- Though controversial, IVC measurement by ultrasound can estimate volume status, fluid responsiveness, and fluid tolerance
- Can use as a dynamic assessment after intervention such as giving fluids or passive leg raise
- Dynamic changes is probably best measured in intubated patients
- Differentiate causes of shock
- Differentiate causes of shortness of breath
- Establish likelihood of fluid responsiveness
- Assess response to interventions
- Select probe
- Curvilinear or phased array probe
- In subxyphoid cardiac view (epigastric), fan probe laterally to view the IVC draining and identify it draining into the right atrium
- May start with subxyphoid view, place right atrium in center of screen and rotate probe 90 degrees clockwise to find IVC
- Longitudinal view
- M-mode to measure IVC collapse during inspiration or estimation can be made in 2D with IVC in longitudinal axis
- Measure both absolute diameter of IVC and percent collapse during inspiration of spontaneously breathing patients
- Dynamic measurements
- Repeat measurements can be made after passive leg raise or IVF bolus
Classic Ultrasound Findings For Critically Ill Patients
|Disease||IVC||Cardiac||Lung (Phased Array)||Lung (Linear)|
|NL or B-lines||Sliding|
|Tamponade||↑||RA collapse with filling
RV collapse with filling
|PTX||↑||NL or Hyperdynamic||Lung point
|Absent lung sliding|
|Sepsis||↓||Hyperdynamic squeeze||NL (see pneumonia)||Sliding|
|Pneumonia||NL or ↓||Hyperdynamic squeeze||Unilateral B-lines||Sliding|
|Decompensated HF||↑||Mod/Poor squeeze||Bilateral B-lines||Sliding|
|PE||↑||RV > LV
|NL or Unilateral B-lines||Sliding|
Correlations Between IVC Size and CVP
|IVC (cm)||Respiratory Change||CVP (cm H2O)|
Measure 2cm from IVC/RA junction or 1cm from IVC/hepatic vein junction
Pearls and Pitfalls
- Aorta can be confused for IVC, ensure you visualize the vessel entering the atrium
- Ensure the vessel is viewed in full longitudinal axis as being off-center will give falsely narrow measurements
A bedside IVC ultrasound was performed to assess volume status in setting of dehydration. The IVC was identified in longitudinal access. The IVC was neither flat nor plethoric. There was less than 50% collapse with respirophasic measurements. This does not imply that the patient is not volume responsive but rather further testing is needed.
A bedside IVC ultrasound was performed to assess volume status in setting of dehydration. The IVC was identified in longitudinal access. The IVC was flat with over 50% collapse with respirophasic measurements. There was evidence of volume depletion and fluid tolerance.
A bedside IVC ultrasound was performed to assess volume status in setting of fluid overload. The IVC was identified in longitudinal access. The IVC was plethoric with less than 50% collapse with respirophasic measurements. There was evidence of volume overload.
- Life in the Fastlane - SMACC: The Dark Art of IVC Ultrasound
- ACEP Focus On: Inferior Vena Cava Ultrasound
- Dipti A, et al. Role of inferior vena cava diameter in assessment of volume status: a meta-analysis. AJEM. 2012; 30:1414-1419.
- Zhang Z, et al. Ultrasonographic measurement of the respiratory variation in the inferior vena cava diameter is predictive of fluid responsiveness in critically ill patients: systematic review and meta-analysis. Ultrasound Med Biol. 2014. May; 40(5):845-53.
- Goldflam K, et al. Focus on: Inferior vena cava ultrasound. ACEP News. June 2011.