Help on A.H.I. Readings

I have been running a pressure of 9 for a couple of months with an A.H.I. of around 1.5. Recently I decided to try an oral appliance. I was told the appliance will not eliminate CPAP in my case but could reduce the pressure. My pressure is not high but I would prefer to reduce it if possible.
So following the doctor's suggestion I used the appliance along with the CPAP to see if I could become accustomed to it and more importantly to see the effect on the A.H.I. The appliance is awkward to say the least but the A.H.I. was reduced to near zero with the CPAP still at a pressure of 9.0. Before doing another sleep study my doctor suggested reducing the pressure to 7 to see the effect. Well last night my A.H.I. shot up to 11.4 but of that my OAI was only 1.4 so my HI was 10.0 . This is only one night but I've never seen a reading like that and would appreciate any feedback you may have on the readings. Thanks !

I should have mentioned that my leak rate is low.

The pressure of 7 seems to keep your airway open just enough to stop apneas. The pressure isn't enough to totally stop blockages, leaving you with an HI of 10. If it were me, I would have dropped the pressure to 8.5 or 8 first to see what happened. The oral appliance doesn't look to promising to me.

Brenda

it would be very difficult to measure AHI with the machine even at minimum 4cm pressure. You would probably find at the lowest 4cm that you would not be getting enough air to breathe normally.

If you could tolerate 5cm or maybe 6cm pressure (lowest possible pressure), you could put the machine in straight cpap mode and it should record events seen yet not respond to them. That way you could get an idea how well the dental device is working. Even that method is not really accurate because it doesn't take much pressure to influence how you may respond.

Normally, you would have to under go another PSG to test the dental device to make sure it was doing its job. If you have not exhausted all your PSG studies for the year, insurance usually pays for the follow-up study.

Then you have before and after PSG studies to confirm the device is effectively treating your disorder. You don't want to find out 5yrs from now that all along the device has not been working and overworking your heart to a point of failure, by then it is a little late. If you are going through all the expense, discomfort and hassles of getting used to the device you want to be sure it is working. If the PSG shows your AHI is below 5 and normal sleep is restored you may not need the cpap at all.

If I were going to use an autopap at a single pressure for the primary purpose of seeing what the data shows, I think I'd keep it in auto mode and simply set the minimum and maximum pressures to the same number, like 8 for the min and 8 for the max, or whatever single number you want to use.

I'm not sure, but I think that would be the only way to get the autopap to use a single pressure, yet still look at ALL the same things it had been looking at previously...and possibly even look at them in exactly the same way. I don't think putting it in cpap mode would allow it to look at flow limitations. It would mark apneas and hypopneas in either mode, but just to be sure there was no difference in the way it "looked" at them, I'd keep it in auto mode and simply set the min and the max for the same single number. Might not make any difference which mode was used for a single pressure, but that's the way I'd do it.

Thanks for the excellent observations and suggestions. Last night I set it for APAP with the min and max both at 8.0 and the results were good.
I am going to play with the settings over time and try an APAP range which is how I started months ago before switching to straight CPAP. I switched because I found the change in pressures over the course of the night woke me up but I'm more accustomed to the machine now. I expect to have a follow up study in April or May so no matter what conclusions I reach now it will all have to verified in the study.

I'd welcome any other insights or suggestions. Thanks mucho.