title: Renal perfusion index reflects cardiac systolic function in chronic cardio-renal syndrome.
abstract: BACKGROUND
  Cardiac dysfunction can modify renal perfusion, which is crucial to maintain sufficient kidney tissue oxygenation. Renal cortex perfusion assessed by dynamic ultrasound method is related both to renal function and cardiac hemodynamics. The aim of the study was to test the hypothesis that Renal Perfusion Index (RPI) can more closely reflect cardiac hemodynamics and differentiate etiology of chronic cardio-renal syndrome.
  
  
  METHODS
  Twenty-four patients with hypertension and chronic kidney disease (CKD) at 2-4 stage (12 with hypertensive nephropathy and 12 with CKD prior to hypertension) were enrolled in the study. Blood tests, 24-h ABPM, echocardiography, and ultrasonography with estimation of Total renal Cortical Perfusion intensity and Renal Perfusion Index (RPI) were performed.
  
  
  RESULTS
  In the group of all patients, RPI correlated with left ventricular stoke volume (LVSV), and cardiac index, but not with markers of renal function. In multiple stepwise regression analysis CKD-EPI(Cys-Cr) (b=-0.360), LVSV (b=0.924) and MAP (b=0.376) together independently influenced RPI (R2=0.74; p<0.0001). RPI<0.567 allowed for the identification of patients with chronic cardio-renal syndrome with sensitivity of 41.7% and specificity of 83.3%.
  
  
  CONCLUSIONS
  Renal perfusion index relates more strongly to cardiac output than to renal function, and could be helpful in recognizing chronic cardio-renal syndrome. Applicability of RPI in diagnosing early abnormalities in the cardio-renal axis requires further investigation.
authors.affiliation: Department of Internal Diseases, Nephrology and Dialysis, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Lubas
authors.affiliation: Department of Cardiology and Internal Medicine, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Ryczek
authors.affiliation: Department of Internal Diseases, Nephrology and Dialysis, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Kade
authors.affiliation: Department of Internal Diseases, Nephrology and Dialysis, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Niemczyk
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use; D059347:Cardio-Renal Syndrome / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000652:urine; D002908:Chronic Disease; D005260:Female; D006334:Heart Function Tests; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D012372:ROC Curve; D013318:Stroke Volume; D013599:Systole; D014463:Ultrasonography
chemical_list: D000959:Antihypertensive Agents