The IVC view (4)

M Mode of IVC
M Mode of IVC

Most EPs do not calculate the collapse index, as a more qualitative approach is equally useful in the acute setting. A dilated non-collapsing IVC implies that the patient is well filled or over filled, or that there is an obstructive aetiology, whereas a narrow fully collapsing IVC suggests an under-filled patient where aggressive fluid resuscitation is required, and points towards hypovolaemia as the likely cause. It is important to remember that these rules about the IVC are rules of thumbs and that there are circumstances where they will not apply. In a fit, healthy person, the IVC collapse can be greater than half due to the mechanics of respiration on the thorax. Patients with right sided heart failure can have a fixed & dilated IVC despite being hypovolaemic

If it is required to calculate the collapse index, this is best carried out using M mode. M stands for measurement (B for brightness). Using M mode calculations at the POA of minimal and maximal diameter can be made across the proximal IVC.

Learning bite

A dilated non-collapsing IVC implies that the patient is well filled or over filled, or that there is an obstructive aetiology, whereas a narrow fully collapsing IVC suggests an under-filled patient