Evaluation of Contrast-Enhanced Ultrasound in Diagnosis of Acute Kidney Injury of Patients in Intensive Care Unit

Prognostic value of contrast-enhanced ultrasound in dogs with acute renal injury treated with haemodialysis

BACKGROUND

It is clinically relevant to predict outcomes in dogs with acute kidney injury (AKI) treated with haemodialysis. The aim of this study was to evaluate the prognostic value of contrast-enhanced ultrasound (CEUS) and its role in discriminating between AKI and acute impairment associated with chronic kidney disease (AKI/CKD).

METHODS

Dogs diagnosed with AKI or AKI/CKD were prospectively enrolled in the study. For all dogs, CEUS was performed at admission (T0). In addition, in haemodialysis-treated dogs, it was performed after the first dialysis (T1) and 7 days (T7) and 30 days (T30) after admission.

RESULTS

A total of 41 dogs were enrolled, of which 30 were treated with haemodialysis and 11 received medical therapy. No significant difference was found between CEUS values at T0 in surviving and non-surviving patients after haemodialysis. A significant difference in cortical peak enhancement intensity (PI) values was found between T0, T1, T7 and T30, with the highest PI value at T0, a significant reduction at T1 and a progressive reduction in subsequent checks. There were no significant differences in CEUS parameters at T0 between patients with AKI and AKI/CKD.

LIMITATIONS

AKI aetiology was unknown in most cases, which limits the generalisability of the findings. Furthermore, the small sample size means that the statistical analysis is likely underpowered.

CONCLUSION

CEUS could be helpful in evaluating of the prognosis of dogs with AKI during haemodialysis.

New ultrasound techniques for acute kidney injury diagnostics

PURPOSE OF REVIEW

Acute kidney injury (AKI) is common in critical illness and associated with adverse outcomes. Imaging, specifically ultrasound, is increasingly finding a role in AKI diagnostics. This includes the assessment of arterial and venous blood flow, tissue perfusion and the condition of the renal parenchyma. This review provides an update on ultrasound techniques and their application to AKI in critical care.

RECENT FINDINGS

Advances have been made in arterial and venous Doppler, contrast enhanced ultrasound (CEUS) and shear wave elastography (SWE). Doppler and CEUS techniques offer benefit in terms of AKI diagnosis and in identifying patients at risk. In addition, through the demonstration of altered flow or impaired perfusion, these techniques provide information on the pathophysiology of AKI, offering potential for targeted intervention. Renal SWE, an emerging technique, assesses tissue stiffness potentially allowing exploration of the role of venous congestion in the pathogenesis of AKI.

SUMMARY

Ultrasound continues to demonstrate great promise in the diagnosis and management of AKI, offering a noninvasive means to diagnose perfusion deficits and assess response to treatments. Further research, with standardization of techniques, may allow multifaceted renal ultrasound assessment in the critically ill for more accurate diagnosis and tailored intervention in AKI.

Contrast-Enhanced Ultrasound (CEUS) and Ultra-Microangiography (UMA) in Critically Ill Children with Acute Kidney Injury

Acute kidney injury (AKI) is an acute condition of impaired kidney function with decreased glomerular filtration rate, which results in dysregulation in volume, electrolyte, and acid-base equilibrium. AKI can be a life-threatening condition and can also lead to chronic kidney disease. It is important to diagnose AKI early in the course of the disease or to predict its development, as this can influence therapeutic decisions, outcome, and, consequently, the prognosis. In clinical practice, an elevated serum creatinine concentration remains the most common laboratory indicator for diagnosing AKI. However, due to the delay in its rise, creatinine levels are often insensitive and inaccurate for early diagnosis. Novel biomarkers of kidney tubular injury and the renal angina index have shown promise in predicting AKI earlier and more accurately. Contrast-enhanced ultrasonography (CEUS) and ultra-microangiography (UMA) are radiological methods that can quantify renal microperfusion and may be able to predict the development of AKI. They have not yet been used for quantifying renal perfusion in children with risk factors for developing AKI. Further research is needed to compare these sonographic techniques with the renal angina index and emerging kidney injury biomarkers for predicting acute kidney injury (AKI) in both children and adults.

Renal medullary perfusion differs from that in renal cortex in patients with sepsis associated acute kidney injury and correlates with renal function prognosis: A prospective cohort study

BACKGROUND

Renal perfusion status remains poorly studied at the bedside during sepsis associated acute kidney injury (AKI). The aim of the study is to examine renal cortical and medullary perfusion using renal contrast enhanced ultrasound (CEUS) in septic patients.

METHODS

In this single-center, prospective longitudinal study, septic patients were enrolled. Renal ultrasonography was performed within 24 hours of ICU admission (D1), then repeated at D3, D5 and D7. Each measurement consisted of three destruction replenishment sequences that were recorded for delayed analysis with dedicated software (Vuebox). Renal cortex and medulla perfusion were quantified by measuring time to peak (TTP). Receiver operating characteristic (ROC) analysis was used to evaluate 28-day renal prognosis.

RESULTS

The study included 149 septic patients, including 70 non-AKI patients and 79 AKI patients. Both renal cortical and medullary TTP was longer in the AKI group than in the non-AKI group. The difference of TTP between renal cortex and medulla in AKI group was higher than that in the non-AKI group (p = 0.000). Medullary TTP on day 3 had the best performance in predicting the prognosis of 28-day renal function (AUC 0.673, 95% confidence interval 0.528-0.818, p = 0.024), and its cut-off value was 45 s with a sensitivity 52.2% and a specificity of 82.1%. Cortical TTP on day 3 also had the performance in predicting the prognosis of 28-day renal function (AUC 0.657, 95% confidence interval 0.514-0.800, p = 0.039), and its cut-off value was 33 s with a sensitivity 78.3% and a specificity of 55.0%.

CONCLUSION

Renal medullary perfusion alterations differ from those in cortex, with the medulla is worse. Simultaneous and dynamic assessment of cortical and medullary microcirculatory flow alterations necessary. TTP on day 3, especially medullary TTP, seems to be a relatively stable and useful indicator, which correlates with 28-day renal function prognosis in septic patients. Early correction of renal cortical and medullary perfusion alterations reduces the incidence of adverse renal events.