When it is not possible to obtain the subcostal view, it is possible to use the lateral transhepatic view. However, using the percentage variation in IVC size is likely to be more reliable than the absolute diameter alone. It is possible to use both views interchangeably.

The limits of agreement were wide for minimum and maximum inferior vena cava (IVC) diameter with variation of as much as 4 mm in both directions.

However, the limits of agreement were much narrower when the percentage variation in relation to respiration was plotted on the Bland–Altman plot.

After Institutional Ethics Committee approval and informed consent, we obtained 175 paired measurements of the IVC diameter and variation in both the views in adult mechanically ventilated patients.

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