Renal resistive index measurements by ultrasound in patients with liver cirrhosis:Magnitude and associations with renal dysfunction

BACKGROUND The hemodynamic alterations seen in liver cirrhosis lead to renal vasoconstriction,ultimately causing acute kidney injury(AKI).The renal resistive index(RRI)is the most common Doppler ultrasound variable for measuring intrarenal vascular resistance.AIM To evaluate the association of the RRI with AKI in patients with liver cirrhosis and to identify risk factors for high RRI.METHODS This was a prospective observational study,where RRI was measured using Doppler ultrasound in 200 consecutive hospitalized patients with cirrhosis.The association of RRI with AKI was studied.The receiver operating characteristic(ROC)curve analysis was utilized to determine discriminatory cut-offs of RRI for various AKI phenotypes.Multivariate analysis was conducted to determine the predictors of high RRI.RESULTS The mean patient age was 49.08±11.68 years,with the majority(79.5%)being male;the predominant etiology of cirrhosis was alcohol(39%).The mean RRI for the study cohort was 0.68±0.09,showing a progressive increase with higher Child-Pugh class of cirrhosis.Overall,AKI was present in 129(64.5%)patients.The mean RRI was significantly higher in patients with AKI compared to those without it(0.72±0.06 vs 0.60±0.08;P<0.001).A total of 82 patients(41%)had hepatorenal syndrome(HRS)-AKI,29(22.4%)had prerenal AKI(PRA),and 18(13.9%)had acute tubular necrosis(ATN)-AKI.The mean RRI was significantly higher in the ATN-AKI(0.80±0.02)and HRS-AKI(0.73±0.03)groups than in the PRA(0.63±0.07)and non-AKI(0.60±0.07)groups.RRI demonstrated excellent discriminatory ability in distinguishing ATN-AKI from non-ATN-AKI(area under ROC curve:93.9%).AKI emerged as an independent predictor of high RRI(adjusted odds ratio[OR]:11.52),and high RRI independently predicted mortality among AKI patients(adjusted OR:3.18).CONCLUSION In cirrhosis patients,RRI exhibited a significant association with AKI,effectively differentiated between AKI phenotypes,and predicted AKI mortality.

Role of imaging in the evaluation of renal dysfunction in heart failure patients

Heart failure and kidney disease share common pathophysiological pathways which can lead to mutual dysfunction,known as cardiorenal syndrome.In heart failure patients,renal impairment is related to hemodynamic and nonhemodynamic factors.Both decreased renal blood flow and renal venous congestion due to heart failure could lead to impaired renal function.Kidney disease and worsening renal function are independently associated with poor prognosis in heart failure patients,both in acute and chronic clinical settings.The aim of this review is to assess the role of renal imaging modalities in the evaluation and management of heart failure patients.Renal imaging techniques could complete laboratory data,as estimated glomerular filtration rate,exploring different pathophysiological factors involved in kidney disease and adding valuable information about renal structure and function.In particular,Doppler examination of arterial and venous hemodynamics is a feasible and non invasive technique,which has proven to be a reliable method for prognostic stratification in patients with cardiorenal syndrome.The renal resistance index,a measure related to renal hemodynamics,can be calculated from the Doppler evaluation of arterial flow.Moreover,the analysis of Doppler venous flow patterns can integrate information from the arterial study and evaluate renal congestion.Other imaging modalities are promising,but still confined to research purposes.

Study and observation of ultrasound on hemorheology of continuous renal replacement therapy in ICU

Objective: To observe the influence of bedside ultrasound on Hemodynamics of Continuous Renal Replacement Therapy,and explore the clinical value of bedside ultrasound technique in acute kidney injury (AKI) Patients with continuous renal replacement therapy (CRRT) and capacity management. Methods 311 cases of AKI patients with CRRT were divided randomly into Observe group and Control group. the observe group was used bedside ultrasound technique, by monitoring tricuspid annular plane systolic excursion (TAPSE), internal diameter of inferior vena cava (IVC), respiratory variation index of the inferior vena cava internal diameter (RVI) and left vertical Tei index changes. Meanwhile, each parameter change was mediated by ultrasound detection from before, to 30min, 6h, 12h, 36h, 48h after of CRRT to sustain liquid balance in observe group, however, central venous pressure (CVP) change was modulated in control group. The difference of kidney length in pre-CRRT were examined to exclude, and of renal aortic diameter, renal resistance index (RRI)and renal blood flow in post-48h of CRRT were compared in two groups. Results Renal length, Renal parenchyma thickness and Echo strength of renal parenchyma weren't different statistically in pre-CRRT of two groups(P>0.05). In observe group, the RVI level was started to increase significantly and IVC internal diameter to decrease at 6h, which would tend to stable at 36h(F=27.746 and 15.446 respectively);the TAPSE level was gradual ascending and Tei index was descending at 12h with a stable tendency at 24h of CRRT(F=36.213 and 17.127 respectively), and there was difference statistical among time of obvious change in TAPSE, IVC internal diameter, RVI and Tei index(P<0.05);In control group, there was no difference statistical among each time in CVP(F=2.189, P>0.05). Compared with control group, renal aortic diameter and renal blood flow were increased significantly(t=2.356 and 2.075), RRI was decreased obviously in observe group(t=2.244), which was different in statistics (P<0.05). Conclusion the application of bedside ultrasound technique in AKI patient's capacity management with CRRT was more effective and evaluated the kidney perfusion.

Relationship between Serum Uric Acid Levels and Kidney Arteriole Resistance in Patients with Type 2 Diabetes Associated with Hypertension

Objectives To investigate the relationship between serum uric acid levels and arteriole resistance detected with the color Doppler energy imaging (CDEI) and to explore the risks of impaired regulation of vascular tone by uric acid in kidneys of hypertension patients. Methods In 12 healthy control cases, 28 non-diabetic hypertension (nNIDDM +H) cases and 25 type 2 diabetic hypertension (NIDDM+H) cases, uric acid (UA) levels were measured with uricase-peroxidase method. Arteriole resistance index (RI) and pulsate index (PI) in separate sections of renal artery included MAR, SRA, IRA were detected using CDEI with 2.1~4.2 Hz Doppler transducer in kidneys. Results In comparison, UA was significantly higher in non-diabetic hyper- tension group and diabetic hypertension group than in control group (P<0.01, separately). UA levels was also significantly higher in NIDDM+H group than in nNIDDM+H, P < 0.029. RI in separate sections of renal artery was significantly higher in nNIDDM+H, or NIDDM+H group than in control group ( all P < 0.01) , and it was significantly higher in NIDDM +H than nNIDDM+H groups (P < 0.05 and P < 0.01). In nNIDDM +H and NIDDM +H groups UA levels and IRA-RI could be elevated significantly following with the impaired heart function being aggravated (χ2 = 13.028, P=0.005, χ2=13.29, P=0.004); the dosage of HCT being increased (χ2 =14.216, P=0.001, χ2 = 14.661, P=0.001); the levels of GHbA1 being excessed unnormally (P=0.000). The correlation between UA and IRA-RI in both hypertension groups were directly related, in nNIDDM+H group r=0.842, P=0.000, in NIDDM+H group, r=0.797, P=0.000. Conclusions Uric acid levels and IRA-RI in hyper-tension patients were directly related. Uric acid levels and IRA-RI could be partly dependent on the severity of heart dysfunction, diuretic dose, and serum glucose status of diabete patients in long-term. Uric acid and the xanthine oxidase metabolic pathway may contribute to impaired regulation of arteriole tone in hypertension patients.

Altered nuclear factor-kappaB inducing kinase expression in insulin-resistant mice

Background Insulin resistance is an underlying feature of both type 2 diabetes and metabolic syndrome. Currently, it is unclear whether nuclear factor （NF）-KB inducing kinase （NIK） plays a role in the development of insulin resistance. The present in vivo study investigated the roles of NIK and IKB kinase a （IKKa） in obesity-induced insulin resistance using animal models. Methods NIK expression was evaluated by Western blotting in male Lepob mice and C57BL/6J mice fed a high-fat diet （HFD） （45% fat）. After metformin and sulfasalazine treatment, NIK expression was investigated during the improvement of insulin resistance. Results NIK was increased by about 1-fold in the renal tissues of Lepab mice and C57BL/6J mice fed a HFD for 12 weeks. After 1 and 3 weeks of high-fat feeding, we observed an almost 50% decrease in NIK and IKKa expression in the liver and renal tissues of C57BL/6J mice. NIK expression was significantly lower in the liver and renal tissues of HFD-fed mice that were treated with insulin sensitizers, metformin and sulfasalazine. However, IKKa expression was increased after metformin treatment in both tissues. Conclusion These results suggest a possible role of NIK in the liver and renal tissues of insulin-resistant mice.