Sleepyhead Pressue and EPAP graph

[Rainsey]

Hi all,

Been using Sleepyhead on a MAC for a while now and only now just trying to get my head around things due to my therapy going a bit haywire.


Background . Have a Philips Dreamstation Auto CPAP, great little machine. My question is in regards to the Pressure / EPAP graph in Sleepyhead.

The pressure I assume is the actual pressue that the CPCP unit is pumping out. I understand that EPAP is Expiratory Positive Airway Pressure and I think I understand that it is a positive pressure on expiration. The graphs that I see in Sleepyhead are two almost identical traces but the EPAP is at a lower pressure.

What I am having trouble getting my head around is that if the Pressure is the output pressure of the machine and the EPAP is the pressure applied at exhalation, how is it that they are identical traces with exception of amplitude. Can someone out there actually explain the correlation between the two?

Kindest Regards
Rainsey

[Crimson Nape]

Hi Rainsey -

You have one of the Flex options turned on. This option will reduces your exhale pressure by a set amount. This aids in reducing flow limitations and improving tidal volume.

[OpalRose]

Here is a brief description of the Flex settings:

Flex settings 1, 2, and 3 for PR machines.
You can receive up to 2cm pressure relief, which is flow based.

• C-Flex – Provides pressure relief upon exhalation.
• A-Flex/C-Flex+ – Provides pressure relief taking place at the end of inhalation and at the start of exhalation.

I usually use AFlex setting at 1.  Most of the time, I will see an exhale pressure of 2cm less than the Ipap pressure, and sometimes it will be closer to 1cm drop regardless of the setting.  This is based on flow.

[Rainsey]

Hi Rainsey -

You have one of the Flex options turned on.  This option will reduces your exhale pressure by a set amount. This aids in reducing flow limitations and improving tidal volume.

Hey, thanks for the prompt reply. Yep you are correct, I have A-flex and have it set to 3, for no real scientific reason. But this does not really answer my question perse' and this is probably more due to my naivety with Sleepyhead.

i understand the fact that by turning on Flex the exhilation pressure drops, it is a brilliant feature. Probably what I am asking, possibly incorrectly, is the pressure graph in Sleepyhead shows the pressure and the EPAP pressure. I would expect the pressure to actually be one line not two, as the actual pressure of the unit is always on, but varied dependant on the cycle of my breathing.

So where I am ultimately confused is that in any single point of time Sleepyhead is showing two pressure measurements. In reality there cannot be two different pressures at any single point of time.

My sincere appologies for probably the silly question but I can get my head around all the other data coming out of Sleepyhead, just not this one!

Kindest regards
Rainsey

[jaswilliams]

Ok I understand what your asking. The pressure graph only shows ipap (inhale pressure) and epap (exhale pressure)

Due to the way the flex setting works or EPR on a Resmed machine the ipap and epap are always approximately in step but separated by the amount of relief. This is the way the machines send the data to the SD card. The mask pressure chart should display how pressure is changing on a breath by breath basis.

[Rainsey]