Ultrasound Assessment of IVC Pressure for Estimating Right Atrial Pressure

Measurement Technique

The American Society of Echocardiography recommends measuring the IVC diameter perpendicular to the long axis, approximately 1-2 cm from the cavoatrial junction, using a phased array or curvilinear probe in the subcostal view 1, 2
The European Heart Journal suggests obtaining measurements in both inspiration and expiration using M-mode for accuracy 1
Evaluate the IVC during a brief sniff maneuver, as normal quiet breathing may not elicit adequate collapse, and calculate the collapsibility index as: (IVCe - IVCi)/IVCe, where IVCe is expiratory diameter and IVCi is inspiratory diameter 1

The American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines provide specific cutoffs for RA pressure estimation, where normal RA pressure (3 mmHg) is indicated by an IVC diameter <2.1 cm with >50% collapse during sniff 1
Elevated RA pressure (15 mmHg) is indicated by an IVC diameter >2.1 cm with <50% collapse during sniff, according to the European Heart Journal 1
Intermediate RA pressure (8 mmHg) is indicated when IVC diameter and collapse don't fit the normal or elevated pattern, as suggested by the European Heart Journal 1

A dilated IVC (>2.1 cm) with minimal respiratory variation indicates right ventricular pressure overload, according to the European Respiratory Journal and Intensive Care Medicine 3, 4
The European Respiratory Journal and Intensive Care Medicine recommend combining IVC findings with RV/LV ratio >1.0 on apical 4-chamber view, paradoxical septal motion, and TAPSE <16 mm to assess right ventricular failure 3, 4
In suspected massive pulmonary embolism, a normal-sized collapsible IVC effectively rules out obstructive physiology, as stated in Intensive Care Medicine 4
Severe hypovolemia presents with a small, collapsing IVC (>50% collapse) accompanied by small cardiac chambers and intraventricular obliteration during systole, according to Intensive Care Medicine 4
A dilated, non-collapsing IVC suggests volume overload or elevated right-sided pressures rather than hypovolemia, as suggested by the European Heart Journal and Intensive Care Medicine 1, 4

The European Heart Journal recommends using the tricuspid regurgitation velocity by continuous wave Doppler and adding the estimated RA pressure based on IVC assessment when calculating RV systolic pressure 5
Report RV systolic pressure only when a complete TR Doppler velocity envelope is present, as stated in the European Heart Journal 5
Integrate other indices of RA pressure when IVC findings are equivocal to upgrade or downgrade the pressure estimate, according to the European Heart Journal 1