A novel method for dry weight assessment in hemodialysis patients: utilization of inferior vena cava flat ratio to correct for individual variations in vessel diameter.

Measurement of the inferior of vena cava (IVC) diameter by ultrasonography (US) has been shown to be useful for assessing dry weight (DW) in hemodialysis (HD) patients. We have previously observed some cases in which the IVC diameter differed depending on whether measurements were obtained from sagittal or cross-sectional images. Thus, in the present study we introduce a new concept, the flat ratio, to define the magnitude of IVC deflation. The flat ratio of the IVC (F-IVC) is determined from cross-sectional ultrasonographic images of the IVC. The present study showed that F-IVC is significantly correlated with changes in body weight (DeltaBW(%)). Similarly, the change in F-IVC (DeltaF-IVC) during HD is correlated with DeltaBW(%) but not with changes in systolic or diastolic blood pressure during HD. The results of the present study suggest that F-IVC measurement can serve as a useful tool for DW assessment.