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5. Renal Hemodynamics

Renal Venous Congestion

Renal venous congestion can be evaluated by looking at the intrarenal venous Doppler tracings that occur below the baseline. For more indepth details, make sure to read our complete article on the VExUS ultrasound score to help you predict venous congestion.

Below is a quick summary on how to interpret the intravenous venous Doppler tracings:

Normal Intrarenal Vein
Doppler

Normal Renal Vein Doppler
Renal Doppler Grade 0

Mild Intrarenal Vein
Abnormality

Mild Renal Vein Abnl
Renal Doppler Grade 1

Severe Intrarenal Vein
Abnormality

Severe Renal Vein Abnl
Renal Doppler Grade 2
Categories
5. Renal Hemodynamics

Renal Resistive Index (RRI)

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

Normal Renal Doppler - Resistive Index and Venous
Categories
5. Renal Hemodynamics

Renal Hemodynamics

You can measure the renal arterial flow for renal resistive index or renal venous flow to assess for venous congestion. Both arterial and venous waveforms can give you significant information to predict Acute Kidney Injury (AKI) or to help limit venous congestion by limiting IV fluid administration.

The good news is that you can usually get the arterial AND venous waveforms in one tracing which we will show you exactly how to do below!

Step 1: Place Color Flow Doppler on the Kidney.

Editor’s Note: Make sure to decrease your color Doppler scale to about 12-25 cm/s and increase your color Doppler gain after as needed.

Renal Ultrasound Doppler - Normal

Step 2: Place pulse wave Doppler gate interlobar vessels and activate Doppler

Normal Renal Doppler - Resistive Index and Venous - No measurement done