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The Speed of Sound

The Speed of Sound

How to Assess Volume Status with VExUS

Butts, Christine MD

doi: 10.1097/01.EEM.0000800480.73682.84
    ultrasound, VExUS, venous congestion
    ultrasound, VExUS, venous congestion:
    Image 1. IVC as seen from the subxiphoid approach. The IVC can be seen coursing toward the right atrium (RA). The main hepatic vein (arrow) can be seen near its junction with the IVC. Note the location where the diameter should be measured (arrowhead).
    Figure
    Figure

    The VExUS protocol uses a handful of ultrasound measurements to estimate the degree of venous congestion at the organ level. The authors of this protocol theorized that they can get a better picture of the patient's true volume status by expanding beyond just an evaluation of the inferior vena cava (IVC).

    The protocol uses two components—evaluation of the IVC and assessment of the hepatic vein. (See diagrams on how to perform and interpret the VExUS protocol in last month's column at http://bit.ly/EMN-SpeedofSound.) The IVC is typically found by placing a low-frequency transducer (either the phased array or curvilinear transducer) in the subxiphoid area, in the long axis with the indicator pointing toward the patient's head. (See image 1B at http://bit.ly/SpeedofSoundExtras.) The transducer is then swept or angled toward the patient's right until the IVC comes into view. (Image 1.) Rocking the transducer so that you are aiming toward the patient's head will often bring the IVC better into view.

    Once a good view of the IVC is obtained, it should be measured a few centimeters distal (caudal) to the main hepatic vein. If the main hepatic vein is not visualized in this position, you can estimate the correct location by measuring 3-4 cm from the junction of the right atrium. The maximum diameter of the IVC should be sought.

    If the maximum diameter of the IVC is less than 2 cm, then for the purposes of the VExUS protocol, the overall score is 0, and there is no significant venous congestion. If the maximum diameter is greater than or equal to 2 cm, however, then the protocol continues.

    The hepatic veins can sometimes be found from the position described above to examine the IVC. (Image 1.) If they are not seen in this view, they can also often be found from a right flank approach. (Image 2.) (Watch a video of this at http://bit.ly/VideosSound.) Incidentally, this view can also be used to find the IVC when it is not seen from an anterior approach.

    Figure
    Figure:
    Image 2. Hepatic veins as seen from the flank approach. The main hepatic vein (arrow) can be seen near its junction with the IVC.
    Figure
    Figure:
    Image 3. Hepatic vein waveforms. Normal flow pattern with large systolic wave (S) followed by a smaller diastolic wave (D).

    A low-frequency transducer should be placed in a long axis orientation in the right anterior axillary line near the lower rib margin. (See image 2B at http://bit.ly/SpeedofSoundExtras.) This is roughly the same spot you would use for a FAST exam. Once the typical FAST view comes into focus, tilt your transducer so that you are aiming more toward the anterior abdominal wall. The hepatic veins will often be seen in this view as they course through the liver toward the IVC.

    Place your Doppler gate over the hepatic vein to generate a waveform. A normal pattern shows a large systolic wave followed by a smaller diastolic wave. As congestion increases, the diastolic wave will become larger than the systolic (mildly abnormal), followed by systolic reversal (severely abnormal). (Image 3.)

    Next month: The last two pieces of the protocol and how to put it all together.

    Find more photos, diagrams, and a video showing how to use the VExUS protocol on EMN's website: http://bit.ly/SpeedofSoundExtras.

    Dr. Buttsis the director of the division of emergency ultrasound and a clinical associate professor of emergency medicine at Louisiana State University at New Orleans. Follow her on Twitter@EMNSpeedofSound, and read her past columns athttp://bit.ly/EMN-SpeedofSound.

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