To study the changes in the renal artery and renal vein with renal cortical and medullary microcirculatory blood flow in patients with sepsis; to study the relationship between renal arteriolar and renal vein with renal cortical and medullary microcirculatory blood flow and renal function; and to find the value of ultrasonographic assessment of renal blood flow indices for evaluating prognosis in patients with sepsis.

Inclusion Criteria:

• Age between 18-85 years old; Control group: patients with non-acute kidney injury after ICU general surgery; Observation group: patients who met the diagnostic criteria of AKI: Scr elevation ≥26.5 umol/L within 48h; Scr elevation exceeding 1.5 times and more than the basal value within 7d; and decrease in urine output (<0.5 ml/kg/h) with a duration of 6h or more.

Exclusion Criteria:

• Those who did not meet the inclusion criteria or refused to be enrolled; patients with underlying end-stage renal disease or requiring long-term dialysis; renal transplant patients; patients with other underlying systemic diseases causing renal dysfunction (SCr > 88.4 umol/L); those who were unable to obtain a clear renal ultrasound view; those with suspected contrast allergy; those with pulmonary arterial systolic blood pressure ≥ 90 mm Hg; and those who were pregnant or breastfeeding women.

Age between 18-85 years old; Control group: patients with non-acute kidney injury after ICU general surgery; Observation group: patients who met the diagnostic criteria of AKI: Scr elevation ≥26.5 umol/L within 48h; Scr elevation exceeding 1.5 times and more than the basal value within 7d; and decrease in urine output (<0.5 ml/kg/h) with a duration of 6h or more.