I am a bit of a geek so when I started CPAP I downloaded the card daily so I could get to understand what this thing was doing.
Now I think I have a good handle on it and my 5 day average AHI is stable under 2 with the 95% pressure 5 day average stable I only download the card when the numbers change on the machine screen. That's about once every 3 or 4 months and there is no option for that in the poll....
I just got started in the CPAP world, but so far I've been downloading to Sleepyhead about every 3 days.
As I'm only about 3 months into this journey, I'm still downloading the data daily. I take the SD card out of the machine, and immediately lock it. I then soon look at and download the data using both ResScan and Sleepyhead. I also make an entry in a (text file) sleep log, where I record the date. the sleep time, the AHI, and a few remarks. As I am always wearing some device on my back to avoid back-sleeping, I record the particular thing I used, mention if leaks seemed a little hi, etc. I find that if I delay much in putting down the impressions of the night, my memory starts to fade/blur. I may decide to back off the download frequency after a while, but it has been so valuable to see the hi-res flow data and the other stats and graphs, that probably won't happen for some time yet.
I should mention that I purchased spare 2GB SD cards (while such are still available), and I alternate using the original ResMed card and one of the Sandisk spares as the card to put back in the S9. That way, if a card goes bad or is damaged, I still have (most) of the data, if needed. Of course, I always have a daily backup of the SD card itself. The last thing I do before re-inserting a card in the S9 is to unlock it. That way, all the cards are locked at all times, unless actually in the S9.
If anyone else wants to purchase spare SD cards, I would suggest not waiting long. The original spares I bought in January were less than $7 each. I bought more just this past week, when I noticed that the price has about doubled. As others have reported difficulties in using the more modern, higher-capacity SD cards (like SDHC or SDXC types), I didn't want to try that, even tho it is currently cheaper to purchase some of these than the original type. In the computer business, that usually signals that the older/smaller/slower/whatever product is being phased out. I really didn't want to wait until the only source of an SD card was to buy a replacement from ResMed. When that happens we will see a truly amazing escalation in the price.
I said weekly because it was the closest to when I do it - which is when I remember it. My AHI averages in the mid 3s. When I look at the graphs the average is driven by the periods that I am awake and on the hose. You know those periods when you wake up in the middle of the night and can't get back to sleep. Also, having a cat that wakes you at 5:30 doesn't help matters when you try to get back to sleep. :grin:
When I first started with CPAP, I was looking at the data daily. Nowadays, I have settled into a routine whereby the data is pretty much the same night after night. If there is some sort of "event" that makes me curious, I will download that morning. Otherwise, I tend to go a month or two at a time between downloads.
Yeah, I know: boringly optimal treatment is a problem other people should have too.
I generally download weekly, however a few weeks back I inadvertently forgot to replace the SD card in the machine and only realised a week later when I wanted to download data before traveling interstate. Thinking I'd lost the data for that period of time I just reinserted the card, traveled and then uploaded when I came back home. I was surprised to learn that the S9 had kept data locally and then copied that data to the card maintaining my stream of data intact so I had not lost any days. My Rescan software information is complete with all data.
Not sure what the issue is with "skewing" that I saw earlier in the thread, but if the S9 is storing data locally to copy to the card, then that may cancel out the safety mechanism of using multiple cards that are reformatted each time.