Should renal color Doppler ultrasonography be a routine test in newly diagnosed hypertensive patient?

Sonographic evaluation of hypertension: Role of atrophic index and renal resistive index

Hypertension can cause structural and functional renal damage. Intrarenal ultrasound parameters have been extensively investigated in hypertensive patients and among the parameters introduced, the renal resistive index (RI) is associated with the progression of chronic kidney disease and hypertension. Atrophic index (AI) is an indirect anatomical ultrasound index that reports the atrophic changes of the renal parenchyma and it is mainly studied in chronic glomerular diseases. The present study aimed to evaluate renal RI and AI in hypertensive patients with normal renal function. AI showed correlations with all parameters associated with renal function reduction (age, creatinine, and intrarenal arterial stiffness). AI, in combination with RI, can represent in hypertensive patients an additional marker for renal damage progression.

Renal Doppler Ultrasound in the Evaluation of Renal Function in Patients with Sepsis

This study was aimed to explore the renal Doppler ultrasound in the evaluation of renal function in patients with sepsis. Fifty patients with sepsis or septic shock were classified into the acute kidney injury (AKI) group (n =25) and the non-AKI group (n =25) according to whether they had AKI. The measurements of renal resistance index (RRI) and power Doppler ultrasound (PDU) were performed on all patients within 7 days of admission to the intensive care unit (ICU). The patient's renal function was assessed. The results showed that the RRI of the two groups showed a slight upward trend over time, and the RRI of the AKI group was higher than that of the non-AKI group. After 7 days in AKI group, the areas under the receiver operating characteristic (ROC) curves of RRI were 0.745, 0.683, 0.729, 0.856, 0.793, 0.819, and 0.836 (P <0.05). There were no statistically considerable differences in areas under ROC curves between the two groups (P >0.05). The grouping of AKI and the time were both fixed effects, and the individual patients were randomized effects. Besides, the linear models were statistically analyzed. The results showed that the differences between the two groups were statistically insignificant (P >0.05). There was no significant difference in the PDU scores measured at different times within 7 days after ICU admission between the two groups (P >0.05). In conclusion, renal Doppler ultrasound had a good adoption effect in the evaluation of the renal function of patients with severe sepsis, which is worth promoting in clinical practice.

Renal Functional Reserve Is Related to the Nondipping Phenotype and to the Exercise Heart Rate Response in Patients with Essential Hypertension and Preserved Renal Function

BACKGROUND

Renal functional reserve (RFR), defined as the difference between stress and resting glomerular filtration rate (GFR), may constitute a diagnostic tool to identify patients at higher risk of developing acute kidney injury or chronic kidney disease. Blunted RFR has been demonstrated in early stages of hypertension and has been attributed to impaired vascular reactivity due to an overactive sympathetic nervous system (SNS).

OBJECTIVE

The purpose of this study was to investigate whether RFR correlates with other phenotypes expressing overactivity of the SNS in patients with essential hypertension and preserved renal function.

METHODS

Thirty-six patients with untreated essential hypertension and a GFR >60 mL/min/1.73 m2 were enrolled. The following parameters were measured: RFR, 24-h ambulatory blood pressure (BP) profile, a treadmill stress test, and an echocardiographic examination. Urine and venous samples were obtained at specific time points for the determination of clinical parameters, and both resting and stress GFR were calculated by using endogenous creatinine clearance for the measurement of RFR after an acute oral protein load (1 g/kg).

RESULTS

Twenty-one patients had a RFR <30 mL/min/1.73 m2 and 15 had a RFR above this cutoff. A nondipping pattern of 24-h BP was significantly more frequent in patients with low RFR (57.1 vs. 25.0%, p < 0.05 for systolic BP and 52.3 vs. 10.0%, p < 0.02 for diastolic BP). Moreover, patients with lower RFR values showed a blunted heart rate (HR) response to exercise during treadmill test (r = 0.439, p < 0.05). None of the echocardiographic parameters differed between the two groups of patients.

CONCLUSIONS

In hypertensive patients with preserved GFR, reduced RFR is related to nondipping BP phenotype as well as to attenuated exercise HR response. Overactivity of the SNS may be a common pathway. Since loss of RFR may represent a risk factor for acute or chronic kidney injury, hypertensive patients with blunted RFR might need a more careful renal follow-up.

Renal intraparenchymal resistive index: the ultrasonographic answer to many clinical questions

The use of renal resistive indices (RRIs) for the study of renal microcirculation has in the past been proposed for the identification of renal organ damage or even to specifically identify injury to some areas of the renal parenchyma. Nevertheless, according to the most recent evidences from literature this organ-based conception of RRIs has been proven to be partial and unable to explain the RRIs variations in clinical settings of sepsis or combined organ failure of primitively extrarenal origin or, more generally, the deep connection between RRIs and hemodynamic factors such as compliance and pulsatility of the large vessels. The aim of this review is to explain the physiopathological basis of RRIs determination and the most common interpretative errors in their analysis. Moreover, through a comprehensive vision of these Doppler indices, the traditional and emerging clinical application fields for RRIs are discussed.

Renal resistive index in hypertensive patients

Spectral Doppler ultrasonography provides the evaluation of renal resistive index (RRI), a noninvasive and reproducible measure to investigate arterial compliance and/or resistance. RRI seems to possess an important role in the evaluation of diverse cases of secondary hypertension. In essential hypertension, RRI is associated with subclinical markers of target organ damage and reflects renal disease progression beyond albuminuria and creatinine clearance. Also, RRI can estimate cardiovascular and renal risk. The evaluation of RRI may also help the therapeutic decisions. Given its simple assessment, RRI emerges as a simple method and a "multifunctional" tool that could help on the cardiovascular risk evaluation of the hypertensive patient.