Arterial Resistivity Index

Q: What is Arterial Resistivity Index (Resistance Index) (RI)?

Answer:  RI is a measure of pulsatile blood flow that reflects the resistance to blood flow caused by microvascular bed distal to the site of measurement. It is obtained by doppler ultrasound signals. Normal adult value is 0.6-0.7.

Clinical significance: RI is increasingly been used in various disease processes involving kidney (see references), particularly in post kidney transplant. RI above 0.8 co-relates with increase mortality.


#Nephrology
#transplant


References/further readings:

1. Saracino A, Santarsia G, Latorraca A, Gaudiano V. Early assessment of renal resistance index after kidney transplant can help predict long-term renal function. Nephrol Dial Transplant 2006; 21:2916–2920

2. Dewitte A, Coquin J, Meyssignac B, Joannès-Boyau O, Fleureau C, Roze H, et al. Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury. Crit Care 2012; 16:R165.

3. Le Dorze M, Bouglé A, Deruddre S, Duranteau J. Renal Doppler ultrasound: a new tool to assess renal perfusion in critical illness. Shock 2012; 37:360–365

4. Darmon M, Schortgen F, Vargas F, Liazydi A, Schlemmer B, Brun-Buisson C, et al. Diagnostic accuracy of Doppler renal resistive index for reversibility of acute kidney injury in critically ill patients. Intensive Care Med 2011; 37:68–76

5. Kaiser C, Götzberger M, Landauer N, Dieterle C, Heldwein W, Schiemann U. Age dependency of intrarenal resistance index (RI) in healthy adults and patients with fatty liver disease. Eur J Med Res 2007; 12:191–195