The role of inferior vena cava diameter in the differential diagnosis of dyspneic patients; best sonographic measurement method?

STUDY OBJECTIVE

We aimed to determine the role of inferior vena cava (IVC) diameter in making a differentiation between dyspnea of cardiac (acute heart failure [AHF]) and pulmonary origin. We also attempted to determine the best sonographic method for the measurement of IVC diameter.

METHODS

This prospective observational study was conducted at the intensive care unit of the emergency department of a training and research hospital. This study enrolled patients with the main symptom of dyspnea who were categorized into 2 groups, cardiac dyspnea and pulmonary dyspnea groups, based on the final diagnosis. All patients underwent sonographic measurement of minimum and maximum diameters of IVC, and the caval index (CI) was calculated in both M-mode and B-mode. The sensitivity, specificity, and likelihood ratios (LR) of the IVC values for the differentiation of the 2 groups were calculated.

RESULTS

This study included a total of 74 patients with a mean age of 72.8 years. Thirty-two patients had dyspnea of cardiac origin, and 42 patients had dyspnea of pulmonary origin. The IVC diameter measured with B-mode during inspiration (B-mode i) was the most successful method for differentiation of the 2 groups. B-mode i values greater than 9 mm predicted dyspnea of cardiac origin with a sensitivity of 84.4% and a specificity of 92.9% (+LR: 11.8, LR: 0.16).

CONCLUSION

Sonographic assessment of the IVC diameter may be used as a rapid, readily, nonexpensive, complication-free, and reproducible technique for the differentiation of cardiac and pulmonary causes of dyspnea. B-mode i measurement may be more successful in the differentiation of dyspnea compared with other IVC diameters and calculations.