Plasma levels of the three endothelial-specific proteins von Willebrand factor, tissue factor pathway inhibitor, and thrombomodulin do not predict the development of acute respiratory distress syndrome.

Abstract

To determine if the plasma levels of three endothelial-specific proteins, von Willebrand factor (vWF), tissue factor pathway inhibitor (TFPI) and thrombomodulin (TM) may be useful in predicting the development of acute respiratory distress syndrome (ARDS). Blood samples were obtained from normal healthy volunteers and on the first day from patients at risk for ARDS and those with ARDS. Daily sequential measurements of vWF and TFPI were performed in two patients. Normal subjects were employees at Saint Louis University Hospital, St. Louis, Missouri. Patients at risk and those with ARDS were patients admitted to the medical and surgical floors and the intensive care units at St. Louis University Hospital. Plasma levels of vWF, TFPI and TM were measured in 27 normals, and on day 1 in 15 patients at risk for ARDS and 18 patients with ARDS from different etiologic factors. Plasma levels of vWF were significantly elevated in the at-risk (p < 0.01) and ARDS group (p < 0.001) as compared to normals but did not differ significantly between the two groups (p > 0.05). Plasma levels of TFPI were not significantly different between the normal and the at-risk group (p > 0.05); however, they were significantly elevated in ARDS as compared with at-risk and normal groups (p < 0.001). Levels of TM were significantly increased in the at-risk group as compared to normals (p < 0.01) but were not significantly different from the ARDS group (p > 0.05). Eight patients at risk progressed to develop ARDS. A vWF level of > 300% in patients at risk was 62% sensitive and 71% specific for predicting the development of ARDS with a positive predictive value of only 34%. TFPI levels were normal in 7 of the 8 patients who developed ARDS. A TM level of > 100 ng/ml in patients at risk was 50% sensitive and 57% specific with a positive predictive value of merely 8% for development of ARDS. There was no significant difference in the mean plasma levels of the three proteins on day 1 in patients at risk who developed ARDS as compared with those who did not develop ARDS. There was also no difference in mean plasma levels of the three proteins in patients with ARDS from sepsis as compared with ARDS from other etiologies. Plasma levels of vWF and TFPI correlated significantly. Plasma levels of vWF, TFPI and TM did not appear to serve as useful markers for predicting ARDS in patients at risk.