Prediction of Extubation Failure in COVID-19

Abstract

BACKGROUND:

${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ may be a reliable noninvasive alternative to the ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ index. Furthermore, the ROX index (ie, the ratio of ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ to breathing frequency) has been validated to predict high-flow nasal cannula failure in subjects under spontaneous breathing. However, these indices have not been tested in subjects with COVID-19 receiving invasive mechanical ventilation. This study aims to verify the correlation between both the ROX index and ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ with ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ and the ratio of ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ to breathing frequency, and to determine the accuracy of the indices that use ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}$ for the prediction of extubation failure in subjects with COVID-19.

METHODS:

A prospective cohort study was conducted from May 15, 2020, to June 15, 2020, with subjects with COVID-19 on invasive mechanical ventilation. Indices using ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}$ in the formula were compared to those using ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ . Additionally, the performance of the indices in predicting extubation failure was evaluated.

RESULTS:

This study included 69 subjects age 64.8 ± 14.6 y. There were no differences between the median values of the indices, including between the ROX index and ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ to breathing frequency (P = .40) or between ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ and ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ (P = .83). When comparing the ROX index with the ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ index to breathing frequency, they were found to be strongly correlated (R² = 0.75 [95% CI 0.6763–0.8152], P < .001). The comparison of ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ with ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ revealed R² = 0.70 (95% CI 0.563–0.749, P < .001). The area under the receiver operating characteristic curve for the ROX index to determine extubation failure was 0.74 (P = .01), whereas for ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ it was 0.78 (P < .001).

CONCLUSIONS:

The indices presented a good correlation in subjects with COVID-19 on invasive mechanical ventilation, and both the ROX index and ${\mathbf{\text{S}}}_{{\mathbf{\text{pO}}}_{\mathbf{\text{2}}}}{\mathbf{\text{/F}}}_{{\mathbf{\text{IO}}}_{\mathbf{\text{2}}}}$ can discriminate extubation failure in this population.