Fingertip oximeters - which finger?

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masticator
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Fingertip oximeters - which finger?

Post by masticator » Sat Jun 19, 2010 8:40 pm

Which finger should be used to measure the blood oxygen concentration with a fingertip oximeter? Should it make a difference?

We are getting widely varying values [of about 10%] depending on if the index or middle fingers are used. Obviously operator error is one thought going on here.
Does left or right hand matter? And advice on achieving the best results?

Thank you.

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WearyOne
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Re: Fingertip oximeters - which finger?

Post by WearyOne » Sat Jun 19, 2010 9:07 pm

At the doctor's office whenever mine is checked, they always use the index finger. And when I had an overnight home pulse/oximeter test, the instructions said to use the index finger. But I honestly don't know if it makes that much difference or not.

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torontoCPAPguy
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Re: Fingertip oximeters - which finger?

Post by torontoCPAPguy » Sat Jun 19, 2010 9:08 pm

My manual says to use the index finger. I use the middle finger if I am really ticked.

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torontoCPAPguy
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Re: Fingertip oximeters - which finger?

Post by torontoCPAPguy » Sat Jun 19, 2010 9:12 pm

My manual also says that one must be still when taking reading by the way. At night, when I am recording, I use masking tape (the green or blue type to make it easy to get off cleanly) to keep the oximeter on well. Otherwise, when exercising I simply hold my arm up against my chest to make sure the finger and the meter are still. One must remember that while these units are amazing pieces of Chinese electronics they are not the precision oximeters that we in the USA design and have them make for us at ten time the price.

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BigAn
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Re: Fingertip oximeters - which finger?

Post by BigAn » Sat Jun 19, 2010 9:26 pm

Any finger will due as long as there is no nail polish, in that case put it on sideways. Also keep in mind that some individuals have poor periphal circulation and in that case your hands are cold and none of the fingers may give a reliable reading.

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dave21
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Re: Fingertip oximeters - which finger?

Post by dave21 » Sat Jun 19, 2010 10:28 pm

I always use the index finger, that's what the doctors/hospitals and instruction manuals recommend. There's also some school of thought that when checking blood pressure and pulse that it should be from your left hand because it's closest to your heart in terms of blood going around the body, but I never know quite if that's a fable or not. I tend to do either and don't see a lot of different.

Thanks
Dave

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happysleeper
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Re: Fingertip oximeters - which finger?

Post by happysleeper » Sun Jun 20, 2010 8:38 am

And advice on achieving the best results?
Hi Masticator,

I'm a registered nurse and have taken many oximetry measurements. The reason that the manual suggests using your pointer finger is that there is value in getting the measurement from a consistently accurate source. Staying with the same finger, if you have not done the test to follow to ascertain that more than one finger is accurate, ensures that if you get a different measurement on that same finger, it's truly a difference in blood oxygen saturation, not just a difference in circulation to the finger tested. Every person's anatomy is different, so right or left hand, pointer or middle, doesn't matter; consistency of good quality measurements is what is important so that you can trend your values and correlate them with changes in air flow, masks, mouth leak stopping efforts, etc.

If I don't get an immediate oximetry measurement on a patient's pointer finger, I look to see which finger, toe, earlobe gives the highest reading. The oximeter can't read higher than how much oxygen is actually in the hemoglobin, so the highest value that can be read is thought to be the most accurate. To ensure that the reading is accurate, I also assess that there is no fingernail polish, which can skew the light being read by the oximeter, and hence the measurement value, and since I have the opportunity, that their blood hemoglobin level is in normal limits.

Here's a suggestion:

The next time that you're at your physician's office, have them take your oximetry measurement to establish a baseline accurate measurement. They probably have a sturdier oximeter which is regularly monitored for accuracy. See if you can reproduce their measurement with your oximeter. This will establish the accuracy of your oximeter. Remember which finger you tested.

Then test your other fingers with your oximeter. The fingers that have the same measurement as the first finger, assessed in the same general time frame (such as getting the measurement within 10 seconds or so after starting the reading), can then be used as your alternate measurement fingers, so that you don't get sore fingers, and you'll be reasonably sure that you're getting an accurate measurement.

Have fun,

Happy Sleeper

masticator
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Re: Fingertip oximeters - which finger?

Post by masticator » Sun Jun 20, 2010 1:27 pm

Thank you all very much for your considered input. Happy Sleeper, great idea to check against the doctor's office - that idea had escaped me. LOL torontoCPAPguy.

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Re: Fingertip oximeters - which finger?

Post by greg-g » Mon Jun 21, 2010 4:09 am

Just to be different, I use my middle toe. I find it a lot more comfortable and the results look identical after your toes warm up. It's the middle of winter down here and it can take up to 20 minutes to get sensible readings on a cold night.
I did cut about 1 cm of rubber from the top of the probe to make it fit.

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