Significant Correlation between Brachial Pulse Pressure Index and Renal Resistive Index

The renal resistive index (RI) is calculated as (peak systolic velocity - minimum diastolic velocity)/peak systolic velocity, and has been significantly associated with renal function. Pulse pressure index (PPI) is derived from a formula similar to renal RI, i.e. (systolic blood pressure - diastolic blood pressure)/systolic blood pressure. The purpose of this study was to investigate whether brachial PPI had a significant correlation with renal RI and could be used in identifying patients with impaired renal function.

We consecutively enrolled 255 patients referred for echocardiographic examination. The renal RI was measured from Doppler ultrasonography and blood pressure was measured from an ABI-form device.

Patients with brachial PPI ≥ 0.428 (mean value of brachial PPI) had a lower estimated glomerular filtration rate (eGFR) than those with brachial PPI < 0.428 (p < 0.001). After the multivariate analysis was completed, brachial PPI had a significant correlation with renal RI (unstandardized coefficient β = 0.53, p < 0.001). The areas under the curve for brachial PPI and renal RI in prediction of eGFR < 45 mL/min/1.73 m(2) were 0.682 and 0.893 (both p < 0.001), respectively.

Brachial PPI was significantly correlated with renal RI. Patients with higher brachial PPI had a more reduced renal function. Hence, brachial PPI may be able to quickly reflect the intrarenal vascular hemodynamics, and may serve as an important tool for screening and follow-up for patients with abnormal renovascular resistance.

Chronic kidney disease; Pulse pressure index; Resistive index.