AHI less than 1?

[jbn3boys]

I know there are some people on the forums who routinely have AHI numbers less than one.

It still seems like an unreachable goal to me.

I've started to wonder if there is a correlation between what I would consider extremely low AHI (less than 1, or even less than 1.5), and the machine used. I think I've read here that different machines use different logarithms, so is it possible that it is more likely with one machine to get great numbers? And likewise, more difficult to get great numbers with other machines?

Anyone have any insight?

Or, if you have great numbers, what machine are you using?

[robysue]

For those of us using ResMed S9's there's been talk that the S9 may undercount hypopneas. From what i've read here, it seems like the S9 certainly scores fewer hypopneas than the S8's do. It may be that the PR S1 algorithms just score more "maybe" events as "real" events. How are you feeling with your current AHIs?

[JohnBFisher]

Older Resmed units would tend to overscore the hypopneas, so would only rarely have an AHI under 1.

Some machines do not have a "settle time", and start scoring right away. As you fall asleep, you tend to have higher than normal respiratory events. These are normal and should NOT be counted against the AHI value. Such machines will tend to have a higher AHI value.

If you awaken during the night, even if you don't get up, you will go through that transition to and from sleep. And you will experience apnea events that should not be included in the AHI value. Of course none of the machines can determine if you woke up during the night.

And so it goes .. Which is why we always get back to:

How do you feel?

If you feel rested, then even if the AHI is 5, the therapy is working. If you feel miserable and the AHI score is 0, then the therapy is not working. Think of AHI as a windsock that give you a general feeling of how you slept. But it's not the be all and end all.

[Hawthorne]

I used an M Series auto before I got my Sytem One auto.

With the M Series, I regularly got under 1 AHI - and got 0 AHI quite a number of times.

With the same settings on the System One, I have only been below 1 AHI twice since I got it in March. I am regularly 2 or less AHI though with the System One.

The M Series, did not count CAs in the AHI as the System One does so I think this is the difference. My CAs are generally at sleep onset, while I am settling in. I don't worry about these since I, like many people, seem to hold their breath unconsciously, while they are settling done.

If I subtract the CAs from my total AHI, I would often be 1 or below with the System One.

[brazospearl]

0 events is certainly reachable for some. The rest of us might be nicely surprised if that happens, but have to settle for a few more than 0. If your numbers run close to 0, it could be that a different machine with a different algorithm might show a 0, but it might show an increase as well. Instead of trying for 0, you might want to pay attention to your personal "magic number." The medical folks use 5 as the magic number, but it varies for many people. My AHI is typically around 1.6 (mostly hypopneas) and I've found that anything over 3 means I feel worse the next day. While 0 would be great, if your numbers are less than 5 & you're feeling ok I'd say your therapy is going well.

[jbn3boys]

Personally, I am not feeling "good", so I know my therapy is not optimal. I am exhausted many days, and often can't hardly wait to go to bed. I am easily distracted, unable to concentrate, and generally feel sleep-deprived. My AHI is also often over 5. I've had a few, rare nights of 2.x, but I don't think I've ever seen 1.x. I know on the days that it is, say 3.x, I feel better. So, I am working on getting my AHI to come down. But I was just curious about any correlation.

[Bearcat]

I have paid particular attention to the AHI levels with different masks. They have a huge impact on your readings. I went from a full face mask with which I generally had AHI of 5. When I switched to Nasal Pillows, I generally can get below 1. I am sure the FF had more leaks, and different characteristics. So, while I think you need to pay attention to the numbers, realize that many factors can control your results. Even when I have routine low levels, some nights are just not meant to be and I see a level of 3 or more,

[brazospearl]

Sorry to hear you're still struggling. It sounds like you still have some investigating to do, which can be tricky when you feel like the dog's breakfast. Have you tried straight cpap mode instead of auto? I know some people to lots better with that. Might not help, but it probably wouldn't hurt to try.

[jbn3boys]

Sorry to hear you're still struggling. It sounds like you still have some investigating to do, which can be tricky when you feel like the dog's breakfast. Have you tried straight cpap mode instead of auto? I know some people to lots better with that. Might not help, but it probably wouldn't hurt to try.

I was going to try that, but instead went with a tiny range of 11 to 12. My pressures were almost always close to the 12, so I adjusted it up to 11-13. My 90% pressure is typically running at 13. But now I got a new mask to throw into the mix, so I'll have to give that a few days. Once I figure out what a good cpap pressure should be, I will probably try that. I do know that the few days that I've had "good" numbers (3-4 AHI), that I have felt better. Now if only I could replicate that on a regular basis, I may have some brain function return so I can figure all this out.

[Janknitz]

Well, JBN, I have the same machine you do, and my AHI's are consistently below 1, my averages are a very boring 0.5 almost all the time, sometimes I get "all the way up to" 0.7. And I've noticed sort of the opposite of you--it seems to me (unscientiically) that people on PR S1 autos who are doing well on therapy seem to have the lowest AHI's reported hereabouts.

There are SO many variables, but it's MHO that it's not the particular machine that makes the difference so much as the machine's settings, the mask, and your own body.

[jbn3boys]

Well, JBN, I have the same machine you do, and my AHI's are consistently below 1, my averages are a very boring 0.5 almost all the time, sometimes I get "all the way up to" 0.7. And I've noticed sort of the opposite of you--it seems to me (unscientiically) that people on PR S1 autos who are doing well on therapy seem to have the lowest AHI's reported hereabouts.

There are SO many variables, but it's MHO that it's not the particular machine that makes the difference so much as the machine's settings, the mask, and your own body.

Yeah. That gives me hope that I may one day start feeling "normal" once again!

Do you use the Resistance Control on your machine? Just curious.

[Janknitz]

Do you use the Resistance Control on your machine? Just curious.

Nope. I tried it for a few weeks and didn't notice any difference at all.

[Tielman]

You may also want to consider several other options. I was in a similar position a few months back, AHI around 5 but feeling lousy.

Here are some things to think of:

• Humidity - some need more or less than others, try varying it
  - Leak control - should be consistent, and nearly a flat line
  - Evening Rituals:
  + Do you eat near time to bed?
  + Medicine taken near bed time?
  - Check in to the following medical issues:
  + GERD issues
  + Blood Pressure medicine (if any)
  + Thyroid levels (must be a full thyroid panel, not the single test)
  + Hormone levels
  + Side effects from medicine

My resolution came with a diagnosis of Silent GERD, and adjustments to my blood pressure medicine. I now sleep on a 9" wedge, take PPI medicine and have had nights as low as .5, and don't have any of the exhaustion that I was having a few months back.

It make take time to find your "sweet spot", so don't give up, keep looking!!

[jbn3boys]

...
My resolution came with a diagnosis of Silent GERD, and adjustments to my blood pressure medicine. I now sleep on a 9" wedge, take PPI medicine and have had nights as low as .5, and don't have any of the exhaustion that I was having a few months back.

It make take time to find your "sweet spot", so don't give up, keep looking!!

How did you find out about the Silent GERD? I've never heard of that. I always thought there would be symptoms, and since I don't have any, had put it out of my mind.

Thanks for the encouragement. Some days, like today, it's just hard to want to keep going.

4. Use an oximeter and check your desats. Add at least 5L if desats are common.

I don't have an oximeter, and doubt my doctor would write a script for one. He didn't even think I had OSA. And with Christmas right around the corner, then all the new deductibles for the beginning of the year, it will likely be June before I can consider the money for one (over $100, I believe?)

Guess I'll just keep pluggin' along.

Edited to add: My concern with going with cpap at 16 is that, during my sleep study, when the pressure got up to 11, they noticed CAs, and switched me to a bilevel machine for the rest of the night (little over an hour). But my script was written for a cpap machine, not a bi-level, so I'm trying to make my autopap work for me.

[KatieW]

...
Edited to add: My concern with going with cpap at 16 is that, during my sleep study, when the pressure got up to 11, they noticed CAs, and switched me to a bilevel machine for the rest of the night (little over an hour). But my script was written for a cpap machine, not a bi-level, so I'm trying to make my autopap work for me.

It may be that a bilevel machine would work better for you. Others here have posted that cpap didn't work for them, and that bilevel did. Check with your sleep doc. Usually insurance requires that you try cpap 1st.