Associations between fluid removal and number of B-lines, peak early mitral inflow wave velocity, and inferior vena cava dimensions in hemodialysis patients

Background: The inferior vena cava (IVC) dimensions represent the right ventricular preload, whereas the peak early mitral inflow wave velocity (peak E-velocity) represents the left ventricular preload. On the other hand, B-lines represent extravascular lung water. The aim of this study was to evaluate possible acute changes in the IVC dimensions, peak E-velocity, and number of B-lines during hemodialysis therapy. Methods: A total of 55 consecutive patients receiving maintenance hemodialysis were enrolled in this study. We performed echo-graphic examinations at three time points (just after the start, during the middle, and just before the end of the hemodialysis therapy). We then investigated the changes in the IVC dimensions, peak E-velocity, and number of B-lines. Results: The peak E-velocity decreased from 80 ± 26 cm/s at the start of the therapy to 58 ± 22 cm/s during the middle and 51 ± 21 cm/s at the end of the therapy. The IVC dimensions also decreased from 15 ± 4 mm at the start of the therapy to 12 ± 3 mm during the middle and 11 ± 3 mm at the end of the therapy. The number of B-lines also decreased from 12 ± 5 at the start of the therapy to 9 ± 4 during the middle and 5 ± 3 at the end of the therapy. The changes in the peak E-velocity and IVC dimensions were significantly greater during the first half of the dialysis period than during the second half of the dialysis period (P < 0.0001 and P < 0.0001, respectively). On the other hand, the changes in the number of B-lines during these periods were significantly smaller during the first half of the dialysis period than during the second half of the dialysis period (P = 0.0016). Conclusions: We showed that the peak E-velocity and the IVC dimensions were reduced mainly during the first half of the dialysis period, while the number of B-lines showed a significant decrease mainly during the last half of the dialysis period. Even if the IVC dimensions are reduced sufficiently, caution is needed as lung congestion may still exist.