adding concept for PaO2/FiO2

[mikkokotila]

ITEMID 490 and 779. The other is 'PaO2' and the other is 'PaO2 arterial'.

For FiO2 it's slightly more complicated. The ITEMID are:

[1040,
 1206,
 185,
 186,
 189,
 190,
 191,
 727,
 3420,
 3421,
 3422,
 1863,
 5955,
 2518,
 2981,
 7018,
 7041,
 7570,
 8517,
 227009,
 227010,
 226754]

This is how often each appears in chartevents:

3420      39375
190       31014
3422      16043
186         594
185         544
189         456
727          23
226754       13
227010        6
1040          3
Name: ITEMID, dtype: int64

So I'd say let's go with 3420 and 190.

Conclusion

We can add the following ITEMID concept and call it pao2-fio2

• 3420
• 190
• 490
• 779