Relationship Between Ventilatory Change of the Inferior Vena Cava and Central Venous Pressure

DOI PubMed
  • Tamaki Shigeru
    Division of Respiratory Disease, Department of Internal Medicine, Jichi Medical School

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Other Title
  • 下大静脈の前後径の呼吸性変動と中心静脈圧

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Ventilatory change of antero-posterior diameter of the inferior vena cava (IVC) was studied by ultrasonography, simultaneously with measurement of central venous pressure (CVP). In normal subjects, the lumen of IVC started to collapse in the late inspiratory phase, reached a minimum diameter at the end of inspiration, and then distending during expiration. IVC lost this physiological dimensional change and was fully distended through the entire course of ventilation when CVP was elevated, with an increase of intrathoracic pressure, as during mechanical ventilation and Valsalva manuever and with right heart failure and pericarditis. From these results, the correlation between Collapsibility Index ([maximal width on expiration-width in maximal collapse on inspiration]/maximal width on expiration) and CVP was studied. Through accumulated results obtained from various respiratory and circulatory patients, the following regression equation was derived. Y=1.043-0.067X+0.001X2, in which n was 48, r=0.73, and p<0.001. In this equation, Y is Collapsibility Index and X is CVP. When CVP is less than 25cm H2O, Collapsibility Index inversely correlates with CVP and is almost zero when CVP is more than 25cm H2O which means that IVC is kept in a fully distended state through entire course of ventilation.<br>From this relationship, it is possible to estimate CVP in various clinical conditions and its alterlation corresponding to reasonable and non-invasive treatment. The clinical significance and its mechanism of the configurational change of IVC are also discussed based on the results obtained through a model experiment designed with a collapsible tube.

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