Contec Medical Systems CMS50E Pulse Oximeter

For obscure, work reasons I ordered a Contec Medical Systems CMS50E Pulse Oximeter from Amazon.

front view

back view

This device clips on a finger, toe, or whatever and reads how much oxygen is in your blood.

Let’s get to the bottom line:

This is a neat little gizmo.

The out-of-box is nice, starting with – really – a metal box. That is so retro!

box view

The UI is all done with 1 button. I’m impressed! Very easy to figure out and use. The OLED screen is laid out simple and clean. The options are simple and clean. No instructions are needed, though they are written in understandable, native-Chinese English.

The device’s UI flow is impeccable.

The whole thing is tightly designed and built. Hats off to whoever put the user-package together.

The PC programs are unremarkable, but they do work and are also simple and clean. There should be only one program – a subject I’ll take up in a later, technical posting.

Apparently, the device is sold to the sleep apnea market. You can clip it on your finger and record a night of Oxi percentage and heart rate at per-second intervals (no untethered waveform recording). The device alarms when the two values go out of ranges you set. The alarm is loud. This could be quite handy for some people wanting to stay alive. Given my own experience with Oxi levels at anywhere near alarming values, it’s hard to imagine someone not waking up on their own if the Oxi value is too low. Pulse monitoring might be nice. Sit up to get the heart ticking again. Anyway, what little I looked at in this whole area worked fine.

OK. What about the device?

I wanted it to measure a quick dip in oxygen level under certain, odd circumstances. Apparently, no … can … do. So, for work/research purposes, this device looks like a disappointment. We’ll see. Jury’s still out.


Here’s the deal: Maybe 20 years ago, the kids and I were prowling high up in Bel Square where a local hospital had a show-and-tell for the day. They had a finger clip thing that was supposed to read the oxygen in your blood – presumably an early pulse oximeter. I thought: “Cool. Let’s see what happens.” And held my breath for a couple minutes – until the nurse looked more than a little concerned. The number, if I recall, dropped to around 70%.

So that’s what I expected from this device, tempered by body age.

I tried to get the Oxi number down. I tried some more. I tried taking a deep breath and going 100 seconds. I tried breathing everything out and going 30+ seconds.

The results did not match memory.

It took a day of struggle to get the Oxi level below 94%. Turns out, there’s a 30 second lag from when the level is lowest in the mind, so to speak, to when it goes low on the device. And getting the level below 94 requires a breath-out hold for 40+ seconds rather than take-a-big-breath hold for a minute or two.

But that’s just me. Mark M. had no problem getting the Oxi level to drop.

That said, it’s become an interesting toy – raising all sorts of questions.

Let’s do another blog post about my “user” experience.

2 thoughts on “Contec Medical Systems CMS50E Pulse Oximeter

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