What happened? did my cpap failed to respond?

[ezdrifler]

Last night I was using my cpap from about 10pm , and I vaguely remember waking up half awake and taking my mask off since it was uncomfortable, next thing I know is 5:30 time to wake up and I realize my mask was off and has been off since 2:30... (is discouraging).

Today I got home eager to see if I can find out what happened last night (see attached sleepyhead screenshot)




And I noticed my AHI is below 5 which is good for me, I did have a few Hypos but noticed that I had nothing but one obstructive Apnea event that lasted about 12 seconds, right after that is when I woke up and took my mask off, probably because I felt suffocated...

My only concern is... the CPAP machine did not kick up.. it stayed at the minimum pressure of 5...

My understanding is that the purpose of the CPAP machine is to detect these events and immediately send help to open the airway.

Am i missing anything?

[PoolQ]

A couple of things. None of the machines can supply enough pressure to open an airway that is already closed. It hopes to splint and open airway so it will not collapse. if the airway closes anyway the machine should increase pressure after the airway opens to try and prevent the next one from happening at the higher pressure. then after a while of no events the machine will step the pressure back down and repeat the cycle if required.

If the machine detects a flow limit then it will also raise the pressure because that can be a precursor to an apnea.

"to detect these events and immediately send help to open the airway." nope. these machines do not have enough pressure to blow up a balloon.

Now ASV machines do have a little more pressure and will increase the pressure during an event to try and trigger you to start breathing.

[OpalRose]

The detail to the left of graphs shows your medium pressure at 8.20 and 95% pressure at 10, so it didn't stay at 5.

Your pressure graph is only opened up to show aprox. 1 minute of time, from 2:20 to 2:21am and that time doesn't show on the event graph, and since you had mask off pressure wouldn't change.

[ezdrifler]

Thank you for taking the time to help me understand how this machine works.

Your replies are very helpful.

[vsheline]

APAP and standard Bilevel Auto machines watch for snoring and Flow Limitation and try to avoid obstructive apneas by raising the pressure before obstructive apneas and hypopneas occur. After an apnea or hypopnea has ended, the occurrence and perhaps duration of the hypopnea or obstructive apnea will also affect how much the pressure will be adjusted.

But I think it is not so much that standard 'PAP machines can never supply enough pressure to open a closed airway. Rather, only 'PAP machines having a "backup respiration rate" (an extremely expensive feature) will raise the pressure during an apnea.

Standard APAP and Bilevel APAP machines generally are designed to wait until the apnea has ended before making any adjustment to the pressure.

Bilevel machines with a backup rate (ASV or ST or ST-A or AVAPS, etc) will automatically start cycling between the exhale pressure and a higher inhale pressure to do for us some or all of the work of breathing, which can successfully treat central apneas, and will also help in preventing obstructive events.

[Sleeprider]

Any data, that close to your awakening is not reliable. Looks pretty bad, but it's just moments before you get out of bed.

[Ghost1958]

A PRS1 machine responds like this.
It will respond to each FL. It will respond to each snore.
It will respond to one Hypop.
It wont raise pressure in response to a single OA. It will raise pressure in response to TWO OA in a certain time period tjough id have to look and see exactly how long that period is.

Looking at that graph your machine shouldnt have raised pressure in response to that one lone OA.