Ultrasonographic assessment of renal microcirculation is a new vision for the treatment of intensive care unit associated acute kidney injury
Rongping Chen, Beijun Gao, Xinchen Wang, Hua Zhao, Xiaoting Wang, Dawei Liu, Xiaoting Wang, Dawei Liu
Abstract
Acute kidney injury (AKI) refers to a clinical syndrome that occurs as a result of a rapid decline in renal function caused by a variety of etiological factors. AKI is a common complication in critically ill patients, increasing length of hospital stay, hospitalization costs, and morbidity and mortality. In the Intensive Care Unit (ICU), sepsis, cardiac critical illness, hypovolemia, abdominal hypertension, and urinary tract obstruction are among the critical care-related factors that can cause AKI. The pathophysiological mechanisms of AKI are not exactly the same for different critical care etiologies. Altered perfusion is considered an important pathogenesis of AKI, and whether optimization of microcirculation is achieved after optimization of microcirculatory hemodynamics is a blind spot for clinicians. In recent years, contrast-enhanced ultrasound (CEUS) is an emerging imaging technique in the field of critical illness using highly echogenic but inert microbubbles to delineate areas of microvessel perfusion within organs, which has been widely used in oncology and other fields, and for ICU patients, CEUS can quantitatively assess the alterations in renal microcirculatory blood flow. Ultrasound microbubble contrast agent can be injected via peripheral vein through the pulmonary circulation to finally reach the target organ or tissue, to achieve tissue echo enhancement, and the contrast agent can be observed in the tissue of the area of interest. Evaluation of renal microcirculation using ultrasonography allows early detection of people at high risk of AKI, early intervention to avoid the occurrence and development of AKI, and organized and individualized hemodynamic therapy. Therefore, this review discusses the epidemiology of critical illness-related AKI, pathophysiological mechanisms, ultrasonography agents and their techniques, renal ultrasonography procedures and their applications, including the operational steps, renal ultrasonography images at different periods, and the meaning of CEUS parameters. Finally, the current applications of ultrasonography in severe disease-related AKI, especially the evaluation of intrarenal regional blood flow, are summarized.