UMEM Educational Pearls

Title: Peripheral Oxygen Saturation Facilitates Assessment of Respiratory Dysfunction in the Sequential Organ Failure Assessment Score With Implications for the Sepsis-3 Criteria.

Keywords: SOFA, sepsis, oxygen saturation (PubMed Search)

Posted: 8/25/2021 by Quincy Tran, MD, PhD (Updated: 12/26/2024)
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Background: SOFA score has been used as a predictor for poor outcomes in patients with sepsis. However, the original SOFA score utilizes PaO2/FiO2 ratio to calculate the SOFA’s respiratory component. When there are no ABG, thus no PaO2, we have to convert patients’ spO2 to PaO2, and the amount of oxygen support to FiO2 (for example, 2 liters of oxygen via nasal cannula = 0.27). This is cumbersome.

Objective: This study assessed whether spO2 can be used instead of PaO2/FiO2 ratio for SOFA’s respiratory score.

Settings: 8 hospitals across Sweden and Canada

Patients: Adults with sepsis. 19396 patients were included for the derivation group while there were 10586 patients for the validation cohort.

Study Results:

When PaO2 was not measured, assigning respiratory SOFA score of 1 for spO2 94% and respiratory SOFA score of 2 for spO2 < 90% had good discriminatory capability.
The AUROC with SOFA score using spO2 threshold as above was 0.783 (0.767-0.798), which was slightly increased from the model using previous methods to calculate respiratory SOFA scores (0.781 [0.765-0.796]).

Discussion:

For Emergency Medicine, using a cut-off threshold for spO2 of 94% (respiratory SOFA of 1) and 90% (respiratory SOFA of 2) can simplify how to calculate the SOFA score.
It’s also simpler to do research when we collect SOFA score retrospectively.

References

Valik JK, Mellhammar L, Sundén-Cullberg J, Ward L, Unge C, Dalianis H, Henriksson A, Strålin K, Linder A, Nauclér P. Peripheral Oxygen Saturation Facilitates Assessment of Respiratory Dysfunction in the Sequential Organ Failure Assessment Score With Implications for the Sepsis-3 Criteria. Crit Care Med. 2021 Aug 18. doi: 10.1097/CCM.0000000000005318. Epub ahead of print. PMID: 34406170.