Table 1.

Utility and Limitations of Various Sonographic Applications in the Assessment of Fluid Status

Sonographic Application	Key Diagnostic Information	Limitations and Pitfalls
Lung ultrasound	Left-sided cardiac pressures	•Technical errors, such as poor transducer alignment and misidentification of pleural line, especially in obese individuals •B-lines are not specific for pulmonary edema •Variations in scanning protocols throughout the literature
IVC	Right-sided cardiac pressures	•Numerous technical challenges, including a cylinder effect and misidentification of the vessel •IVC can be dilated without elevated right atrial pressure in trained athletes •IVC can be collapsed despite elevated right atrial pressure in intra-abdominal hypertension •Minor changes in diameter can be difficult to appreciate while monitoring a response to therapy; the degree of collapse is influenced by the strength of breath •Cannot differentiate pressure and volume overload (same applies to VExUS)
Hepatic vein Doppler	Quantification of systemic venous congestion and guide decongestive therapy	•Prone to misinterpretation without simultaneous ECG tracing •Influenced by arrhythmias, right ventricular systolic function, and local factors, such as liver cirrhosis
Portal vein Doppler	Quantification of systemic venous congestion and guide decongestive therapy	•Not reliable in patients with cirrhosis and portal hypertension •Can be pulsatile at baseline in thin individuals without elevated right atrial pressure
Kidney parenchymal vein Doppler	Quantification of systemic venous congestion and guide decongestive therapy	•Technically challenging compared to above vessels •Improvement with decongestion is delayed (compared to the portal vein) when interstitial edema is present •Limited data in advanced CKD and kidney transplant

Note: Point-of-care cardiac ultrasound is an integral component of a bedside hemodynamic assessment. However, it is beyond the scope of this review and, hence, is not included here.

Abbreviations: CKD, Chronic kidney disease; ECG, electrocardiogram; IVC, inferior vena cava; VExUS, venous excess Doppler ultrasound.