Question about masks

[Joe Bezz]

Maybe someone can shed some light on this! I am using a ResMed10 auto machine in APAP mode. 

When I use the ResMed N30i nasal mask my AHI’s are between .5 and 1.0 

When I sleep with the Philips DreamWear Nasal mask my AHI goes up to between 1.0 and 2.0 

None of the settings are changed while using either mask. Anyone have any idea why this might be?

Thanks in advance for your replies!

[CorruptAlligator]

You will notice that different masks feel different in terms of volume of air moved inside the coupler (the part of the the mask that couples to you air inlet, nose, mouth, et...). For example, nasal pillow has a direct coupling with very minimal area before coupling to the nostrils. Nasal mask has a large area (the portion of the mask) that couples to the nose. The nasal pillow will be much more effective in delivering airflow at the same pressure level. Larger the mask area at the same pressure level, the pressure with be less effective in delivering air. You'd likely have to raise the pressure.

So the lesson is, different mask designs changes how the air is delivered to you, and in return you responds differently in AHI. And pressure is just a machine setting, but external factors influence airflow in different ways like the masks.

So, when you change masks. It makes sense to understand the differences with the same pressure, and try adjusting the pressure to compensate for the new mask (this part is quite complex).

For me personally, I am sensitive to strong airflow so I cannot use P10. It tends to wake me up when airflow changes, and P10 is most noticeable of all masks due to it's direct coupling and strong flow. But also, full face masks are not all that effective for me. So the happy medium for me are the nasal masks.

[Joe Bezz]

I've been using the DreamWear Nasal mask for the last 3 nights instead of the ResMed N30i. Both are close in design but I have noticed to exhale ports on the DreamWear mask allow a lot more air to escape! I have up'ed the max pressure but my AHI is still double with the DreamWear mask as opposed to the ResMed N30i.

[Crimson Nape]

Since the Dreamwear has a larger exhaust port, I'm guessing your increase in events are probably CAs.  If I'm correct, it is because an increase in venting will wash out more CO₂.

[Gideon]

The amount of air/CO2 should be the same for both masks. The one with the largest Vent would result in less rebreathing of CO2 and as such lower CO2 concentration and a higher probability of Central Events.

[Joe Bezz]

Is it suggested I raise the Max Pressure a bit to see if it helps with the increase of Central Apenas?

[OpalRose]

It always helps if you would post an OSCAR chart, preferably two charts that reflect the difference in the masks.