AHI Skewed down

[mhjunk525]

   

I'm sure it has been discussed before, but during my search for a decent night's sleep I found that either Oscar or Resmed skews your AHI down. 

I have an odd waking breathing pattern.  Deep breath in, hold it, breathe out slowly.  Due to this, it has been difficult to figure out what is going on with me, my sleep, and my CPAP.  People say ignore the waking apneas it is 'wake-sleep garbage'.  For most this is true, but my breathing while awake is always coded with numerous apneas.  This holds true on low pressure, high pressure, and no pressure (Sleep study).  My waking respiration rate averages about 7.

I sleep great when I sleep; Resp rate ~17 with a low AHI.  If I wake up even a little, my events shoot up and the pressure on my CPAP runs towards the max.  This usually wakes me fully and I have to turn off the machine and try again. While looking at all these wakes, turn off, ramp ups, I discovered that events are not counted while in ramp.  Makes sense as most have 'wake-sleep garbage' to tend to.  What doesn't make sense is that the entire time is used in the AHI formulas, including the ramp time.  So during times of ramp, 0 events are recorded but the time is counted.

Likely it won't affect many greatly, but if you have long ramp periods with many unscored events, you are doing worse than you are lead to believe.

I have attached an image that shows the math. For me, this one session (while awake) shows an AHI of 42.69.  If the ramp period is removed from the calculation (which it should be) than the AHI is actually 100.91.  That’s a pretty big difference if you ask me.

[cdplatt]

Don't use the machine for diagnosing awake breathing patterns. It's not designed for that. Suggest you turn off the ramp - for most, it isn't helpful. If pressure is shooting up while you're waking up a little, suggest you post full images from OSCAR to see if forum members can make suggestions to mitigate the issue.