05-06-2021, 02:32 PM
Viatom/Wellue versus CMS50F Oximeters - A Comparison
I have just got a new CMS50F because it was going super cheap, and I've run it alongside the Viatom Visual Oxy (which is pretty much the same as the Viatom/Wellvue CheckMe O2 or SleepU models, the wrist-worn ones with the soft ring sensor). I hope this isn't too in-depth or unwanted, feel free to ignore it if so.
TLDR: My preference overall is for the Viatom/Wellview. but there are several reasons that might make you prefer the CMS50F.
The long story...
Cost: CMS50F is way cheaper. So if cost is an issue, and you definitely want a wrist-based product, this is probably the one.
Sensor: The Viatom ring sensor is by FAR superior IMO. It stretches significantly, it has remained intact in nearly 2 years of use off and on, and it doesn't tend to lose contact with the finger. By contrast, although the traditional duck-bill sensor with the CMS50F is a bit more reliable than the fingertip ones, I STILL had to tape it in place to stop it from falling off, and even then, it would shift around enough to lose up to 20 seconds of data at a time a few times per night.
They also have different behaviours if they do slip off your finger. The CMS50F just keeps recording until you stop it (or turn off the device) whereas the Viatom prompts you to reinsert your finger for 10 seconds (allowing you to swap fingers, for instance) before stopping the recording and powering off. You can also press the power button to skip the countdown and just save it or hold down the power to turn it off, which will also autosave it.
Recording time: Depends. Viatom has more storage space overall (40 hours in 10 hr slots) but Contec products can record up to 24 hours in one session. My biggest (and only real) pet peeve is that the Visual Oxy that I use will stop recording after 10 hours, rather than continue recording in the next slot. I believe that Crimson said to me that one of the models will continue recording into a second session if you sleep longer than that, but I'm not exactly sure which model(s) have that function.
I'm not sure how many individual sessions that the CMS50F can save (the default is 2, I think), but Viatom is fixed to four, no matter how short. So even if you have only recorded 5 minutes four times, rather than being able to use the rest of the time in a fifth slot, it will record over the oldest slot instead. I haven't done enough testing of the CMS50F to know for sure how it works. With the Viatom, though, you can of course stop the recording and restart again if you wake after a few hours and feel like you're going to sleep longer.
Comfort: Viatom. The device is smaller, lighter and more comfortable to wear. The Viatom is around 0.9-1.1oz (25-31g) whereas the CMS50F is around 1.8oz (50g). The strap is softer (and the device can be removed from it for easy cleaning) compared to the chunkier screen and traditional watch strap of the CMS50F. As above, the sensors are more comfortable, for me, for the Viatom, too.
The only minor issue is that where the Visual Oxy (not necessarily other models) slots into the strap, there's a small metal button that helps hold it in place. I'm allergic to nickel and this irritated my skin, especially being under plastic, but that was easily fixed with some clear nail polish and/or a piece of adhesive medical tape over the back of the strap where the metal sits. And by contrast the CMS50F has a metal buckle and the back of the main unit, so even more of an area for potential sensitivity.
If you also have a strong preference for which wrist to use, be aware that if you want the screen to be the right way up and the sensor port closest to your fingers, you would need to wear the Viatom on your left wrist and the CMS50F on the right. Both sensors should be long enough to be worn both ways, but if you have long hands, you may not find that possible.
Data captured: Viatom because it also includes movement sensors as well as pulse and SpO2. CMS50E has only pulse and SpO2. They both cover similar ranges of SpO2 and pulse, with similar levels of accuracy depending on environmental factors, etc.
Battery Life: CMS50F gets 20 hours, apparently, and the Viatom wrist products get 16 hours (apart from the CheckMe O2 Max, which has a 72-hour battery). In practice though, the Viatom has always allowed me to get two days worth of recordings on one charge, and it only takes an hour or so to top up.
Software: Viatom. Although the Contec software comes with some better reports, the graphics are kind of ugly, and it can be a nightmare getting the right drivers and software version on certain systems. I think Contec makes software only for PC, but as far as I can tell, it has no apps for your smartphones. Viatom makes software for the PC and Macs, plus it does have apps for both Android and iOS, and the data can be imported into OSCAR from either the computer or the smartphone. The smartphone also allows you to monitor and record your data directly to the phone via Bluetooth, although I am not sure if that data is also possible to import into OSCAR, or just the overnight sessions. However, you can't monitor your sats with the CMS50F live because of the lack of Bluetooth, and the finger probe using the USB port on the device. If you wanted to monitor or record the data live into OSCAR, you would need to use either a Bluetooth enabled Contec product or a finger clip device like the CMS50E while it's plugged in via the USB cable.
Also - one other issue currently with OSCAR is that the newer (v2.2 firmware, I think) CMS50F devices can't be accessed by OSCAR to extract the data directly. You would need to save the data using the Contec software and then upload that, instead, which is the same kind of process you have to use with the Viatom data files. Either way, it still works, it's just an extra step for now, at least.
The main problem with the Viatom software is that you can't tweak the graphs or change the zoom - it shows you a zoomed-out and a zoomed-in view of the graph, but it's fixed. However, OSCAR gives you that functionality, so it's not a huge issue. There is a bug with one measure (if you have over 250 events, it miscalculates the ODI) but that will be fixed in the next version.
Date/Time Accuracy: CMS50F but only because of the current OSCAR interface. Both products store the date and time, and can be synchronised through the software (or simply by connecting via Bluetooth to your phone for the Viatom). When it comes to synchronising your pulse ox data to your CPAP data, it's easier for the CMS50F because the import wizard in OSCAR allows you to manually set the start time to match. With Viatom, you have to currently edit the file as the start time is hardcoded in the file, and you need to be comfortable using a hex editor to do that. It's not technically hard when you know how, but it's probably a challenge for many people.
Hopefully, in future, the Viatom import tool will allow you to manually correct it. As long as your devices are all set to the same time, though, they should line up close enough, and you can also tweak the time shift for the CPAP data as well, if necessary.
Accuracy: Either. I recorded myself one night using both products, just to find this out. Overall, they were pretty much the same, as far as I could tell. There were a few glaring differences - when my finger slipped out of the CMS50F, it produced all kinds of spurious data at the extreme ends of the spectrum that was clearly inaccurate, while the Viatom seemed to be a little better at that. I did see that there were some differences where my oxygen levels were spiking and plummeting precipitously, probably to do with the frequency of data polling, but I don't know the exact figures for either product. That said, the overall accuracy is about the same. Just bear in mind that the lower your SpO2 gets, the less reliable the measurements become.
Ease of use: Viatom. Out of the box, both of them record automatically as soon as you switch it on and put your finger in. A quick press of the power button on both swaps between the time/date and showing your current pulse and oxygen levels. The CMS50F screen is bigger, has a variety of brightness options, and may be easier to read for some. The Viatom is smaller and simpler, without the colours and extra data and may be preferred for the simpler, cleaner interface.
However, the real ease of use comes in getting it to work with your computer, extracting the data, etc. Viatom has one software package for their pulse oximeters and needs no special drivers. the Contec products need specific driver versions, depending on the firmware and product, and different software and versions, same thing. On top of that, while the Viatom is simply plugged into the USB port on your PC or automatically connects through Bluetooth to your phone/tablet, there is often an issue with the correct order of plugging in the cable, the device, starting the software, rebooting your computer etc that can be endlessly frustrating for the Contec products. And as I have ALSO discovered, if you have multiple devices that use different drivers, you are a little stuffed. My old CMS50E won't communicate with the computer with the new drivers needed for the CMS50F, so bear that in mind if you have multiple devices. They also use different versions of the software, (so I currently have three separate programs from two manufacturers to get data off three different pulse oximeters. LOL) I also had to play hunt-the-data-files with the Contec products because of an issue with where the Contec software tries to save the files in Windows 10.
Alarms/Alerts: It depends. Audible alerts? CMS50F for sure. You can set the max and min thresholds for both pulse (between 0 and 254bpm) and oxygen saturation (0-100%), plus there is an audible finger-out alarm. However, it's an all or nothing. Technically you could set the boundaries to very high/low figures that you're unlikely to hit if you only want the finger-out alarm, though. It also comes with a pulse beep option, which can be set separately from the alarms. There are 4 volume settings. All settings (aside from a couple) can be set manually via the device menu.
All the Viatom watch-type devices come with vibration alarms triggered by low oxygen levels (80-95%) with the intention of waking you more gently. The intensity can be varied between 1 and 5. and turned off completely. These values must be changed through the software. The CheckMe O2 Max comes with audible alarms too, I believe.
Accessories/replacements: Both. You can get replacement finger probes and USB cables for both products, though maybe a little easier for Contec. The prices seem similar in my area but YMMV. You MUST use the USB that comes with the Viatom to access the data on your computer and for charging and though I've seen some people say you don't with the Contec products, I've never got it to work unless I use the one that came with it, either.
Reliability: Viatom. As mentioned above, the CMS50E that I had, the display became unreadable after a relatively short period of time. I now have to use my smartphone in a dark room in order to read the screen, even with it set to the maximum brightness on the device. It still works as well as it previously did (ignoring the software and driver issues) but that is a huge problem for me.
The Viatom has been much better. I was worried the ring sensor would snap really easily but touch wood, so far it hasn't. I did manage to break part of the plastic strap, but this did glue back and Viatom replaced the whole unit for me, as they don't sell replacement straps alone for my specific product, the Visual Oxy. That's really impressive considering the unit was out of warranty, but it also costs £180 or so brand new now and it was significantly cheaper when I purchased it (about half the price 2 years ago).
I did find that, with the Viatom cable, the two plastic parts that house the custom circuit board on the wider end of the USB cable tend to separate easily, and as the PCB is attached to the cable with three tiny solder joints, these can easily break if you aren't careful or are rough with it. For protection, I've wrapped a little tape around the plastic just to keep the two sides from working loose, but just be sure to never pull on the cable itself to unplug it from the computer.
Customer Service: Viatom. While there are definitely some minor issues with language with both companies, Viatom's staff have proven to be far more helpful than I ever expected. They provided me with a tool to convert the data from an older software product to allow it to be viewed in their new one, there was the above-mentioned help with the strap (and they actually apologised that they couldn't give me either just a strap separately, or a brand new product, only a refurbished one - while letting me keep the existing one too). They clarified some of the details about how their product works and calculates the statistics and they've always been endlessly polite. Sometimes the response time has been a little slow, but they've always resolved my issues for me.
I found that Contec support was a lot less helpful. They don't seem to be much use at figuring out the program version/driver version/etc issues, at least in my experience. I've had two CMS50Es, both of which has issues with connecting to the computer to download the data (which defeats the whole purpose). The first one ended up dying after a year - the screen was just black, it would stay on permanently until the battery ran out but didn't seem to be recording or measuring any data. The second one wouldn't connect at all to my laptop when it was updated to windows 8 and I simply used it for live on-the-spot measurements rather than recording overnight. Although it was barely a year old, Contec refused to exchange it, even after such a fundamental failure in the first one, and never managed to get the software working on my laptop after I upgraded, so I moved onto Viatom instead.
Overall conclusion: Viatom, is (IMO) the better device overall, especially if you want a slimmer, lighter product, up to 40 hours of data in four sessions, a more comfortable and reliable finger sensor, Bluetooth, smartphone apps and/or Mac software, no fussing around with drivers or software versions and more reliability long term.
However, if you want to record up to a maximum of 24 hours total in one or more sessions, budget is important, you want/need audible warning alarms or a bigger screen, you're only using a PC and you're not worried about capturing/monitoring data in real-time, the CMS50F may well do everything that you need.
TLDR: My preference overall is for the Viatom/Wellview. but there are several reasons that might make you prefer the CMS50F.
The long story...
Cost: CMS50F is way cheaper. So if cost is an issue, and you definitely want a wrist-based product, this is probably the one.
Sensor: The Viatom ring sensor is by FAR superior IMO. It stretches significantly, it has remained intact in nearly 2 years of use off and on, and it doesn't tend to lose contact with the finger. By contrast, although the traditional duck-bill sensor with the CMS50F is a bit more reliable than the fingertip ones, I STILL had to tape it in place to stop it from falling off, and even then, it would shift around enough to lose up to 20 seconds of data at a time a few times per night.
They also have different behaviours if they do slip off your finger. The CMS50F just keeps recording until you stop it (or turn off the device) whereas the Viatom prompts you to reinsert your finger for 10 seconds (allowing you to swap fingers, for instance) before stopping the recording and powering off. You can also press the power button to skip the countdown and just save it or hold down the power to turn it off, which will also autosave it.
Recording time: Depends. Viatom has more storage space overall (40 hours in 10 hr slots) but Contec products can record up to 24 hours in one session. My biggest (and only real) pet peeve is that the Visual Oxy that I use will stop recording after 10 hours, rather than continue recording in the next slot. I believe that Crimson said to me that one of the models will continue recording into a second session if you sleep longer than that, but I'm not exactly sure which model(s) have that function.
I'm not sure how many individual sessions that the CMS50F can save (the default is 2, I think), but Viatom is fixed to four, no matter how short. So even if you have only recorded 5 minutes four times, rather than being able to use the rest of the time in a fifth slot, it will record over the oldest slot instead. I haven't done enough testing of the CMS50F to know for sure how it works. With the Viatom, though, you can of course stop the recording and restart again if you wake after a few hours and feel like you're going to sleep longer.
Comfort: Viatom. The device is smaller, lighter and more comfortable to wear. The Viatom is around 0.9-1.1oz (25-31g) whereas the CMS50F is around 1.8oz (50g). The strap is softer (and the device can be removed from it for easy cleaning) compared to the chunkier screen and traditional watch strap of the CMS50F. As above, the sensors are more comfortable, for me, for the Viatom, too.
The only minor issue is that where the Visual Oxy (not necessarily other models) slots into the strap, there's a small metal button that helps hold it in place. I'm allergic to nickel and this irritated my skin, especially being under plastic, but that was easily fixed with some clear nail polish and/or a piece of adhesive medical tape over the back of the strap where the metal sits. And by contrast the CMS50F has a metal buckle and the back of the main unit, so even more of an area for potential sensitivity.
If you also have a strong preference for which wrist to use, be aware that if you want the screen to be the right way up and the sensor port closest to your fingers, you would need to wear the Viatom on your left wrist and the CMS50F on the right. Both sensors should be long enough to be worn both ways, but if you have long hands, you may not find that possible.
Data captured: Viatom because it also includes movement sensors as well as pulse and SpO2. CMS50E has only pulse and SpO2. They both cover similar ranges of SpO2 and pulse, with similar levels of accuracy depending on environmental factors, etc.
Battery Life: CMS50F gets 20 hours, apparently, and the Viatom wrist products get 16 hours (apart from the CheckMe O2 Max, which has a 72-hour battery). In practice though, the Viatom has always allowed me to get two days worth of recordings on one charge, and it only takes an hour or so to top up.
Software: Viatom. Although the Contec software comes with some better reports, the graphics are kind of ugly, and it can be a nightmare getting the right drivers and software version on certain systems. I think Contec makes software only for PC, but as far as I can tell, it has no apps for your smartphones. Viatom makes software for the PC and Macs, plus it does have apps for both Android and iOS, and the data can be imported into OSCAR from either the computer or the smartphone. The smartphone also allows you to monitor and record your data directly to the phone via Bluetooth, although I am not sure if that data is also possible to import into OSCAR, or just the overnight sessions. However, you can't monitor your sats with the CMS50F live because of the lack of Bluetooth, and the finger probe using the USB port on the device. If you wanted to monitor or record the data live into OSCAR, you would need to use either a Bluetooth enabled Contec product or a finger clip device like the CMS50E while it's plugged in via the USB cable.
Also - one other issue currently with OSCAR is that the newer (v2.2 firmware, I think) CMS50F devices can't be accessed by OSCAR to extract the data directly. You would need to save the data using the Contec software and then upload that, instead, which is the same kind of process you have to use with the Viatom data files. Either way, it still works, it's just an extra step for now, at least.
The main problem with the Viatom software is that you can't tweak the graphs or change the zoom - it shows you a zoomed-out and a zoomed-in view of the graph, but it's fixed. However, OSCAR gives you that functionality, so it's not a huge issue. There is a bug with one measure (if you have over 250 events, it miscalculates the ODI) but that will be fixed in the next version.
Date/Time Accuracy: CMS50F but only because of the current OSCAR interface. Both products store the date and time, and can be synchronised through the software (or simply by connecting via Bluetooth to your phone for the Viatom). When it comes to synchronising your pulse ox data to your CPAP data, it's easier for the CMS50F because the import wizard in OSCAR allows you to manually set the start time to match. With Viatom, you have to currently edit the file as the start time is hardcoded in the file, and you need to be comfortable using a hex editor to do that. It's not technically hard when you know how, but it's probably a challenge for many people.
Hopefully, in future, the Viatom import tool will allow you to manually correct it. As long as your devices are all set to the same time, though, they should line up close enough, and you can also tweak the time shift for the CPAP data as well, if necessary.
Accuracy: Either. I recorded myself one night using both products, just to find this out. Overall, they were pretty much the same, as far as I could tell. There were a few glaring differences - when my finger slipped out of the CMS50F, it produced all kinds of spurious data at the extreme ends of the spectrum that was clearly inaccurate, while the Viatom seemed to be a little better at that. I did see that there were some differences where my oxygen levels were spiking and plummeting precipitously, probably to do with the frequency of data polling, but I don't know the exact figures for either product. That said, the overall accuracy is about the same. Just bear in mind that the lower your SpO2 gets, the less reliable the measurements become.
Ease of use: Viatom. Out of the box, both of them record automatically as soon as you switch it on and put your finger in. A quick press of the power button on both swaps between the time/date and showing your current pulse and oxygen levels. The CMS50F screen is bigger, has a variety of brightness options, and may be easier to read for some. The Viatom is smaller and simpler, without the colours and extra data and may be preferred for the simpler, cleaner interface.
However, the real ease of use comes in getting it to work with your computer, extracting the data, etc. Viatom has one software package for their pulse oximeters and needs no special drivers. the Contec products need specific driver versions, depending on the firmware and product, and different software and versions, same thing. On top of that, while the Viatom is simply plugged into the USB port on your PC or automatically connects through Bluetooth to your phone/tablet, there is often an issue with the correct order of plugging in the cable, the device, starting the software, rebooting your computer etc that can be endlessly frustrating for the Contec products. And as I have ALSO discovered, if you have multiple devices that use different drivers, you are a little stuffed. My old CMS50E won't communicate with the computer with the new drivers needed for the CMS50F, so bear that in mind if you have multiple devices. They also use different versions of the software, (so I currently have three separate programs from two manufacturers to get data off three different pulse oximeters. LOL) I also had to play hunt-the-data-files with the Contec products because of an issue with where the Contec software tries to save the files in Windows 10.
Alarms/Alerts: It depends. Audible alerts? CMS50F for sure. You can set the max and min thresholds for both pulse (between 0 and 254bpm) and oxygen saturation (0-100%), plus there is an audible finger-out alarm. However, it's an all or nothing. Technically you could set the boundaries to very high/low figures that you're unlikely to hit if you only want the finger-out alarm, though. It also comes with a pulse beep option, which can be set separately from the alarms. There are 4 volume settings. All settings (aside from a couple) can be set manually via the device menu.
All the Viatom watch-type devices come with vibration alarms triggered by low oxygen levels (80-95%) with the intention of waking you more gently. The intensity can be varied between 1 and 5. and turned off completely. These values must be changed through the software. The CheckMe O2 Max comes with audible alarms too, I believe.
Accessories/replacements: Both. You can get replacement finger probes and USB cables for both products, though maybe a little easier for Contec. The prices seem similar in my area but YMMV. You MUST use the USB that comes with the Viatom to access the data on your computer and for charging and though I've seen some people say you don't with the Contec products, I've never got it to work unless I use the one that came with it, either.
Reliability: Viatom. As mentioned above, the CMS50E that I had, the display became unreadable after a relatively short period of time. I now have to use my smartphone in a dark room in order to read the screen, even with it set to the maximum brightness on the device. It still works as well as it previously did (ignoring the software and driver issues) but that is a huge problem for me.
The Viatom has been much better. I was worried the ring sensor would snap really easily but touch wood, so far it hasn't. I did manage to break part of the plastic strap, but this did glue back and Viatom replaced the whole unit for me, as they don't sell replacement straps alone for my specific product, the Visual Oxy. That's really impressive considering the unit was out of warranty, but it also costs £180 or so brand new now and it was significantly cheaper when I purchased it (about half the price 2 years ago).
I did find that, with the Viatom cable, the two plastic parts that house the custom circuit board on the wider end of the USB cable tend to separate easily, and as the PCB is attached to the cable with three tiny solder joints, these can easily break if you aren't careful or are rough with it. For protection, I've wrapped a little tape around the plastic just to keep the two sides from working loose, but just be sure to never pull on the cable itself to unplug it from the computer.
Customer Service: Viatom. While there are definitely some minor issues with language with both companies, Viatom's staff have proven to be far more helpful than I ever expected. They provided me with a tool to convert the data from an older software product to allow it to be viewed in their new one, there was the above-mentioned help with the strap (and they actually apologised that they couldn't give me either just a strap separately, or a brand new product, only a refurbished one - while letting me keep the existing one too). They clarified some of the details about how their product works and calculates the statistics and they've always been endlessly polite. Sometimes the response time has been a little slow, but they've always resolved my issues for me.
I found that Contec support was a lot less helpful. They don't seem to be much use at figuring out the program version/driver version/etc issues, at least in my experience. I've had two CMS50Es, both of which has issues with connecting to the computer to download the data (which defeats the whole purpose). The first one ended up dying after a year - the screen was just black, it would stay on permanently until the battery ran out but didn't seem to be recording or measuring any data. The second one wouldn't connect at all to my laptop when it was updated to windows 8 and I simply used it for live on-the-spot measurements rather than recording overnight. Although it was barely a year old, Contec refused to exchange it, even after such a fundamental failure in the first one, and never managed to get the software working on my laptop after I upgraded, so I moved onto Viatom instead.
Overall conclusion: Viatom, is (IMO) the better device overall, especially if you want a slimmer, lighter product, up to 40 hours of data in four sessions, a more comfortable and reliable finger sensor, Bluetooth, smartphone apps and/or Mac software, no fussing around with drivers or software versions and more reliability long term.
However, if you want to record up to a maximum of 24 hours total in one or more sessions, budget is important, you want/need audible warning alarms or a bigger screen, you're only using a PC and you're not worried about capturing/monitoring data in real-time, the CMS50F may well do everything that you need.
) but I kept the O2 Ring on until shortly after our short conversation. This was reflected in my data by an end to the CPAP waveforms and a corresponding rise in my pulse rate until the point when I took off the ring shortly afterwards. That correspondence has given me some confidence in the level of synchronisation achieved.
