BT_SQ 1.6 Oximetry

There have been a couple of posts on this topic before, but as we were talking about oxygen, I thought it might be worth revisiting.

Here is a comprehensive review of the sources of error with pulse oximetry, following a discussion of the principles. See the link to the CinderHK page below for more information on good references.


Slightly off topic,  though I think fascinating, here is a picture of the absorption spectrum of different contaminants of glass. The glass used in long distance telecommunication fibre optic cables is ultra pure. The signal is transmitted in the IR spectrum, at about 1.5μm, such that the attenuation of the signal is only 0.2dB per km! I took this photo at the Hong Kong Science Museum.

BT_SQ 1.6 Describe the methods of measurement applicable to anaesthesia, including clinical utility, complications and sources of error in particular:

  • Oximetry
  • Plus heaps of others 😉

Pulsatile venous flow may cause an over estimation of SpO2                              TRUE/FALSE

The red:IR absorption modulation ratio (R) equals 1 at SpO2 85%                      TRUE/FALSE

Intravenous injection of indocyanine green causes a transient reduction in SpO2   TRUE/FALSE

The accuracy of SpO2 in humans has not been calibrated below 70%               TRUE/FALSE

Red nail polish is likely to cause inaccurate SpO2 readings                                  TRUE/FALSE

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