Objective:To explore the value of flow-mediated vasodilation(FMD)of brachial artery,which was assessed by high-frequency ultrasound assessment,combined with serum phosphatidylserine 1 phosphate(S1P)levels in predicting vascular endothelial function of patients with sepsis.Methods:A total of 140 patients with sepsis who admitted to the People's Hospital of Nanchuan Chongqing from February 2021 to February 2023 were selected as the case group,and 140 volunteers who underwent health physical examinations in the hospital during the same period were selected as the healthy control group.High-frequency ultrasound was used to measure the brachial artery FMD of the two groups,and the serum S1P levels of the two groups were also detected.The correlation between FMD,S1P and vascular endothelial function in patients with sepsis was analyzed,as well as the diagnostic performances of FMD and S1P in assessing vascular endothelial function of patients with sepsis.And then,the correlation between FMD,S1P levels and the vascular endothelial function score(VEFS)in patients with sepsis was further analyzed.Results:The FMD(4.21±1.63),S1P(0.82±0.24)and VEFS(0.42±0.15)levels in the case group were significantly lower than those(7.35±2.15,1.28±0.32,0.78±0.18)in the healthy control group(t=-14.23,-13.56,-17.32,P<0.05),respectively.The FMD and S1P levels were significantly positive correlation with VEFS in the case group(r=0.62,0.58,P<0.01),and they were significantly negative correlation with C-reactive protein(CRP)(r=-0.55,-0.51,P<0.01),respectively.As single-factor indicators of predicting vascular endothelial function of patients with sepsis,area under curve(AUC)values of receiver operating characteristic(ROC)curves of FMD and S1P levels were respectively 0.83 and 0.82,and the sensitivities of them were respectively 74.0%and 77.0%,specificities of them were respectively 78.0%and 75.0%.As the multi-factor indicator of predicting vascular endothelial function of patients with sepsis,the AUC,sensitivity and specificity of the combination of FMD and S1P levels were respectively 0.90,88.0%and 77.0%.Conclusion:Brachial artery FMD,which is assessed by high-frequency ultrasound,combined with serum S1P levels can effectively predict vascular endothelial function of patients with sepsis,which has important clinical significance in diagnosing and treating patients with sepsis.