RELEVANCE OF RESISTIVE INDEX ULTRASONOGRAPHIC MEASUREMENT IN RENAL-TRANSPLANTATION

The usefulness of the ultrasonographic measurement of resistive index (RI) is not yet fully understood. To obtain a better definition of its relevance in renal disease we studied this parameter in a group of 21 2 renal transplant patients, aged between 15 and 55 years: 81 first gr afts with an excellent renal function, 44 hypertensive patients, 30 ty pe II diabetics, 29 cases of chronic graft dysfunction, 28 cases durin g an episode of acute rejection. RI was measured in three different re nal vascular areas: prerenal, interlobar and cortical. A two-way analy sis of variance showed a statistical significance for the site of RI s ampling and the type of pathology. There was no interaction between th e two variables studied (p = 0.30). Plasma creatinine levels, analyzed as covariate, showed a high statistical correlation with RI values (p = 0.0001). The mean RI of the XO transplanted patients with normal cr eatinine plasma levels showed a remarkable homogeneity and a statistic ally significant progressive reduction of the values from the main ren al artery to the interlobar and cortical vessels (p = 0.00001). In the other groups a greater dispersion of data was present. RI values sign ificantly increased in hypertensive and diabetic patients (p = 0.05) b ut more in acute rejection (p = 0.0001) or chronic graft dysfunction ( p = 0.01). In acute rejection and in chronic graft dysfunction the cur ve of RI values tended to become flat, while in hypertensive and diabe tic patients the aspect of the curve became steeper. In conclusion, RI is a hemodynamic index that reflects the vascular status of the explo red area and is not only the simple expression of reduction of the kid ney functional units. The differences observed in the various kidney a reas stress the importance of measuring this parameter at more than on e vascular site. The increase in RI values on the kidney cortex vessel s is likely to be an index of glomerular hyperfiltration. If this hypo thesis is true the measure of RI might be a reliable method for diagno sing in the kidney vascular damage, glomerular hypertension and hypert rophy.