Association between intrarenal venous flow from Doppler ultrasonography and acute kidney injury in patients with sepsis in critical care: a prospective, exploratory observational study

Abstract

Background Intrarenal venous flow (IRVF) patterns assessed using Doppler renal ultrasonography are real-time bedside visualizations of renal vein hemodynamics. Although this technique has the potential to detect renal congestion during sepsis resuscitation, there have been few studies on this method. We aimed to examine the relationship between IRVF patterns, clinical parameters, and outcomes in critically ill adult patients with sepsis. We hypothesized that discontinuous IRVF was associated with elevated central venous pressure (CVP) and subsequent acute kidney injury (AKI) or death. Methods We conducted a prospective observational study in two tertiary-care hospitals, enrolling adult patients with sepsis who stayed in the intensive care unit for at least 24 h, had central venous catheters placed, and received invasive mechanical ventilation. Renal ultrasonography was performed at a single time point at the bedside after sepsis resuscitation, and IRVF patterns (discontinuous vs. continuous) were confirmed by a blinded assessor. The primary outcome was CVP obtained at the time of renal ultrasonography. We also repeatedly assessed a composite of Kidney Disease Improving Global Outcomes of Stage 3 AKI or death over the course of a week as a secondary outcome. The association of IRVF patterns with CVP was examined using Student's t-test (primary analysis) and that with composite outcomes was assessed using a generalized estimating equation analysis, to account for intra-individual correlations. A sample size of 32 was set in order to detect a 5-mmHg difference in CVP between IRVF patterns. Results Of the 38 patients who met the eligibility criteria, 22 (57.9%) showed discontinuous IRVF patterns that suggested blunted renal venous flow. IRVF patterns were not associated with CVP (discontinuous flow group: mean 9.24 cm H2O [standard deviation: 3.19], continuous flow group: 10.65 cm H2O [standard deviation: 2.53], p = 0.154). By contrast, the composite outcome incidence was significantly higher in the discontinuous IRVF pattern group (odds ratio: 9.67; 95% confidence interval: 2.13–44.03, p = 0.003). Conclusions IRVF patterns were not associated with CVP but were associated with subsequent AKI in critically ill adult patients with sepsis. IRVF may be useful for capturing renal congestion at the bedside that is related to clinical patient outcomes. Graphical abstract

Coexistence of a fluid responsive state and venous congestion signals in critically ill patients: a multicenter observational proof-of-concept study

“…Andrei et al found a prevalence of abnormal VExUS score of 22% in a cohort of general critically ill patients at ICU admission without any correlation with AKI or mortality [ 44 ]. In contrast, ultrasound patterns of hepato-splanchnic venous congestion correlated with worse clinical outcomes in acute coronary [ 45 ] and septic patients [ 46 ]. Even though we found a positive association between altered VExUS and CVP, a known signal of VC and risk factor for adverse outcomes [ 12 , 47 ], and in line with previous reports [ 43 ], future studies should help to determine the best sensitivity, specificity and prognostic values of VexUS components in other high-risk critically ill patients, such as those with septic shock, RV failure or ARDS [ 48 ].…”

Comment on: Association between intrarenal venous flow from Doppler ultrasonography and acute kidney injury in patients with sepsis in critical care: a prospective, exploratory observational study

“…With great interest we read the recent article by Fujii et al [ 1 ], which brings forth valuable insights in the domain of volume assessment in critically ill patients. The authors conclude that distinct intrarenal venous flow (IRVF) patterns are indicative of renal venous congestion and that they do not correlate with central venous pressure (CVP) but are associated with subsequent acute kidney injury (AKI) in critically ill patients with sepsis.…”

“…It illustrates that assessment of fluid status remains challenging and will likely never be based on a single parameter. Ultrasonography represents an attractive tool in assessing fluid status due to its non-invasiveness as well as rapid and near universal availability in the ICU setting [ 1 , 2 , 5 ]. However, this study (and our raised concerns) should remind readers that most studies on ultrasound-guided volume assessment in critically ill patients are relatively small, often exploratory, and susceptible to various sources of bias.…”