Need help interpreting readings

[dboss]

Hi, new to all this and have already learned a lot by lurking here the last couple of weeks but need some advice at this point. I had my initial sleep study a few weeks ago and was diagnosed with severe apnea (45 incidents an hour including some central incidents). Doctor prescribed CPAP machine initially set at 5(Resmed Elite II and I chose Swift LT mask), which I tried for a week then went for titration study. Don't have the results of the titration yet (takes about a month!) but the technician told me she had varied the pressure from 5 to 9. Based on that and what I have learned here, I have been adjusting the pressure setting but even at pressure of 9 the readings are still high and am not sure the best way to proceed. Last night for instance I got:

Pressure setting: 9
Leak: 0.3
AI 7.6
HI 28.8
AHI 36.4

And a couple of nights ago:
Pressure: 8
Leak: 0.22
AI 10
HI 27.9
AHI 37.9

Questions:
1. What is the significance of HI very much higher than AI, is this normal?
Is it normal for AI to go down with pressure increase but HI to stay the same?
2. Based on readings like this, should I continue to increase the pressure?
3. Is the leak too high at 0.2 to 0.3 and will this affect the other readings?

Sorry for all the questions, just trying to make sense of all this...

[Wulfman]

Hi, new to all this and have already learned a lot by lurking here the last couple of weeks but need some advice at this point. I had my initial sleep study a few weeks ago and was diagnosed with severe apnea (45 incidents an hour including some central incidents). Doctor prescribed CPAP machine initially set at 5(Resmed Elite II and I chose Swift LT mask), which I tried for a week then went for titration study. Don't have the results of the titration yet (takes about a month!) but the technician told me she had varied the pressure from 5 to 9. Based on that and what I have learned here, I have been adjusting the pressure setting but even at pressure of 9 the readings are still high and am not sure the best way to proceed. Last night for instance I got:

Pressure setting: 9
Leak: 0.3
AI 7.6
HI 28.8
AHI 36.4

And a couple of nights ago:
Pressure: 8
Leak: 0.22
AI 10
HI 27.9
AHI 37.9

Questions:
1. What is the significance of HI very much higher than AI, is this normal?
Is it normal for AI to go down with pressure increase but HI to stay the same?
2. Based on readings like this, should I continue to increase the pressure?
3. Is the leak too high at 0.2 to 0.3 and will this affect the other readings?

Sorry for all the questions, just trying to make sense of all this...

Do you have a copy of your sleep study? If not, I'd strongly suggest getting one.
How many Centrals? That would be a good bit of information to know. If it was just a couple, then you may be able to increase your pressure without too much concern.
The problem with these machines is that they don't know the difference between obstructive and central events.

Your Apnea/Hypopnea numbers are high and your leak rate is borderline high.
ResMed machines tend to count Hypopneas higher than other machines. It's the Apnea numbers you want to focus on.

Are you using EPR? If so, what setting? EPR lowers your effective delivered pressure......by one centimeter per each setting. If you are using EPR, you would want to either lower the number or shut it off.....OR.....raise your pressure setting to compensate for the drop in pressure on exhale.

The pressure of 10 cm. is statistically the threshold for Centrals......although some have reported them at lower pressures and some at higher pressures.

If you continue to raise your pressure and your numbers get worse, you know you're going in the wrong direction.
If higher pressures don't lower the number of Apneas and your sleep study shows a significant number of Centrals, you'd be wise to consult with your doctor about possibly getting a Bi-Level ASV type of machine.
I do find it a bit odd that if the Centrals WERE significant, that they didn't have you do a Bi-Level titration or prescribe a special machine. The fact that they didn't, MAY suggest that they weren't significant (or your doctor is a moron).
I also find it "interesting" that the person doing your sleep study (apparently) stopped at the pressure of 9 cm. Do you have any idea why they did that? (your sleep study may hold that answer)


Den

[jules]

You need the titration results to know how low your AHI might be able to get. Even then that isn't an end number. If you had some centrals during titration even at the "best" pressure, your AHI might not be super low but it might be "acceptable" according to your doctor. That doesn't mean that you should find it "acceptable".

The doc might have been avoiding doing a bipap or fancier machine titration for many reasons. Insurance / money can be a big part of that. Get the titration study and post both the diagnostic PSG and titration and see if you can get one of the experts on the board to comment on them.

Good luck.

[dboss]

I didn't know enough to get a copy of my sleep study when I first met with the doctor. Have another appointment in a couple of weeks to get the titration results, will request copies of both studies at that time and report back here.

I am using EPR set to 3. I thought that it is the pressure on inhale that matters and the pressure drop on exhale is just for comfort and doesn't affect the readings -- are you saying that the setting of 9 is only equivalent to a setting of 6 with EPR off?

[jules]

resmed machines drop full cm for each unit of EPR on what it senses to be exhale (or some portion of exhaling) - it won't work well with low pressures - not sure where the threshold is where you don't want to use it

so 9 inhale and 6 "exhale" for setting of 9 with EPR of 3 in an ideal world

respironics user here

[dsm]

Hi, new to all this and have already learned a lot by lurking here the last couple of weeks but need some advice at this point. I had my initial sleep study a few weeks ago and was diagnosed with severe apnea (45 incidents an hour including some central incidents). Doctor prescribed CPAP machine initially set at 5(Resmed Elite II and I chose Swift LT mask), which I tried for a week then went for titration study. Don't have the results of the titration yet (takes about a month!) but the technician told me she had varied the pressure from 5 to 9. Based on that and what I have learned here, I have been adjusting the pressure setting but even at pressure of 9 the readings are still high and am not sure the best way to proceed. Last night for instance I got:

Pressure setting: 9
Leak: 0.3
AI 7.6
HI 28.8
AHI 36.4

And a couple of nights ago:
Pressure: 8
Leak: 0.22
AI 10
HI 27.9
AHI 37.9

Questions:
1. What is the significance of HI very much higher than AI, is this normal?
Is it normal for AI to go down with pressure increase but HI to stay the same?
2. Based on readings like this, should I continue to increase the pressure?
3. Is the leak too high at 0.2 to 0.3 and will this affect the other readings?

Sorry for all the questions, just trying to make sense of all this...

What I am reading into your data is that your high numbers for HIs suggests you may be prone to Complex Apnea where the pressure used to clear your obstructive apneas may cause you to have an increase in central apneas. The pressure they suggested for you was surprisingly low (the 5 Cms) & even at 9 is still by some standards a low setting, but if the doctor was worried about inducing Complex Apnea then he was making the right choice.

A timed bilevel machine can sometimes help people if they do exhibit Complex Apnea symptoms (& I am not yet at all sure this is what you have). The top-of-the-line ASV machines are really good at dealing with people who have Periodic Breathing (PB) that includes centrals. PB is when their breathing fluctuates in volume & rate in a pattern where the fluctuations are observable within a 3/4 minute window. We don't know if that is happening in your case. We would need more data to be able to tell.

As wulfman has pointed out, if raising pressure increases HI (even if AI lowers) then it looks a lot like induced Complex Apnea is emerging.

Good luck

DSM