Contec CMS50IW issues

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forest
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Contec CMS50IW issues

Post by forest » Fri Jul 25, 2014 11:38 am

Hello,

I just recieved a Contec CMS50IW pulse oximeter. I don't think it works. Maybe I'm wrong.

Below is a study of me holding my breath for 1:05. I realize there is some latency in saturation decreasing, but I was under the impression it was about 15 seconds. I see no movement at all. The perfusion index was about 10% during the study. Thoughts?

Image

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Slartybartfast
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Re: Contec CMS50IW issues

Post by Slartybartfast » Fri Jul 25, 2014 11:50 am

I agree. Holding one's breath for a minute should show up as oxygen desaturation. I can get SPO2 on my CMS50 to go down to about 82% before I start seeing spots.

BTW, your pulse rate (green) is a nice example of the mammalian diving reflex, http://en.wikipedia.org/wiki/Mammalian_diving_reflex although it's supposed to be triggered by cold water contacting the face.

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palerider
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Re: Contec CMS50IW issues

Post by palerider » Fri Jul 25, 2014 11:56 am

forest wrote:Hello,

I just recieved a Contec CMS50IW pulse oximeter. I don't think it works. Maybe I'm wrong.

Below is a study of me holding my breath for 1:05. I realize there is some latency in saturation decreasing, but I was under the impression it was about 15 seconds. I see no movement at all. The perfusion index was about 10% during the study. Thoughts?

Image
it takes a good bit longer than 15 seconds for the o2 drop to get from my lungs to my fingertip when I've done it.

I held my breath as long as I could, and about the time I gave up, the o2 sat started to drop.... ymmv. batteries not included. void where prohibited and other disclaimers.

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HoseCrusher
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Re: Contec CMS50IW issues

Post by HoseCrusher » Fri Jul 25, 2014 12:02 pm

Various types of breathing seem to display different results on the oximeter.

For example if you prepare for holding your breath by hyperventilating you will see very little drop in O2%.

The best way to "simulate" sleep breathing is to sit down and relax. Using shallow breathing you will find that you can stabilize your hear rate after about 15 - 20 minutes. Your O2 levels will also tend to drop a little. At the end of an exhale, don't inhale. I don't know if you will be able to last for a full minute but your graph should be a lot different.

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SpO2 96+% and holding...

forest
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Re: Contec CMS50IW issues

Post by forest » Sun Jul 27, 2014 9:32 am

I'll try the shallow breathing method, but I really do have a feeling the oxymeter is the problem. It's strange, because it really nails the heart rate and pulse graph, so I know it's not a hardware issue. Additional evidence is that it really never moves overnight (same straight line) which was not true of my sleep study.

Bizarre.

HoseCrusher
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Re: Contec CMS50IW issues

Post by HoseCrusher » Sun Jul 27, 2014 3:55 pm

If possible you can do a side by side comparison with another oximeter to see if there are differences. Your friendly fire department may be able to offer some assistance with this. If you have a blood pressure machine bring it along too and check it out. Their equipment is usually in very good shape and abnormalities quickly show up.

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Mask: Brevida™ Nasal Pillow CPAP Mask with Headgear
Additional Comments: Machine is an AirSense 10 AutoSet For Her with Heated Humidifier.
SpO2 96+% and holding...

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palerider
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Location: Dallas(ish).

Re: Contec CMS50IW issues

Post by palerider » Sun Jul 27, 2014 4:07 pm

forest wrote:I'll try the shallow breathing method, but I really do have a feeling the oxymeter is the problem. It's strange, because it really nails the heart rate and pulse graph, so I know it's not a hardware issue. Additional evidence is that it really never moves overnight (same straight line) which was not true of my sleep study.

Bizarre.
you don't mention in your profile whether you're a person that's likely to wear nail polish, but it's *possible* that if you've got colored nail polish on the finger you're using the oximeter on, it may be blocking some of the light and causing abnormal readings.

they work by shining infrared and red light through your finger and measuring the changes in transmissivity between the two wavelengths that are caused by the spo2 in your blood.

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forest
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Re: Contec CMS50IW issues

Post by forest » Mon Jul 28, 2014 4:26 pm

Fascinating, I haven't worn nail polish since my college years, but I'll definitely try to test different fingers and compare with another device. Thanks.

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Todzo
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Re: Contec CMS50IW issues

Post by Todzo » Tue Jul 29, 2014 5:24 am

forest wrote:Hello,

I just recieved a Contec CMS50IW pulse oximeter. I don't think it works. Maybe I'm wrong.

Below is a study of me holding my breath for 1:05. I realize there is some latency in saturation decreasing, but I was under the impression it was about 15 seconds. I see no movement at all. The perfusion index was about 10% during the study. Thoughts?

Image
Many times at my desk I have tried the experiment of simply doing a simple exhale (in stride with my current breathing rate) and stopping at the end of the exhale for thirty seconds. No real change occures in the SpO2 level during the breath hold or the thirty seconds proceeding. Sometimes increases, most times stays same, sometimes decreases perhaps two percent.

I practice eucapnic breathing looking at such things as a non-stuffy nose, non-plumped veins on the back of my hand (hand near heart level), nice warm feet, and inaudible heart beat holding my hand over my ear. My breathing is often considered shallow by my personal trainer although she agrees that the heart rates for exercise levels and pulse oximiter reading show that the job is being done well.

No doctor has ever even attempted to explain the very rapid desaturations that occur due to obstructions during sleep when asked after presenting the evidence as gathered above as well as the ability of some to hold their breath under water for as much as twenty two minutes and twenty two seconds while maintaining consciousness. It seems to be more of a stress reaction with perhaps some metabolistic changes rapidly occurring due changing from a hypocapnic (metabolism frustrated) to a hypercapnic (metabolism not frustrated) state.

I am not at all surprised that holding your breath for a minute causes little change.
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