Extensive Search for Dry Weight: Should We Change the Strategy?

Abstract

Introduction: A wrong estimate of the dry weight in hemodialysis patients increases their morbidity and mortality. The aim of our study was to compare the results of the estimated dry
weight using the clinical examination with the results of the lung ultrasound, impedance measurement, ultrasound of the inferior vena cava and B-type Natriuretic Peptide (BNP) assay.
Methods: A cross-sectional study was conducted in an hemodialysis center at Fez. The estimated dry weight of the patients was evaluated before and 30-60 minutes after the hemodialysis
session using the four above-mentioned methods.
Results: The values, measured by the different techniques used, drop significantly after hemodialysis (p<0.001). The measurement studied before and after the hemodialysis, had shown a
significant correlation between the results of the impedance measurement, lung ultrasound, the
maximum and minimum of the Venous Collapsibility Index (VCI) index diameter as well as
its collapsibility. However, no correlation was found between BNP levels and other methods.
A significant difference between the results provided by the techniques studied and the results
of the clinical evaluation was found in 84.4% of patients. In univariate analysis, only age was
significantly shown as an associated factor with error estimation (p<0.04).
Conclusion: This study is one of the few studies using lung ultrasound to assess the hydration
status of hemodialysis patients. It also showed a good correlation with other methods. The existence of a gap between the subjective and objective target weight suggests the usefulness of a
systematic periodic use of bioimpedance and ultrasound techniques even if clinical symptoms
are absent.