Background:Evaluating the hemodynamic status and predicting fluid responsiveness are important in critical ultrasound assessment of shock patients.Transthoracic echocardiography with noninvasive diagnostic parameters allows the assessment of volume responsiveness.This study aimed to assess the hemodynamic changes in the liver and systemic hemodynamic changes during fluid challenge and during passive leg raising (PLR) by measuring hepatic venous flow (HVF) velocity.Methods:This is an open-label study in a tertiary teaching hospital.Shock patients with hypoperfusion who required fluid challenge were selected for the study.Patients ＜18 years old and those with contraindications to PLR were excluded from the study.Baseline values were measured,PLR tests were performed,and 500 ml of saline was infused over 30 min.Parameters associated with cardiac output (CO) in the left ventricular outflow tract were measured using the Doppler method.In addition,HVF velocity and right ventricular function parameters were determined.Results:Middle hepatic venous (MHV) S-wave velocity was positively correlated in all patients with CO at baseline (r=0.706,P ＜ 0.01) and after volume expansion (r =0.524,P =0.003).CO was also significantly correlated with MHV S-wave velocity in responders (r =0.608,P ＜ 0.01).During PLR,however,hepatic venous S-wave velocity did not correlate with CO.For the parameter ΔMHV D (increase in change in MHV D-wave velocity after volume expansion),defined as (MHV DafterVE-MHV DBaseline)/MHV DBaseline × 100％,＞21％ indicated no fluid responsiveness,with a sensitivity of 100％,a specificity of 71.2％,and an area under the receiver operating characteristic curve of 0.918.Conclusions:During fluid expansion,hepatic venous S-wave velocity can be used to monitor CO,whether or not it is increasing.AMHV D ≥21％ indicated a lack of fluid responsiveness,thus helping to decide when to stop infusions.