I recently purchased a personal oximeter so I can better understand how this type of device might be used in a home setting. After a little browsing around and a pointer from a colleague in the London Quantified Self group I chose the Crucial Medical Systems CMS 50E. This device is available from Amazon (although it’s listed under the brand of “Contec”) at a reasonable price (£62 / $90). It should be noted that for these sensors there is a fairly large range in pricing; the CMS 50E is in the lower-middle of the range but it is on the low end of the range for units where you can actually get the data out of the device and onto your computer (a pre-requisite for it being interesting to me).
Why did I buy this device? Well there was no driving medical reason why I needed it but rather it was mainly educational. I wanted to both understand what the products in this space looked like and learn how blood oxidation monitoring can be used. Whether or not it will be something I keep up I’m not at all convinced but I do expect to learn a lot from having tried. In this post I’ll share my initial observations on the device and I hope to follow this up in a few weeks time with some more thoughts once I’ve really had a chance to use it and learn from the process.
The CMS 50E
First Impressions
The CMS 50E is a small device (the pictures often make it look misleadingly large) and clips itself over your finger. It’s grip on your finger is strong enough that one can sleep through the night without fear of it falling off but not too tight to be uncomfortable. Having slept with it twice now I can say it’s completely functional way of recording your oxygen levels; it feels a bit awkward at first but I imagine after a few more times it will become less noticeable. Anyway, being a relatively “good sleeper” I had zero issues with falling to sleep when using this unit. The display on this unit is well done, colours are sharp and information is displayed in a reasonably straight forward and attractive manner. Clipping it onto your finger and watching the device come alive with information is fun and dare I say probably a worthy party trick for the QS-inclined. Purely unintentionally, I brought it home to a house full of guests and before I knew it everyone — children included — wanted to try it.
So, as far as first impressions go, all is well. Now it comes to actually reading the manual. I know a lot of the men in the audience will feel that that is a wholely unnecessary step reserved for those too weak to figure it out themselves. Well I can understand that mindset and yet hopefully you will believe me that trying to “just figure it out” has its limitations with this product when you get past the surface use cases. So now that we’ve got around our initial male bravado, let’s come back to the manual. It’s terrible. This is the worst case of “chinglish” I’ve seen in a long time. So yes, in a few cases I laughed but it was still quite hard to gain a real understanding of the product through it. Looking online you will be reassured to find that a lot of the chatter around the product is positive. People more qualified than myself seem to concur that the readings are very accurate. Some joke that while the manual is terrible it’s all relatively easy to figure out yourself. Really? Maybe I’ve just fallen down and hit my head and that’s why it’s so difficult. Actually, I suspect that people who are using the device for real-time monitoring find that use case very easy. It’s when you start to want to download it to your computer and analyse it that it becomes less clear.
Computer Analysis
First off, the software that comes with this is only for the PC. I use a Mac and run windows in VMWare and that works too but there is no native Mac application. Of note, there is an open source effort called SleepyHead that reads in the Contec files (it also reads in files from ResMed S9′s). Looks interesting and I have downloaded it but not used it yet. Another annoyance — that likely won’t matter to many of you — is the software is provided on one of those “mini-CD” formats that is half the height of a normal CD. As this doesn’t work on my iMac drive I had to find the software on the Internet which wasn’t a real problem. For those of you who are interested, you can find it here: [software download]. For people on Windows 7 onward you should be using V2.x of the “Sp02 Assistant”. In the V1.x software there were two programs, one called Assistant, one called Review. I’m currently unsure if the 1.x Review software is useful additional functionality but have concentrated my initial focus on just the v2.x Assistant.
The first thing you notice (see below) is the software is a blocky old school user interface design. Reminiscent of the the VB and Powerbuilder days; definitely not in the running for a “sexy application” design award.
Sex appeal aside, does it work well? Is it usable? Well in my experience it is not very intuitive at first and my experience was compounded by two annoyances:
- Wired Connection. The primary way this device connects is via a mini-USB connection but it’s not a standard cable and plugging in just any micro-USB will not work. You need to use the one that comes with the device. I guess I can live with that but I’m constantly in the pursuit of less cables in my already complicated life and so this kind of annoys me. Also for the road warrior it means one more cable to carry around with you (personally my warrior days are over). As another minor annoyance, it seems that even after you’ve connected once, you’ll need to go through the manual step of connecting each time you want to run the software. It’s not that it’s hard, it just seems unnecessary.
- Bluetooth Connection. I really shouldn’t complain here but I’m a complainer. The 50E isn’t advertised as even having bluetooth — there’s a more expensive model that does — but newer units of the device (including mine) have it thrown in for free. I guess maybe it’s a case of “you get what you pay for” but my manual has no mention of bluetooth yet my computer and 50E see each other just fine but there is a password needed to pair the devices and my ability to guess the password has met with the same success as my patience in trying to mount a brute force attack. If anyone knows what the password is I will gladly owe you beer of your choosing.
Once you get the hang of it though, there’s not too much to it and I think it does meet the right “functionally fit” bar. Being a bit of a winger I must make a few more complaints though before I conclude:
- User Profiles. There is a concept of “user profiles” which associates your Sp02 data with some reference data (name, age, gender, weight, etc.). I thought initially that this was quite easy to setup but now my data comes back from the device not associated with the profile I’ve setup. This is probably something I can figure out but seems like it’s less user friendly than it could be.
- Time. There isn’t a clock built into the device and therefore when you start “recording” you need to specify what time it is. I know it’s petty but if Amazon’s “one-click” purchase means anything than things like this must be consider anathema in user design. Yes a clock would have cost additional money … probably about a $1. Let me suggest that that would have been a $1 well spent.
As a final note I’ve included an example report from my sleep last night. Turns out I’m a rather dull sleeper but you should get a sense for what kind of information you’ll be getting in the analysis software. The software presents four reports but the results they produce overlap considerably from report to report.
