Clinical application of Doppler ultrasound with contrast-enhanced ultrasound in septic acute kidney injury: from macroscopic to microscopic renal perfusion perspectives / 中华超声影像学杂志

ABSTRACT

Objective:To analyse the changes in color Doppler and contrast-enhanced ultrasound (CEUS) blood flow parameters in patients with septic acute kidney injury (AKI) from the perspective of macroscopic circulation and microscopic circulation perfusion, in order to explore the value of clinical application of ultrasound in this disease.Methods:A total of 53 ICU-admitted patients diagnosed with septic AKI at the Second Affiliated Hospital of Soochow University from January 2021 to May 2022 were selected.Patients with septic AKI were classified into stages 1-3 according to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) AKI diagnostic criteria, with stage 1 being the mild group(17 cases), stages 2 and 3 being the severe group(21 cases), and septic patients without AKI in the same period being the control group(15 cases). The ultrasound parameters such as the relative blood flow(RBF) and time-averaged velocity(TAV) of the renal artery as well as the cardiac output (CO) and cardiac index (CI) in the macroscopic circulation were measured, and the time-intensity curve was analysed by the CEUS analysis software to calculate the microscopic parameters such as time to peak(TTP), rise time(RT), fall half time(FHT) and mean transit time(MTT), and the cardiac output and cardiac index were also measured. The differences in ultrasound Doppler and CEUS parameters among the various groups were compared. The diagnostic effectiveness of each parameter for severe AKI was assessed using ROC curve analysis.Results:①In macrocirculation, the renal blood flow (RBF) and time-averaged velocity (TAV) gradually decreased ( P=0.004, P<0.001) as the disease progressed in AKI patients. But the difference of CO and CI among the three groups were not statistically significant in each group ( P=0.17, 0.12). ②In microcirculation, the renal interlobar artery Doppler parameters pulsatility index (PI), resistance index (RI), and systolic/diastolic flow ratio (S/D) gradually increase in patients with septic AKI ( P<0.05) and the CEUS parameters TTP, RT, FHT and MTT were prolonged ( P<0.001, P=0.003, P=0.004, P=0.009). ③The combined diagnosis of RI and TTP was more beneficial in diagnosing septic AKI in critically ill patients [AUC=0.93(0.85-1.00)]. Conclusions:Color Doppler ultrasound combined with CEUS can detect reduced macroscopic and microscopic circulation in patients with septic AKI, especially in those with severe AKI, and this is independent of changes in CO or CI.