higher the EPAP higher the AHI - can someone explain?

[bhavintu79]

hi folks

I could not understand the rationale behind the below numbers I am seeing on my PAP machines. I have 2 different machines

Machines
* Aircurve VAuto 10 Bipap
* Airsense ASV 10 Adapto Servo Ventilator

Here are the numbers i see
* Bipap with Min EPAP: 10, Pressure Support: 9 - AHI of 33.44 - all mostly Clear Airway (CA) events
* Bipap with Min EPAP: 8, Pressure Support: 6 - AHI of 3.8 - both Clear Airway (CA) and OSA events
* ASV with Min EPAP 8.4, PS of 6 to 16 - AHI of 0.2

Questions
* What is the reason for the clear airway events to be so high when i increase pressure support and min epap on my bipap machines
* The ASV so much better than the Bipap with respect to AHI - it tends to force a breath when it detects no inspiration even for a few seconds. While it shows up with a low AHI, it does at the same time feel a bit uncomfortable - especially when i try to breathe slower. It almost enforces a certain pace of breathing and does not allow even the slightest deviation from that faster pace


Any insights from your experiences will be useful

[OpalRose]

Without seeing the actual data, it's hard to say why...

Just looking at what you posted, BiLevel with PS 9 is excessive, and may cause a higher than normal CA count.  Notice the difference when using PS 6?  

The increase in Obstructives is probably because you also lowered the minimum Epap from 10 to 8.  Epap is what sprints the airway open and prevents OA's.  

As stated, without seeing the actual charts for each setting used, and the results overall, it's hard to give exact advice.

Use the lower PS and set trigger to High or Very High.  Keep minimum Epap at 10 as long as there are Obstructives.

Please use OSCAR.  Follow the links in my signature line to guide you in posting a chart or two here.  

Also, an ASV would be the correct machine for anyone who suffers with Central Apnea.