Spo2 availability in mimic iii

[anishtamboli17]

so in our preliminery analysis of data availability, we checked for spo2 values in our neonatal sepsis cohort.
We referred the first day abg code and used
646 -- SpO2
220277 -- O2 saturation pulseoxymetry as our main itemids.
The result count was however 0.
So is this because of missing data or a mistake on our part ?
What would be the best source for oxygen saturation values in neonates