Distensibility Index of Inferior Vena Cava
The Distensibility Index of Inferior Vena Cava (dIVC) it’s the amount of increase of vena cava diameter after inspiration on a mechanical ventilated patient. This increase will rise when preload is reduced and so can be used to know when a patient its volume responsive. It doesn’t give CVP or the preload of the right heart, but only if it is responsive to more volume.
- On a subcostal window, measure the maximum IVC diameter on inspiration (dI) and the minimum IVC diameter on expiration (dE).
- Calculate the dIVC using the following formula:
Conditions and caveats
- The patient must be on volume control ventilation, with tidal volume of about 8,5ml/Kg, breathing rate of 15 and PEEP of 4 mmHg.
- There shouldn’t be abdominal hypertension, cardiac arrhythmias or cardiopulmonary disease, pending more studies
- It must be possible to do a echocardiogram by subcostal approach, so it can’t be used on the very obese or after an laparotomy
- The first study was done on a reduced number of patient. The followup studies were only done on patients with subarachnoid hemorrhage and on renal replacement therapy
Respiratory changes in inferior vena cava diameter are helpful in predicting fluid responsiveness in ventilated septic patients; Barbier C, Loubières Y, Schmit C, et al; Intensive Care Med; 2004;30(9):1740–6 ↩