What's the point?

SleepyEyes21 wrote: Hi raftergirl - maybe I should say ' the way I understand it from how it is explained in the manual.'
Thanks for the clarification!

90% Pressure - During any given night, the device recognizes the 90% Pressure achieved by the Auto Algorithm.
90% Pressure is defined as the pressure at which the device spent 90% of the session time at or below. For example,
if the device recognized airflow for 10 hours, and 9 hours were spent at or below 11 cm H 2 O, and 1 hour was spent
above 11 cm H 2 O, then the 90% Pressure would be 11 cm H 2 O. This screen displays the average of these individual
nightly values of 90% Pressure over a 7 day and 30 day time frame (provided the device has at least 7 or 30 days
of data respectively). If the device has only 5 days of data to use for the calculation, the 5 day average value will be
seen under the 7 day display. This screen only displays if the device was set to Auto-CPAP therapy.

which part is confusing?

palerider wrote:

SleepyEyes21 wrote: Hi raftergirl - maybe I should say ' the way I understand it from how it is explained in the manual.'
Thanks for the clarification!

90% Pressure - During any given night, the device recognizes the 90% Pressure achieved by the Auto Algorithm.
90% Pressure is defined as the pressure at which the device spent 90% of the session time at or below. For example,
if the device recognized airflow for 10 hours, and 9 hours were spent at or below 11 cm H 2 O, and 1 hour was spent
above 11 cm H 2 O, then the 90% Pressure would be 11 cm H 2 O. This screen displays the average of these individual
nightly values of 90% Pressure over a 7 day and 30 day time frame (provided the device has at least 7 or 30 days
of data respectively). If the device has only 5 days of data to use for the calculation, the 5 day average value will be
seen under the 7 day display. This screen only displays if the device was set to Auto-CPAP therapy.

which part is confusing?

Hey PR - let me see if I can explain my understanding with this F**!#@ migraine... I interpreted this to mean that if the pressure reading was say an '8,' that this meant the pressure the user was at for 90% of the total sleeping time, was an '8.' Like Pugsy mentioned - I forgot the 'or below' part that many people do.

Hmmm - this leads me to another question: In the first sentence of the manual description, it states "session time." In the second sentence, it states "recognized airflow." If someone uses ramp (like I do), would the 90% pressure feature record air flow measured at either awake or sleeping times? And can the 'awake' air flow be recorded at a higher level than the user's recommended max titration rate for sleeping? (sorry if I am confusing you - I just finished reading robysue's blog )

SleepyEyes21 wrote:Hmmm - this leads me to another question: In the first sentence of the manual description, it states "session time." In the second sentence, it states "recognized airflow." If someone uses ramp (like I do), would the 90% pressure feature record air flow measured at either awake or sleeping times? And can the 'awake' air flow be recorded at a higher level than the user's recommended max titration rate for sleeping? (sorry if I am confusing you - I just finished reading robysue's blog )

the older machines don't have any sense of whether you're awake or asleep, so they figure you're asleep, and behave accordingly.

there are no awake vs asleep settings

palerider wrote:

SleepyEyes21 wrote:Hmmm - this leads me to another question: In the first sentence of the manual description, it states "session time." In the second sentence, it states "recognized airflow." If someone uses ramp (like I do), would the 90% pressure feature record air flow measured at either awake or sleeping times? And can the 'awake' air flow be recorded at a higher level than the user's recommended max titration rate for sleeping? (sorry if I am confusing you - I just finished reading robysue's blog )

the older machines don't have any sense of whether you're awake or asleep, so they figure you're asleep, and behave accordingly.

there are no awake vs asleep settings

LOL (can you tell my brain is whacked with robysue's statistics and migraine meds?)

Okay - now I think I know why my pressure keeps showing at my max titration rate each day (it's all that oxygen ingestion that I get when awake ) So again - what is the point of this feature if we don't know what actual rate we are using at any given time?

SleepyEyes21 wrote:

palerider wrote:

SleepyEyes21 wrote:Hmmm - this leads me to another question: In the first sentence of the manual description, it states "session time." In the second sentence, it states "recognized airflow." If someone uses ramp (like I do), would the 90% pressure feature record air flow measured at either awake or sleeping times? And can the 'awake' air flow be recorded at a higher level than the user's recommended max titration rate for sleeping? (sorry if I am confusing you - I just finished reading robysue's blog )

the older machines don't have any sense of whether you're awake or asleep, so they figure you're asleep, and behave accordingly.

there are no awake vs asleep settings

LOL (can you tell my brain is whacked with robysue's statistics and migraine meds?)

Okay - now I think I know why my pressure keeps showing at my max titration rate each day (it's all that oxygen ingestion that I get when awake ) So again - what is the point of this feature if we don't know what actual rate we are using at any given time?

Not understanding what you are saying here. You shouldn't be at your highest pressure when awake since you should not be having obstructive events while awake. And the 90% number is NOT what you are at most of the time. It is at *or below* that number 90% of the time.

This number is only good for trends. We use the software to see the nightly data with the graph of pressure all night, the events, how they are spaced, how long they were, etc.

SleepyEyes21 wrote:Okay - now I think I know why my pressure keeps showing at my max titration rate each day (it's all that oxygen ingestion that I get when awake ) So again - what is the point of this feature if we don't know what actual rate we are using at any given time?

just so I know I'm answering what you're asking...

what's the point of what feature? are we still talking about the 90% number?

if so, the point is that it's a reasonable number for high pressure needed, skipping small time spikes.

much like in the olympics where they throw out the highest and lowest judges marks before they total up the score.

palerider wrote:

SleepyEyes21 wrote:Okay - now I think I know why my pressure keeps showing at my max titration rate each day (it's all that oxygen ingestion that I get when awake ) So again - what is the point of this feature if we don't know what actual rate we are using at any given time?

just so I know I'm answering what you're asking...

what's the point of what feature? are we still talking about the 90% number?

if so, the point is that it's a reasonable number for high pressure needed, skipping small time spikes.

much like in the olympics where they throw out the highest and lowest judges marks before they total up the score.

Ok - I see what you and zoocrew are saying - that makes sense - ty

It's common in statistics to want to discard the "outlying" data. The world's tallest man is 8'3" tall. You might say you need to build all doors 8'3" tall. However, you'd probably stop and think that a 6'3" high door will accommodate 95% of the people and just go with that.

Suppose your APAP does a maximum of 18 cmH2O, but a 95% number of 16. You want to try a fixed pressure. You could just go to 18, but if you set it to 16, 95% of the night, your apnea "fits through the door." You may be more comfortable at 16 than at 18.

It's not an exact science, but a percentile like this is an easily calculated single number mathematical measure that gives you a good "rule of thumb." It's probably a good idea to look at the data, and results after the change. If you spent almost all the night at 8, and then jumped up to 16 for 5% of the night, you might not want to use 16 even though it's the 95th percentile number.