Measurement point for the IVC: 2 cm below the junction of the hepatic veins
IVC collapse index (IVC CI) =
= ((maximum diameter of the IVC) - (minimum diameter of the IVC)) / (maximum diameter of the IVC)
where:
• The maximum diameter of the IVC usually occurs during expiration.
• The minimum diameter of the IVC usually occurs during inspiration.
• The diameter of the IVC is affected by positive pressure ventilation.
Interpretation:
• A person with normovolemia has a collapse index of around 50%.
• The greater the collapse index the greater the chances of significant hypovolemia.
• The lower the collapse index the greater the chances of significant hypervolemia.
• There is no consensus for cutoffs to define hyper- or hypovolemia.
• The method is noninvasive and can be used to monitor the patient over time.
