Doppler-based evaluation of intrarenal venous flow as a new tool to predict acute kidney injury: A systematic review and meta-analysis

Congestion is a common complication in the critical care setting, these patients are at increased risk of developing acute kidney injury (AKI). Congestive nephropathy (CN) has recently been described as a mechanism of worsening renal function, and evaluation of renal venous flow by pulsed Doppler (PD) is a useful tool to assess the presence of renal vein congestion. We comprehensively explore the ability of the PD in the evaluation of the intrarenal venous flow (IRVF) to predict the development of AKI in critically ill patients. We searched Pubmed-MEDLINE, Scopus, Embase, and Cochrane Library of Systematic Reviews (to 31th December 2021). We evaluated the association between Doppler-based Intrarenal venous flow demodulation and AKI. CN was defined as the presence of a pulsatile pattern (biphasic or monophasic) in the PD. A total of 4 articles (660 patients) were included in our systematic review, three of these in the metanalysis (413 patients): one study was excluded because its data were inadequate for pooling. Two studies originated in Europe and the other two in the United States. AKI occurrence ranged between 34 and 68%. Patients who developed AKI had a significant difference in PD pattern (continuous vs. pulsatile) in the IRVF (RR=0.46; 95% CI 0.28-0.76). Nevertheless, a large heterogeneity was observed among the studies (I2=68.7%; p=0.04). Albeit preliminary, these findings suggest that the presence of a pulsatile pattern in the PD of the IRVF may be involved in the development of AKI in the critically ill patient. The effect of alterations in the IRVF and renal function warrant further investigation.

[Diagnostic efficiency of renal ultrasound after the first urine infection in infants]

INTRODUCTION

Several authors question the performance of systematic renal ultrasound after first urinary tract infection (UTI) in young children, given the high sensitivity of prenatal ultrasounds to detect major malformations and the low prevalence of clinical relevant findings. The aims of this study are to evaluate the yield of renal ultrasound performed after the first UTI in patients aged less than 2 years and to analyse potential risk factors (RF) of altered renal ultrasound.

PATIENTS AND METHODS

Retrospective study, including patients aged less than 2 years diagnosed with UTI in the Emergency Department between July 2013 and December 2014. Patients with an underlying nephro-urological pathology, previous UTIs and those without prenatal or post-infection renal ultrasound were excluded. Altered renal ultrasound was defined as the presence of dilated urinary tract or structural abnormalities. Potential RF analysed were: male, age less than 3 months, presence of fever and microorganism other than Escherichia coli. Univariate and multivariate logistic regression were performed.

RESULTS

A total of 306 patients were included. Altered renal ultrasound was found in 35 cases (11.4%; 95% CI 8.3-15.5): 24 (68.6%) urinary tract dilation, and 11 (31%) structural abnormalities. Among the cases with altered ultrasound, 68.6% were male, 51.4% were younger than 3 months, 74.3% were febrile, and 31.4% were caused by microorganisms other than E. coli, compared to 45% (P=.009), 31.7% (P=.021), 78.2% (P=.597) and 10% (P=.001) of cases with normal ultrasound. In the multivariate analysis, age less than 3 months (OR 2.1; 95% CI 1.0-4.3, P=.05) and microorganism other than E. coli (OR 3.8; 95% CI 1.7-8.7, P=.002) remained as RF.

CONCLUSIONS

The yield of renal ultrasound after the first UTI is low. Its indication should be individualised according to the presence of RF: age less than 3 months and microorganism other than E. coli.