PURPOSE:Vascular pedicle width has been shown to be a good indicator of intravascular volume status in critically ill patients. Which of the anatomic structures comprising the vascular pedicle accounts for this correlation is uncertain. We conducted this study 1) to distinguish the individual components of the vascular pedicle using CT scanning and 2) to evaluate if their dimensions correlated with the overall vascular pedicle width and central venous pressure.
METHODS:Critically ill adult patients who had had chest CT scans while they were in an intensive care unit were included in the study. Patients who did not have chest radiographs on the same day as chest CT were excluded. Cross-sectional diameters of superior vena cava, right brachiocephalic vein, azygous vein, ascending aorta and descending aorta were measured by a board-certified intensivist. We also measured the distance between the inner equatorial point of the descending aorta and the inner equatorial point of the SVC and called it the thoracic intervascular separation. Vascular pedicle width was measured using closest temporal supine chest radiograph. All measurements were standardized using the intercostovertebral joint distance at the level of the carina. Central venous pressures were determined from review of the medical record. We calculated correlations of cross-sectional areas of veins with the vascular pedicle width and central venous pressure.
RESULTS:29 eligible patients were included in the study. We observed a moderate degree of statistically significant correlation between the vascular pedicle width and the sizes of various vessels and the thoracic vascular separation. These correlations persisted for venous structures after measurements were standardized for body habitus.We also observed a significant correlation between cross-sectional diameter of the azygous arch on chest CT and central venous pressure.
CONCLUSION:Sizes of major thoracic vessels, especially the right brachiocephalic vein, are indeed correlated with width of the thoracic vascular pedicle.
CLINICAL IMPLICATIONS:These findings may provide useful insight into more accurate use of the vascular pedicle width in predicting intravascular volume status in critically ill patients.
DISCLOSURE:Siddharth Singh, No Financial Disclosure Information; No Product/Research Disclosure Information