Comparative Ultrasound Evaluation of Renal Resistive Index in Hypertensive and Normotensive Adults in Ibadan, SouthWestern, Nigeria

Abstract

Background: Renal resistive index is a useful measure for quantifying alterations in renal blood flow. It is considered to be a reflection of renal parenchymal vascular resistance. The aim of this study is to determine the difference in renal resistive index between patients with essential hypertension and nonhypertensive control group.
Patients and Methods: Seventy -two patients with essential hypertension of varying duration and 68 patients without hypertension were evaluated sonographically in this prospective study. The renal resistive index was determined by use of Doppler ultrasound of the interlobar arteries.
Results: Mean renal resistive index in the hypertensive patients was 0.60 ± 0.04 (± SD) and in the controls was 0.56 ± 0.04 (± SD) (p= <0.001). Renal resistive index correlated significantly with systolic blood pressure (r=0.382, p= <0.001) and diastolic blood pressure (r= 0.364, p=<0.001). It correlated weakly with body mass index (r= 0.170, 0.044). No significant association was found with age, gender, duration of hypertension and creatinine clearance. Multiple regression linear analysis showed systolic blood pressure to be the only independent variable influencing renal resistive index.
Conclusion: The renal resistive index is increased in essential hypertension and correlates with patient’s blood pressure and body mass index. Doppler
ultrasound provides a non-invasive parameter for follow up of patients with essential hypertension especially in developing countries.