The use of the pulse oximetric saturation/fraction of inspired oxygen ratio for risk stratification of patients with severe sepsis and septic shock

Purpose: Our aims were to determine whether the pulse oximetric saturation/fraction of inspired oxygen (S/F) can be used for the early identification of patients with sepsis who are at increased risk for death and to compare the S/F ratio with the Pao₂/fraction of inspired oxygen (P/F) ratio. Materials and Methods: This is a retrospective cohort study in 260 patients admitted to 2 tertiary mixed intensive care units (ICUs) with severe sepsis or septic shock. We studied the association between tertiles of S/F ratio and ICU mortality using Cox regression. Subsequently, we compared corresponding measurements of S/F ratio and P/F ratio upon ICU admission using Pearson correlation coefficient (r). Results: We observed an overall case fatality of 72 (28%) of 260. After adjustment for severity of the illness, the lowest tertile (S/F, <. 164) at ICU admission was associated with increased mortality (hazard ratio, 1.87 [95% confidence interval, 1.02-3.41]) comparing to the highest tertile (S/F, >. 236). The S/F ratio was correlated with P/F ratio (r = 0.48; P < .0001). Conclusion: A low S/F at ICU admission is associated with increased risk of death in patients with severe sepsis or septic shock.