The Renal Resistive Index is measured by placing the calipers at the Peak Systolic Velocity (PSV) and End Diastolic Velocity (EDV). A renal resistive index (RRI) of >0.7 is predictive of impending Acute Kidney Injury in multiple clinical settings including trauma and critical care (Song 2018).
The Renal Resistive Index is calculated using the following formula:
Renal Resistive Index Forumla: RRI = (PSV – EDV)/PSV
In the example below PSV = 27.26 cm/s and EDV = 13.86 cm/s
Therefore RRI = (27.26 cm/s – 13.86 cm/s) / 27.26 cm/s = 0.49
