Diagnosis of functional kidney failure of cirrhosis with Doppler sonography: prognostic value of resistive index.

Time-velocity wave-form analysis of Doppler signals from small intrarenal arteries allows estimation of intrarenal arteriolar vascular resistance. Among the various indexes proposed, the resistive index is the most widely used for this estimation. To investigate whether the resistive index is useful in the diagnosis of functional kidney failure and prediction of survival in cirrhotic patients with ascites, we measured resistive index, kidney and liver function and plasma levels of renin, aldosterone and antidiuretic hormone in 10 healthy subjects, 12 patients with compensated cirrhosis and 32 patients with cirrhosis and ascites (17 with kidney failure). A total of 28 clinical and laboratory variables were analyzed for prognostic value. Resistive index was significantly increased in patients with kidney failure (0.74 +/- 0.01) compared with those in the other three groups (0.64 +/- 0.01, 0.64 +/- 0.02 and 0.67 +/- 0.01) and correlated significantly with glomerular filtration rate, arterial pressure, plasma renin activity and free water clearance in the cirrhotic patients. The sensitivity and specificity of the resistive index in detecting kidney failure in patients with ascites were 71% and 80%, respectively. Nine variables were correlated with survival in the univariate analysis, including resistive index, age, hepatomegaly, blood urea nitrogen, serum creatinine, plasma sodium concentration, glomerular filtration rate, plasma renin activity and plasma concentration of antidiuretic hormone. Multivariate analysis disclosed only three independent predictors of survival: plasma renin activity, plasma concentration of antidiuretic hormone and serum sodium concentration. In conclusion, resistive index is a sensitive method to assess intrarenal hemodynamics in patients with cirrhosis and ascites. It also has predictive value for survival in these patients.