SPO2/FiO2 as a predictor of high-flow nasal cannula outcomes in children with acute hypoxemic respiratory failure: A retrospective study

Abstract Background: High-flow nasal cannula (HFNC) is a useful treatment modality for respiratory distress in children, as it provides effective oxygenation and reduces the work required for breathing. This study aimed to determine whether the oxygen saturation to fraction of inspired oxygen ratio (S/F) is a better predictor of HFNC outcomes than the arterial oxygen partial pressure to fraction of inspired oxygen ratio (P/F) in children with acute hypoxemic respiratory failure (AHRF).Methods: This study included children treated with HFNC for AHRF between April 2013 and March 2019 at the Severance Children’s Hospital in Korea. HFNC failure was defined as the need for mechanical ventilation due to worsening respiratory distress, whereas HFNC success was defined as the improvement of respiratory distress. We analyzed trends in S/F and P/F during HFNC oxygen therapy. A nomogram was constructed based on predictive factors identified via univariate analysis, and was externally validated using independent data.Results: A total of 139 patients with arterial blood gas data were included in the S/F and P/F analysis. There was a good correlation between S/F and P/F (P<0.001). The S/F at HFNC initiation was <230 and showed a high prediction accuracy for HFNC failure (area under the receiver operating characteristic curve: 0.751). Univariate analyses identified S/F <230 at HFNC initiation, S/F <200 at 2 h (odds ratio, 12.83; 95% confidence interval, 5.06-35.84), and hemato-oncologic disease (odds ratio, 3.79; 95% confidence interval, 1.12-12.78) as significant predictive factors for HFNC failure. These factors were used to construct a nomogram, which was shown to be highly predictive of HFNC outcomes; the concordance index of the exploratory and validation groups were 0.765 and 0.831, respectively.Conclusions: S/F may be used as a predictor of HFNC outcomes. Our nomogram with S/F for HFNC failure within 2 h may be used to prevent delayed intubation in children with AHRF.