Correlation between Central Venous Pressure and Inferior Vena Cava Sonographic Diameter; Determining the Best Anatomic Location.

Introduction: The correlation of central venous pressure (CVP) with inferior vena cava (IVC) sonographic diameter has been reported in several studies. However, few studies have attempted to find the best anatomic location of measurement. Therefore, the purpose of this study was determining the best anatomic location to find precise correlation between CVP and IVC diameter using transesophageal echocardiography (TEE).

Methods: In the present diagnostic accuracy study, patients in need of central venous catheterization and TEE were enrolled. Maximum diameter of IVC were measured during expiratory phase of respiratory cycle at the level of diaphragm, 2cm above the diaphragm and at the point of entry into the right atrium using SonoSite TEE device. CVP was measured using an electronic transducer connected to the central venous line. The best location for sonography was determined via calculating and comparing area under the receiver operating characteristics (ROC) curve (AUC).

Results: 39 patients were enrolled (53.8% female). Mean CVP was 6.8 ± 1.4 mmHg and 25 (64.1%) patients had normal CVP, while 14 (35.9%) showed elevated CVP (> 6 mmHg). Evaluating AUC showed that IVC diameter (p = 0.01), aorta diameter (p = 0.01) and IVC / aorta ratio (p = 0.004) had acceptable correlation with CVP. Point of entry of IVC into the right atrium with AUC of 0.98 (95% CI: 0.95 - 1.00) was the location of highest correlation with CVP.

Conclusion: Based on the present findings, the IVC sonographic diameter and IVC / aorta ratio had acceptable correlation with CVP at the level of IVC entry into the right atrium.