can mask affect AHI?

My AHI has increased and I'm not sure why. Back in Oct & Nov it was mostly 2.4 to 2.9 (with a few days at 1.9-2.2). I'm prescribed a pressure of 7 and since I wanted to get more of those lower AHI days, I tried changing to a pressure of 7.5 about 3 weeks ago. I started a new mask at that time too, the Flexifit 431. My AHI was about the same with the new pressure and mask, ranging from 2.5-3.1, so pretty much no change.

I couldn't use the Flexifit every night until I got Padacheeks, and my old Comfortgel leaked too bad on 7.5, so I went back to a pressure of 7 for a few days.

On the 8th I went back to 7.5 and my Flexifit mask. The 2nd night my AHI went to 4.2 and has gone as high as 5.5 since. My leaks are fine according to the machine, so I don't know what's going on. I can't figure out why 7.5 and the Flexifit were fine the first time I tried it, but now my AHI is doubling. Any thoughts?

well, I've just had, and maybe still got, problems with leaks between the hose and my humidifier fitting so you could check that on the off chance. or maybe your mask is a bit unstable at times so you could try adding a band across it somewhere to hold it steadier.

Everything effects AHI, masks and how we use each one for sure. I started with the Comfortfull, then tried the Flexfit 431, the 431 had close to the same mask leak rate and if felt better, except for slipping around the last half of the night. The downside my AHI was better with the ComfortFull, so I went back with it. There was only a change in AHI of 2 or three, but after three days of the higher AHI, I could feel being more tired. Jim

It's easy to make changes too fast, if you do you won't be able to really sort out causes and effects.

Yeah, I think I did too much changing around at once. I just wanted to get away from the Comfortgel mask so badly I couldn't wait to switch! I love the Flexifit but it immediately felt like there was less air inside the mask, if that makes sense. Like there was just air swirling around in there not doing anything.

I'm also having trouble really knowing what's going on because I don't have the card reader yet, but at least I know I will be able to get one in a few weeks. Relying on the LCD display pretty much blows.

I've noticed that with every mask I use and i've used about 6 of them or more, I have a different AHI ranging from 0.2 to 2.9, also the leak rate is different on all of them so the main thing to figure out and get fixed is the leaks, if you can track them down, you will more than likely get a lower AHI. Keep us posted on what you find!

SNM

Definitely in my experience also. I love the Swift II, but find although the Mirage Activa is heavier & more cumbersome, I get 0 to .05 AHI compared to about 1.8 with the Swift. Think it's a seal thing, but just a hunch.

Crazy! I honestly had no idea masks could affect the AHI like they do. This CPAP stuff has a definite learning curve.

My AHI with the comfortgel nasal mask is about 2.5, but it hurts me like hell to wear it. I swithced to a mirage quattro a few days ago and my AHI is now 6, but no pain at 3AM on my face. I am assuming its all about leaks (which I am working on).

stacia123 wrote:Crazy! I honestly had no idea masks could affect the AHI like they do. This CPAP stuff has a definite learning curve.

It's pretty logical, really. These machines determine AHI and other events based on "air flow", so anything that happens to change the air flow could affect the event detection.


Den

My experience with perceived level of air pressure and type of mask:

-Full face mask: less perceived air pressure being delivered (and I think it takes a higher pressure to achieve the same AHI due to so much surface area of the mask)

-Nasal mask: more perceived air pressure being delivered (the mask has a smaller area in which the air is being delivered so I feel it more)

-Nasal pillows: most perceived air pressure being delivered (the nasal pillows have a small opening so the air seems to be delivered at a higher rate)

I think of it much like water coming out of a hose. If you put your finger over the end of the hose, it narrows the stream of water and the water then seems to be at a much higher pressure than if the water is just running out of the hose.

Maybe we have an expert here who can let us know if the pressure is actually increased due to a smaller delivery device.

gasp wrote:My experience with perceived level of air pressure and type of mask:

-Full face mask: less perceived air pressure being delivered (and I think it takes a higher pressure to achieve the same AHI due to so much surface area of the mask)

-Nasal mask: more perceived air pressure being delivered (the mask has a smaller area in which the air is being delivered so I feel it more)

-Nasal pillows: most perceived air pressure being delivered (the nasal pillows have a small opening so the air seems to be delivered at a higher rate)

I think of it much like water coming out of a hose. If you put your finger over the end of the hose, it narrows the stream of water and the water then seems to be at a much higher pressure than if the water is just running out of the hose.

Maybe we have an expert here who can let us know if the pressure is actually increased due to a smaller delivery device.

Except.....that the airflow is monitored at the machine (inside it). Once the "circuit" (humidifier, hose and mask) are filled with air, the machine's sensors monitor the amount of pressure it's trying to push out and decides whether to increase or decrease it and based on the variations tries to determine what events are occuring.

Den

stacia, does your machine have a place to input the type and brand of mask?? If so, that may be one reason you're seeing the changes.

Kajun

TXKajun wrote:stacia, does your machine have a place to input the type and brand of mask?? If so, that may be one reason you're seeing the changes.

Kajun

Her profile shows that she's using a Respironics M Series Pro. Only the ResMeds have that mask selection feature (at least between the two "R" companies it's the only one).

Den

Wulfman wrote:

gasp wrote:My experience with perceived level of air pressure and type of mask:

-Full face mask: less perceived air pressure being delivered (and I think it takes a higher pressure to achieve the same AHI due to so much surface area of the mask)

Except.....that the airflow is monitored at the machine (inside it). Once the "circuit" (humidifier, hose and mask) are filled with air, the machine's sensors monitor the amount of pressure it's trying to push out and decides whether to increase or decrease it and based on the variations tries to determine what events are occuring.

Purely anecdotally, of course, it feels like I have less air blowing on my face with the Flexifit than I do with the Comfortgel. I did wonder if the machine had a set flow rate no matter what mask is used, but if the machine is monitoring air flow and adjusting accordingly, then I'm sure it's just my perception.