Preoperative cerebral oxygenation in high-risk noncardiac surgical patients: an observational study on postoperative mortality and complications

Fig. 1. Histograms of rScO2 values in a seated position a under ambient air and b under administration of 2 L per minute of oxygen. Histogram showing the distribution of rScO2 values and binned frequency counts

Fig. 2. Receiver operating curve analysis of preoperative cerebral oxygen saturation rScO2 and the combined endpoint of all evaluated complications. Blue ROC curve breathing ambient air (p = 0.05) and red ROC curve breathing 2 L per minute oxygen (p = 0.047)

Fig. 3. Boxplots of rScO2 distribution comparing a breathing ambient air or b breathing 2 L per minute oxygen regarding increasing NYHA Class. The box represents 25th and 75th percentiles; the range between them is the interquartile range. Within the box, the bold line represents the median. The whiskers (extensions from the box) indicate the lowest and highest value no further than 1.5 times the interquartile range. Outliers (values beyond whiskers) are shown as dots

Fig. 4. Boxplots of rScO2 distribution comparing a breathing ambient air or b breathing 2 L per minute oxygen regarding LVEF Class [31]. Left ventricular function Class (1) Normal = LVEF 50–70% (midpoint 60%), (2) Mild dysfunction = LVEF 40–49% (midpoint 45%), (3) Moderate dysfunction = LVEF 30–39% (midpoint 35%), (4) Severe dysfunction = LVEF less than 30%. The box represents 25th and 75th percentiles; the range between them is the interquartile range. Within the box, the bold line represents the median. The whiskers (extensions from the box) indicate the lowest and highest value no further than 1.5 times the interquartile range. Outliers (values beyond whiskers) are shown as dots

Fig. 5. Boxplots of rScO2 distribution comparing a breathing ambient air or b breathing 2 L per minute oxygen regarding body position. On the left side of the diagram the boxplot represents the rScO2 distribution of the patient in the seated position, subsequently the measurement was repeated in the supine position, shown on the right side of the diagram. The box represents 25th and 75th percentiles; the range between them is the interquartile range. Within the box, the bold line represents the median. The whiskers (extensions from the box) indicate the lowest and highest value no further than 1.5 times the interquartile range

Fig. 6. Correlation of rScO2 to preoperative hemoglobin value in a seated position and room air b in seated position under oxygen supplementation. R² Pearson correlations coefficient, p level of significance