title: Intrarenal vascular resistance parameters in kidney transplant patients receiving calcineurin inhibitor-based or sirolimus-based regimens.
abstract: BACKGROUND
  Use of a calcineurin inhibitor (CNI) immunosuppressant following kidney transplantation is associated with development of vasomotor nephrotoxicity. This study was undertaken to evaluate and compare the influences of CNI-based and CNI-free immunosuppressant regimens on two intrarenal vascular resistance parameters, the resistive index (RI) and the pulsatility index (PI), in renal transplant recipients.
  
  
  METHODS
  Forty-nine renal transplant patients who received ultrasonography examination between January 2007 and December 2007 were enrolled in this case-control study. Thirty-one subjects received a CNI-based regimen, and 18 received a CNI-free (sirolimus-based) regimen. RI and PI were determined by duplex Doppler ultrasonography.
  
  
  RESULTS
  Patients receiving a CNI displayed lower cholesterol and triglyceride values and higher RI (mean: 0.7 vs. 0.6, P = 0.002) and PI values (mean: 1.3 vs. 1.1, P = 0.034). Multivariate analyses revealed that advanced age and use of alpha-blockers or diuretics were modestly associated with higher RI and PI values. By multivariate analysis, use of sirolimus was associated with a lower RI by -0.05 [95% confidence interval (CI): -0.085, -0.019; P = 0.003] but not with a lower PI (95% CI: -0.245, 0.001; P = 0.053).
  
  
  CONCLUSIONS
  Use of sirolimus is only modestly correlated with a reduced RI and is not associated with a reduced PI. These observations question the superiority of CNI-free over CNI-based regimens with regard to reduction of intrarenal vascular resistance post-transplantation. These findings combined with those regarding recipient factors also cast doubt on the specificity of intrarenal resistance indices for predicting allograft function and/or survival.
authors.affiliation: Department of General Surgery, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin County, Taiwan.
authors.forename: Po-Chu
authors.initials: PC
authors.lastname: Lee
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Lee
authors.forename: Rey-Heng
authors.initials: RH
authors.lastname: Hu
authors.forename: Chiao
authors.initials: C
authors.lastname: Lo
authors.forename: Meng-Kun
authors.initials: MK
authors.lastname: Tsai
authors.forename: Po-Huang
authors.initials: PH
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D065095:Calcineurin Inhibitors; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007668:Kidney / Q000503:physiopathology; D016030:Kidney Transplantation; D008297:Male; D015999:Multivariate Analysis; D020123:Sirolimus / Q000494:pharmacology*; D018615:Ultrasonography, Doppler, Color; D014655:Vascular Resistance / Q000187:drug effects*
chemical_list: D065095:Calcineurin Inhibitors; D007166:Immunosuppressive Agents; D020123:Sirolimus