Welcome to the forum. I'll try to answer your questions but I do encourage you to download
OSCAR and post the nightly charts. There is much we can see at a glance of those charts that we would never see with a verbal description.
Your machine is a
ResMed AirCurve 10 VAuto. This is considered to be a BiLevel machine.
You are in Mode "
S" or
Spontaneous which means you initiate your breathing "spontaneously" without help from the VAuto. You can think of this a "Manual" mode.
In "S" mode you have two basic settings,
EPAP and
IPAP, both of which are
fixed and will NOT change over the night.
PS or
Pressure
Support is simply the difference between IPAP and EPAP pressures.
VAuto mode.
Settings
Min EPAP. the lowest pressure that the machine will use, also the starting pressure.
Max IPAP. the highest pressure the machine will use. You may or may not reach this pressure
PS. This is a fixed setting. It is added to the current EPAP to determine the current IPAP. It is still the difference between EPAP and IPAP
Jumping to your 3rd question.
Sort of. ResMed devices, VAuto included, respond to obstructive events to increase pressure, in this case, the active EPAP pressure. The first 'event' it detects is the Flow Limit, the smallest of the obstructive events and when detected increases the active EPAP pressure. The algorithm also responds to hypopneas and obstructive apneas. The theory is that by responding to the flow limits your machine can increase pressure and thus prevent future obstructive events. After a period of time with no events, including flow limits the pressure will decrease. IPAP follows EPAP by the amount of the PS always being only that much higher.
So the machine doesn't know or sense what your needs are but instead just reacts to events.
Question 2.
apparently, the machine did not 'need' to increase pressure to head off very much. With more 'events' it would have maxed out.
Should you use VAuto mode? We tend to favor an Auto mode. BUT I'd like to see at least detailed summary data on your doctor's settings before recommending a change. Detailed OSCAR charts would be better. What I want to check out is the specific makeup of the events that occurred with your doctor's settings. I am thinking that the added events are mostly central as that seems to follow what you describe. But I could be wrong and the answer would impact my setting suggestions.