Fig. 3

a S1P levels were associated with the number of non-pulmonary organ failures (P = 0.001). b APACHE II scores were highly negatively correlated with baseline serum S1P levels in ARDS patients. c APACHE II scores showed a weaker negative correlation with day 7 S1P levels in ARDS patients. ARDS acute respiratory distress syndrome, S1P sphingosine-1-phosphate, APACHE II acute physiology and chronic health evaluation II