Determinants of resistive index shortly after transplantation: independent relationship with delayed graft function

Measurement of the vascular resistive index (RI) by Doppler ultrasonography has been proposed as a non-invasive method to evaluate renal allograft dysfunction, but there are conflicting reports about its clinical utility. The aim of our study was to analyse the donor and recipient characteristics related to RI measured at days 2 and 3 after renal transplantation and the relationship between RI and allograft outcome. RI was measured by Doppler ultrasonography in 333 patients at days 2 or 3 post-transplantation. Donor and recipient variables and allograft outcome were collected from a prospectively maintained institutional database. In patients with RI higher than 0.7, donor age, recipient age, duration of renal replacement therapy, incidence of diabetes, hypertension and atherosclerosis in the recipient, pulse pressure, initial creatinine and the incidence of delayed graft function (DGF) were higher. After multivariate analysis, the only variables that remained significant for an increased risk of higher RI were recipient age over 55 years, presence of diabetes in the recipient and DGF. Recipient age, previous diabetes mellitus and DGF are the most important determinants of transplant kidney RI in the first days after transplantation. So both the graft recipient and the graft itself, but not the donor, determine intra-renal Doppler indices.