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#76008 23/01/21 8:30 PM
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Visionary
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Hi all
hope you are bearing up in these difficult times.
At Royal London we have had a new issue occur with Spo2 readings being 10% higher than those from a blood gas sample.This obviously gives the nurses a false confidence that the patients spo2 is higher than it really is.
This only appears to be happening on dark skinned patients on one particular ward. The readings have been compared to other stand alone Spo2 monitors.
The ward in question also happens to be the ward where we have been using the new Mindray N15 monitors for the longest period. My questions are:
Has anyone else seen this issue, and if so what was the solution?
Can Spo2 sensor LED's gradually wear out over time with continuous use?

We are trying some other new probes to see if that makes any difference, but any suggestions will certainly be considered.

Thanks

Richard
Lead Technologist Royal London ACCU


Richard Aldridge
Lead Technologist
Adult Critical care unit
Royal London Hospital
Whitechapel Road
London E1 1BB
Tel 0203 59 40302
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I have seen deterioration on probes due to clinell wipes leaving a residue on the sensor. Might be worth suggesting or trying single patient use probes, certainly for the long term patients?


30 years since the Chernobyl disaster and yet we still have no super heroes or zombies.
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Super Hero
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I have never heard of an LED wearing out (unless "failing" also counts) ... but lenses can become scratched, "fogged" or otherwise compromised - as with a residue as Dustcap has suggested.

When you say "continuous use" do you mean continuously on the same patient?

When you compared with other monitors ... what did you find? Were those results within expected limits?

I seem to recall that SpO2 monitors in general would be notorious for over-estimating on dark skin; but 10% sounds a bit high (I think that 2% was regarded as typical). But I would expect that - even using the latest types - results may vary between the various technologies (algorithms, interpretations of R-curves).


If you don't inspect ... don't expect.
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Up to 10% differences?
Worth a read:
Link to Article

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Ive heard of LED wavelength drift. The comments in the article below are worth a read.

https://24x7mag.com/medical-equipme...pment/understanding-spo2-sensor-testing/

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Yes, there are some great comments there. Here are just a couple that I noticed:-
Quote
In my opinion it is far better you spend your time doing these checks than doing yet more meaningless and pointless electrical safety testing…
Quote
Standards are often written with the benefit of hindsight available at the time they were written. Standards are the lowest common denominator that we should work to, but not be needlessly restricted by.
But those comments are now six years old. Have Fluke (or anyone else's) SpO2 "analyzers" moved forward to incorporate Lightman (Geoff Mathews) capabilities ... namely, to test for accuracy?

I believe that "LED wavelength drift" is really to do with temperature.

By the way, the “Medical Equipment Quality Assurance book" cited in one of the comments is still available for download if you use the infamous Wayback Machine.

Lastly (although aimed at light sources), Zeiss does a nice piece on LEDs.


If you don't inspect ... don't expect.
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Sage
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We face same condition here. It's due to IR/RED LED deteorated performace with the passage of time. Check type of led used, ceramic or plastic type. Ceramic leds tend to work for longer times as compared to plastic type. Others experts in this group may share their experience more than me.
Thanks and best of luck.
Try disposable sensors and then verify.


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