Correlation of Bedside Ultrasonographic Measurement of IVC Diameter and Caval Index with CVP in Spontaneously Breathing and Mechanically Ventilated Patients

Background: One of the important parameters in the hemodynamic evaluation of critically ill patients is central venous pressure (CVP).Sonographic measurement of the inferior vena cava (IVC) diameter and caval index (IVC collapsibility index) is a non-invasive method of estimating the fluid status in critically ill patients.In this study, we aimed to detect the correlation between IVC diameter and caval index with CVP in both spontaneously breathing and mechanically ventilated patients.Methods: The anterior posterior diameter of the IVC just caudal to the confluence of the hepatic veins was measured during inspiration and expiration to calculate the IVC diameter and caval index.CVP was detected in cm H2O.Results: As regard correlation between IVC measurements (IVC diameter and caval index) and CVP, regression coefficients were higher among spontaneously breathing than mechanically ventilated patients.In sedated patients, the mean difference between inspiratory and expiratory IVC diameter is not of clinical significance.The mode of mechanical ventilation and peak inspiratory pressure were insignificant in prediction of CVP.Conclusion: Ultrasonographic assessment of IVC diameter and caval index seems to be a simple and non-invasive method to assess the fluid status in spontaneously breathing patients but its use in mechanically ventilated patients is not helpful.