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. 2022 Dec;10(24):e15546.
doi: 10.14814/phy2.15546.

Reduced oxygen saturation entropy is associated with poor prognosis in critically ill patients with sepsis

Margaret Gheorghita  1 , Matthew Wikner  2 , Anika Cawthorn  3 , Tope Oyelade  1 , Kristof Nemeth  4 , Patrick Rockenschaub  5 , Ferran Gonzalez Hernandez  6 , Nel Swanepoel  3 , Watjana Lilaonitkul  5   7 , Ali R Mani  1
Affiliations

Reduced oxygen saturation entropy is associated with poor prognosis in critically ill patients with sepsis

Margaret Gheorghita et al. Physiol Rep. 2022 Dec.

Abstract

Recent studies have found that oxygen saturation (SpO2 ) variability analysis has potential for noninvasive assessment of the functional connectivity of cardiorespiratory control systems during hypoxia. Patients with sepsis have suboptimal tissue oxygenation and impaired organ system connectivity. Our objective with this report was to highlight the potential use for SpO2 variability analysis in predicting intensive care survival in patients with sepsis. MIMIC-III clinical data of 164 adults meeting Sepsis-3 criteria and with 30 min of SpO2 and respiratory rate data were analyzed. The complexity of SpO2 signals was measured through various entropy calculations such as sample entropy and multiscale entropy analysis. The sequential organ failure assessment (SOFA) score was calculated to assess the severity of sepsis and multiorgan failure. While the standard deviation of SpO2 signals was comparable in the non-survivor and survivor groups, non-survivors had significantly lower SpO2 entropy than those who survived their ICU stay (0.107 ± 0.084 vs. 0.070 ± 0.083, p < 0.05). According to Cox regression analysis, higher SpO2 entropy was a predictor of survival in patients with sepsis. Multivariate analysis also showed that the prognostic value of SpO2 entropy was independent of other covariates such as age, SOFA score, mean SpO2 , and ventilation status. When SpO2 entropy was combined with mean SpO2 , the composite had a significantly higher performance in prediction of survival. Analysis of SpO2 entropy can predict patient outcome, and when combined with SpO2 mean, can provide improved prognostic information. The prognostic power is on par with the SOFA score. This analysis can easily be incorporated into current ICU practice and has potential for noninvasive assessment of critically ill patients.

Keywords: SpO2; entropy; oxygen saturation; sepsis; survival; variability.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Multiscale entropy of SpO2 across 5‐time scales. Error bars represent the standard error mean (SEM).
FIGURE 2
FIGURE 2
(a) ROC curve for classifying survival in critically ill patients with sepsis based on SpO2 mean (AUC = 0.498), SpO2 entropy (AUC = 0.654), and composite SpO2 mean and entropy (AUC = 0.705). (b) Survival analysis of patients above and below optimum composite cut off obtained from ROC curve.
FIGURE 3
FIGURE 3
ROC curves for classifying survival in training and validation samples. Composite SpO2 mean and entropy index for each patient in the validation sample was calculated based on Cox regression coefficients of the training sample. AUC of both samples are significantly different from a random classifier (AUC = 0.5), p = .036 and p = .016 for the training and validation samples, respectively.
See this image and copyright information in PMC

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