10 seconds long) to the amount of time in sleep calculated in "hours". The calculated AHI is a little bit of a toss of the dice in two aspects: 1) you have to depend on the machine to accurately count the number of "events" and 2) measuring the correct sleep hours. There is nothing you can do but accept as true the number of events, but the time asleep is always wrong. The machine cannot tell if you are asleep or not so it just uses the total time that it is "on" as the sleep part of the calculation. No one falls asleep the minute they turn the machine on, and few wake-up just in time to jump out of bed and turn it off. Therefore, your calculated AHI will always be on the "better than actual" side, maybe way better if you do not sleep much during the night for reasons unrelated to SA, which will then give you a much better number (the "events" will be down, but the hours of sleep will be normal even though you may have been awake most of the night).

[FrankNichols]

AHI is the ratio of apnea events (number of those of at least 10 seconds long) to the amount of time in sleep calculated in "hours". The calculated AHI is a little bit of a toss of the dice in two aspects: 1) you have to depend on the machine to accurately count the number of "events" and 2) measuring the correct sleep hours. There is nothing you can do but accept as true the number of events, but the time asleep is always wrong. The machine cannot tell if you are asleep or not so it just uses the total time that it is "on" as the sleep part of the calculation. No one falls asleep the minute they turn the machine on, and few wake-up just in time to jump out of bed and turn it off. Therefore, your calculated AHI will always be on the "better than actual" side, maybe way better if you do not sleep much during the night for reasons unrelated to SA, which will then give you a much better number (the "events" will be down, but the hours of sleep will be normal even though you may have been awake most of the night).

This is why I when I review the Sleepyhead charts I look at the full session first and then I drag select from the starting sleep time to the waking time. This creates a selection and SH calculates the AHI for just that time period and displays it just above the flow rate chart.

If you spend some time examining the charts it doesn't take long before you can recognize when you fall asleep and when you wake by the breathing patterns. Or like me, you can buy a ResMed S+ (around $65) which provides a non-contact sleep monitor that reports in the morning when you were awake and when you were asleep and how much time you spent in REM, Deep and Light sleep states.

I find it interesting to see how "intense" the apnea cluster bombs I experience are during REM sleep are - meaning on my charts I see a large increase of Apnea events occasionally during what I am pretty sure is REM sleep, these periods can sometimes have AHIs as high as 30 to 50 for me, but they only last for 15 to 30 minutes.

[green wings]

30 to 50? Wow, and here I've been annoyed because my middle-of-the-night cluster bomb period has an AHI of 10-15.

Note to millerdq here: If you are looking at graphs in SleepyHead, there is a graph for AHI. That AHI number is an hourly moving average, so if your apnea events aren't spread evenly throughout the night, the AHI graph will have a higher maximum value than the AHI number you'll see on your machine or on the pie chart and nightly average stats in SleepyHead.

I find it interesting to see how "intense" the apnea cluster bombs I experience are during REM sleep are - meaning on my charts I see a large increase of Apnea events occasionally during what I am pretty sure is REM sleep, these periods can sometimes have AHIs as high as 30 to 50 for me, but they only last for 15 to 30 minutes.

[PoolQ]

accurate numbers: not that any of us are typical, but if you don't use ramp and don't wake up many times during the night, the average person falls asleep in 22 minutes and 22 minutes out of 8 hours does not throw your average off by much. Now if you are like me and wake up 4 times a night and use ramp at 45 minutes, why then yes it does add up. But I do sleep about the same every night so using an average number to measure my relative sleep quality works just fine. Does it really matter that your AHI is 4-5-6, not at least in my book

[trish6hundred]

Hi millerdq,
WELCOME! to the forum!
Much success to you with your CPAP therapy and hang in there for more responses to your post.

[chill]

I drag select from the starting sleep time to the waking time. This creates a selection and SH calculates the AHI for just that time period and displays it just above the flow rate chart.

Dang. I have spent a long time looking at SH wishing for just this feature! Thank you, Frank.