Tattoos may stop Apple Watch from working

[udx]

 

 

 

those things are so cool....   i had to buy one a couple of months ago to keep an eye on my oxygen levels......   I smoked pretty heavily for a good number of years 30 years ago...   and I'm starting to pay a price for it.  Anyway when I get some kind of lung infection, or allergies kind of bad, my O2 levels drop down to the low 90's.  My doctor wants me to check it now and then to make sure it doesn't ever get down below 87....

 

When I get over the infection it goes up to 96-97 which is just kind of OK.....        Interestingly, my big toe checks about three to four % higher than my fingers.   No one can tell me why that I've talked to, .......    and pleast don't ask me why I know......   I'm dangerous when I get bored.

Gravity. If you want to check my hypothesis, stand on your hands for awhile and then re-check...

 

Actually there is a different more scientific explanation.

 

You first have to understand how the pulse oximeter works. The pulse oximeter works by shining infrared light through the finger or toes and measuring the amount of light that pass through (not absorbed) by the hemoglobin in the blood. It calculates the value of oxygen saturation base on the amount of infrared light is absorbed. The more oxygen rich blood the more light is absorbed. However light absorption also depend on the path the light has to travel, since toes are usually thicker than one's fingers, it would result in higher absorption of light compare to fingers leading to a higher reading of oxygen saturation.

 

I can't think of an explanation where gravity would play a role in oxygen saturation unless circulation is poor due to compression of body parts, but this would lead to lower oxygen saturation in lower body parts.

 

It does shine the light through, but that light is actually a misture of red light and infrared light and it figures out the oxygen content by the difference in how much of the two colors are absorbed......    so the thickness of the toe should really not make a difference.....   and I usually check it along with my blood pressure while laying down so they are at approximately the same level....    I thought it might have something to to with the nails

 

It does have to do with different scattering of tissue in toes and fingers. The oxygen content is by the ratio of how these light are absorbed. Even a fat finger and a thin finger would show different level of oxygenation. Pulse oximeter is not very accurate at measuring exact oxygen content, but it is good enough at measuring heart rate by the cyclical rise and fail of absorbance of light in blood.

 

http://www.howequipmentworks.com/pulse_oximeter/

[other one]

It isn't the amount of light that is absorbed and the site you quote is rather symplified.

 

The both  red and infrared light is shined on the finger......    the total amount of light that goes through the finger or toe isn't the measurement.   The tool looks at the amount of light going through the finger and adjusts the gain to calibrate itself......     the actual measurement is the ratio of how much infrared light is absorbed compared to the plain red light.....    if your finger is larger, then both frequences of light are blocked about the same by the thickness..... however, it is the color of the blood that makes the difference as to how much the infrared is absorbed..

 

I would agree that it isn't all that accurate, but a good quality tool gives someone with COPD a good idea of how well his/her lungs are doing each day, and lets one know when one should be seeing a doctor.

[The_Patriot21]

Simple (to answer earlier question) blood flows down hill easier then up. To get to the arms it has to pump up then down to the fingers, while its all downhill to the feet-and the oxygen stays with it easier. In any case I'm probably wrong I'd go with the scientific approach lol

[udx]

It isn't the amount of light that is absorbed and the site you quote is rather symplified.

 

The both  red and infrared light is shined on the finger......    the total amount of light that goes through the finger or toe isn't the measurement.   The tool looks at the amount of light going through the finger and adjusts the gain to calibrate itself......     the actual measurement is the ratio of how much infrared light is absorbed compared to the plain red light.....    if your finger is larger, then both frequences of light are blocked about the same by the thickness..... however, it is the color of the blood that makes the difference as to how much the infrared is absorbed..

 

I would agree that it isn't all that accurate, but a good quality tool gives someone with COPD a good idea of how well his/her lungs are doing each day, and lets one know when one should be seeing a doctor.

Hmm...looks like you haven't read that site or content of my post. You are basically repeating what I just said about ratio. I have made one of this device before with LED circuit board and the works, the site is more than adequate at providing what you need to construct such a device.

If your finger is larger, the scattering of light would be different at different frequencies, you would need to recalibrate it, therefore you cannot use the device to compare oxygen saturation between different body parts.

[udx]

Simple (to answer earlier question) blood flows down hill easier then up. To get to the arms it has to pump up then down to the fingers, while its all downhill to the feet-and the oxygen stays with it easier. In any case I'm probably wrong I'd go with the scientific approach lol

Blood vessels are sized in such a way that oxygenation should be relatively the same regardless height relatively to the heart like irrigation channel. The height and gravity has nothing to do with oxygenation, the amount of oxygen consumption along the path blood travel does. The further away from the heart (more oxygen consumed) the less oxygen there would be in the blood at that point, because all the intermediate vessels that consume oxygen along the way. If there are no tissue supported by the blood flow, then it doesn't matter how far away, oxygen saturation would still be the same. 

 

Oxygen diffusion is not affected by gravity.

[The_Patriot21]

Like I said I'm probably wrong. But it sounded good. Perhaps I should go into politics?