resMed ApneaLink - does a second night overwrite the first?

I just did one night's study with the ResMed ApneaLink (not the Plus, just the regular one). I was told that the memory in it could "hold 3 nights worth" of data, but I was looking up its specs on the manufacturer's site and it says it uses RAM (15 megs total).


I was told that for my second night, just take out the batteries, put new ones in and do the second test.

I know that with RAM, once power is removed, the data is usually wiped so this concerns me that maybe I didn't hear her correctly. Maybe she meant that the data would be overwritten for the first night.

Can anyone confirm that data recordings for two nights can be saved on this device and that putting in fresh batteries for the second night doesn't affect the first recording?

Also, if anyone knows, could you tell me HOW it retains the data without power when the batteries are removed?

Thanks so much! I have tonight, tomorrow night and Monday night open to do the second test as I have it for the long holiday weekend here (Canada Day on Monday) so I'm hoping to get at least one more test in if possible but the first one was pretty good minus the sensor killing my finger because she told me to push my finger in so far that it pinched the tip all night and I woke up a lot because of it.)

Flash memory (like what's in your SD card) is a form of RAM called NVRAM (non-volatile) that does not lose its data
when power is removed.

But I have no idea what is inside an ApneaLink or what happens when its batteries are removed.

Thanks, Jeff. I checked the specs and it just says RAM not any specific kind of RAM. Argh.

Well last night was a bust anyway since I had horrible insomnia and was staring at the walls most of the night. I think I got maybe 4 hours of sleep. I'll try to contact the company (they have an office in Australia! Yay for time zones) and do another study either tonight or tomorrow night.

If I find anything out I'll post it here for reference.

Isadora wrote:Thanks, Jeff. I checked the specs and it just says RAM not any specific kind of RAM. Argh.

Well last night was a bust anyway since I had horrible insomnia and was staring at the walls most of the night. I think I got maybe 4 hours of sleep. I'll try to contact the company (they have an office in Australia! Yay for time zones) and do another study either tonight or tomorrow night.

If I find anything out I'll post it here for reference.

Isadora, I concur with Jeff. It is likely Flash, Non-Volatile RAM. I remember from an earlier thread you indicated that the testing center said the machine could remember up to three nights of data. Replacing the batteries should not affect what's already in memory.

Looking forward to hearing what you learn from the company.

I couldn't through to the company but the center that's doing my study emailed me and said

"The ApneaLink can store several weeks of data. Removing the batteries
will not delete the previously recorded studies."

I used it again last night. Funny thing happened -- this morning maybe around I don't know, 5 am or 6 am I guess, I woke up and thought to myself, "I'm awake. I'll just shut off the ApneaLink now..." so I took off the pulse thing and shut it off. Then I WENT BACK TO SLEEP! lol I woke up later at like 7 am and thinking, "Why did I DO that??" Then I was so tired I slept some more. That's pretty funny. I even remembered to press the button on it 3 or 4 times to turn it off. Weird.

I'm going to do another one tonight just because I can and can't hurt:)

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edited to add I got an email from ResMed on this as well, and I returned the machine today and all 3 studies were saved on it:) I watched her upload them to the program on her computer. She just had to add the dates manually because like the email below says, when you take the battery out, the date and time is lost.

"Thank you for contacting ResMed.

You are correct, the apnealink can store up to 2 nights of recordings. If you remove the batteries, the time and date are lost, but the recording is still on the unit. The 15 MB averages out to around 2 nights of data. Hope this helps.

If you have any additional questions please feel free to call our Technical Support Department at 800-424-0737 option 6 then option 2."