What does the number mean on my machine?

I realize that it's a measure of the air pressure (I think?) But what unit is it measuring in? When I turn it on it starts at 5.0. When I wake up in the morning it is usually sitting on around 5.5. However sometimes if I wake up in the middle of the night it will be in the 7.0-9.5 range. I'm assuming that when I'm fully awake it should return to the starting point of 5.0 because there would be no obstruction of my airway. I'm just worried that when I wake up in the morning and it's on 5.1 that it hasn't been higher through the night and I'm not getting any air pressure. I don't have any way to see what it does throughout the night. I assume that all of that information is stored on the data card. Unfortunately, while I have the card, I don't have anything that can read the card. I assume that the medical supply store that I got the machine from has something to read the card or perhaps my doctor.

I have my second sleep study for titration at the end of this month. I wish my doctor would have explained all of this stuff to me. If anyone here can give me a simplified explanation of the mystery number and why it's so low when I wake up, I would appreciate it.

Sorry if I sound stupid but I just haven't found any information on this. I actually have a science degree

unclematt wrote:I realize that it's a measure of the air pressure (I think?) But what unit is it measuring in? When I turn it on it starts at 5.0. When I wake up in the morning it is usually sitting on around 5.5. However sometimes if I wake up in the middle of the night it will be in the 7.0-9.5 range. I'm assuming that when I'm fully awake it should return to the starting point of 5.0 because there would be no obstruction of my airway. I'm just worried that when I wake up in the morning and it's on 5.1 that it hasn't been higher through the night and I'm not getting any air pressure. I don't have any way to see what it does throughout the night. I assume that all of that information is stored on the data card. Unfortunately, while I have the card, I don't have anything that can read the card. I assume that the medical supply store that I got the machine from has something to read the card or perhaps my doctor.

I have my second sleep study for titration at the end of this month. I wish my doctor would have explained all of this stuff to me. If anyone here can give me a simplified explanation of the mystery number and why it's so low when I wake up, I would appreciate it.

Sorry if I sound stupid but I just haven't found any information on this. I actually have a science degree

I believe it's air pressure measured in cm.

You are correct, the number is CPAP air pressure. It is measured in centimeters of water (cm H2O). Machines usually run from 4.0 to 20.0 of pressure. Yours running from 5.0 to 9.5 sounds usual. Your ResMed machine displays summary data on the LCD (search for threads on this).

The fact that you are seeing the values vary the machine is probably set to APAP mode (Automatic Positive Airway Pressure). A CPAP machine is Constant Positive Airway Pressure. It gets set at one pressure. That pressure may be lower at the start if you have a 'ramping' feature.

Read the material connected to 'Our Wisdom' on top of the page. It should answer some questions and maybe give you some more to ask your doctor about.

Good luck,
Mark

Your APAP is designed to deliver different amts of pressurized air as you breathe. It calculates the pressure to be delivered based on your last five breaths, in this way, it tries to prevent your having apnea or hypopnea events. While I had a loaner APAP, it was set to begin at 4 and if necessary go to 20 (cmH20) -- the setting on your machine were detemined during the titration portion of your Sleep Study.