There are myriad reasons why SpO2 should be used in preference to PaO2 to assess oxygenation in critical illness...
This link gives a nice overview
https://emcrit.org/pulmcrit/pulse-oximetry/
This link gives a nice overview
https://emcrit.org/pulmcrit/pulse-oximetry/
Comments
I ask trainees what would happen to their PaO2 if they hold their breath for a minute...
https://journal.chestnet.org/article/S0012-3692(15)46490-6/abstract
Would a VBG and SpO2 not suffice?
I've got a real soft spot for this study comparing VBG and ABG in patients with COPD:
https://thorax.bmj.com/content/71/3/210
We talk about correlation between ABG and VBG and how the only real difference is PaO2
https://litfl.com/vbg-versus-abg/
Well for me (working in a non-cardiac unit) the most common reason would be to calculate the PaO2/FiO2 ratio.
But even for this, there is some nice work showing that SpO2/FiO2 can be used to impute this calculation...
https://pubmed.ncbi.nlm.nih.gov/19242333/
I don't think there is justification to do an arterial stab for an ABG if the critical care patient does not have an arterial line (for another reason), VBG is much more comfortable for the patient and provides adequate information.
Think before you tell me the PaO2....
https://bsky.app/profile/iainmoppett.bsky.social/post/3lbtjmci7ys2g
And for most patients in AECOPD the issue is not hypoxemia (or hypoxaemia as need be to promote cross cultural understanding)
As long as one is not particularly worried (=has a low pre test probability), SpO2 is ok