Assessment of Vascular Endothelial Dysfunction in Septic Patients Using Brachial Flow-Mediated Dilation: A Systematic Review and Meta-Analysis

Background/Objective: Sepsis remains a major cause of morbidity and mortality worldwide, making early risk stratification and prognosis critical. Vascular endothelial dysfunction is a hallmark of sepsis pathogenesis, with evidence suggesting that endothelial injury may occur early, preceding organ failure. Brachial flow-mediated dilation (FMD), a validated noninvasive ultrasound technique measuring endothelium-dependent vasodilation, serves as a surrogate marker of endothelial function, where lower FMD values reflect impaired function. This systematic review and meta-analysis aimed to evaluate the validity and quality of evidence on using FMD to measure vascular endothelial dysfunction in septic patients by comparing FMD (i) between septic patients and non-septic controls and (ii) between sepsis non-survivors and survivors. Methods: PubMed, Embase, Scopus, and Web of Science were searched until November 2024 for clinical studies assessing FMD in septic patients. A random-effects model was used for the meta-analysis, and quality of studies was assessed using the Newcastle–Ottawa Scale. Results: Eight studies were included, and seven underwent quantitative synthesis (385 septic patients, 106 non-survivors and 217 survivors). Compared with non-septic controls, septic patients demonstrated significantly lower FMD (pooled standardized mean difference (SMD) = −2.1617; 95% CI −3.8349 to −0.4885; p = 0.0113; I2 = 98.2939%). Within the sepsis cohort, non-survivors showed significantly attenuated FMD compared to survivors (pooled SMD = −0.7003; 95% CI −1.1133 to −0.2873; p = 0.001; I2 = 60.5593%). Conclusions: FMD shows potential as a surrogate marker of endothelial dysfunction for sepsis risk assessment, as evident by lower FMD in septic patients, particularly non-survivors.