Using the chest radiograph to determine intravascular volume status: the role of vascular pedicle width

Due to concerns about the efficacy and safety of using pulmonary artery catheterization to evaluate hemodynamic status, noninvasive diagnostic testing has gained increased importance. This article focuses on both the supportive evidence and the limitations of applying the vascular pedicle width (VPW), which is the mediastinal silhouette of the great vessels, as an aid in the assessment of patients' intravascular volume status. The objective measurement of the VPW obtained from either upright or supine chest radiographs (CXRs which are often already available though not fully utilized) can increase the accuracy of the clinical and radiographic assessment of intravascular volume status by 15 to 30%, and this value may be even higher when VPW is used serially within the same patient. Regardless of the presence or absence of pulmonary edema, the best VPW cutoff for differentiating a high vs normal to low intravascular volume status is 70 mm. Patients with a VPW of > 70 mm coupled with a cardiothoracic ratio of > 0.55 are more than three times more likely to have a pulmonary artery occlusion pressure > 18 mm Hg than are patients without these radiographic findings. We suggest a management algorithm for utilizing the VPW, and whether or not such an approach will offer superior patient outcomes requires prospective investigation. Reappraisal of the VPW and other roentgenographic signs should be incorporated into newly implemented studies of the Swan-Ganz catheter, ICU echocardiography, portable CT scans, and other costlier technologies. While such investigations may refine the optimum application of the portable CXR, conventional and digital supine radiographs should retain an important role in the diagnosis and management of critically ill patients. Lastly, the measurement of the VPW should be incorporated into the training of chest clinicians and radiologists.