ULTRASOUND ZOOM
The VExUS Score: Fluid Status, Reconsidered By Ernesto H. Weisson, BS UM Miller School of Medicine
UM Miller School of Medicine
UM Miller School of Medicine
CLINICAL PROBLEM
Proper evaluation of fluid status is imperative to the management and outcome of patients in the emergency department (ED), especially in cases of septic shock, congestive heart failure or acute renal failure. Traditionally, point-of-care ultrasound (POCUS) has been used to assess the inferior vena cava (IVC) for an estimation of fluid status and responsiveness. However, relying exclusively on the IVC diameter and collapsibility has been shown to be insensitive for identifying fluid tolerance in critically ill patients. Like central venous pressure, estimation of the IVC is not a reliable measure of preload in the left ventricle. The IVC might be dilated in various euvolemic conditions, including pulmonary hypertension and valvulopathies, and it might also be dilated as normal physiologic variance in trained athletes. Another drawback of estimating fluid status only from the IVC is that this ignores the amount of congestion in other vital organs such as the lungs, liver, kidneys and gastrointestinal tract.
THEORETICAL CONSTRUCT
The Venous Excess Ultrasonography Score (VExUS) is a 4-step protocol that not only evaluates the presence of congestion in the IVC, but also assesses the severity of congestion in three target organs: the liver, the gut and the kidneys. Emergency physicians can easily utilize this protocol to guide fluid management in their patients. For example, a positive VExUS score might suggest conservative fluid administration or lead to the administration of diuretics and vasopressors.
HOW TO PERFORM A VEXUS EXAM
In preparation, the patient should lie supine with the head of the bed lowered to 0º and legs bent to relax the
Edited by Leila Posaw, MD, MPH
Emergency Ultrasound Faculty, Jackson Memorial
abdominal wall. The operator should be positioned on the patient’s right side to facilitate simultaneous scanning and manipulation of the controls. A curvilinear probe will result in a higher resolution of the vessels, but a phased array probe may be used as well. You will need an ultrasound system with color Doppler and pulse wave Doppler capabilities to perform a successful exam.
Step 1 – IVC assessment (B-mode)
Where to look: Place the probe on the patient in the subxiphoid location in the sagittal plane. You should see the IVC entering the right atrium. The hepatic vein may be seen entering the IVC. What to look for: The diameter of the IVC is commonly measured approximately 3-4 cm from the junction of the IVC and the right atrium, or 1-2 cm caudal to the confluence of the hepatic vein and the IVC. If the diameter is < 2 cm, there is no congestion. If the VExUS score is 0, and you do not need to proceed further. If the diameter is > 2 cm, congestion is present. Further examination is necessary to determine the severity of congestion and VExUS scores 1-3. This is described in the following steps.
Venous congestion can first be appreciated in the IVC: its size increases proportionally to CVP until it reaches its maximum dilation. Pressure is then transmitted in a retrograde fashion through the veins to the abdominal organs.
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By Duyen Vo, BS
By Joshua Goldstein, MD
Step 2: Hepatic vein assessment (B-mode, color mode, pulsed wave Doppler mode)
Where to look: Any of the three hepatic veins (right, middle and left) can be evaluated. However, the middle and right hepatic veins are easier to obtain, as they are less likely to be obscured by bowel/stomach gas. First, find the hepatic veins in B-mode. Place your probe in the right upper quadrant, fanning anteriorly and posteriorly. The hepatic veins are thin walled and communicate with the IVC. In the transverse view, the confluence forms the “Playboy Bunny” sign (Fig. 1). Next, assess the vessels with color Doppler. The veins should be blue (flow away from the probe). Finally, place the pulsed wave Doppler gate in the hepatic vein proximal to where it enters the IVC.
EMpulse Spring 2021
