Wet or dry in dialysis--can new technologies help?

Whereas clinical assessment remains the mainstay of estimating dry weight in dialysis patients, subtle over- and under-hydration may remain undetected, which may result in increased short- and long-term morbidity. Various technological tools have been developed to aid the clinician in the assessment of fluid state in dialysis patients. Chest X-ray is useful in clinical management, but does not fulfill the need for rapid, noninvasive bedside testing. Vena cava echography provides a reliable estimation of right atrial pressure and was shown to be useful in the clinical management of dialysis patients, but the timing of measurement is of critical importance. New developments in bioimpedance techniques hold great promise for the routine application of this technique in the assessment and follow-up of hydration state. Cardiac biomarkers have a strong prognostic value, and may reflect overhydration indirectly because of its effect on left ventricular stress. Blood volume monitoring as a tool to assess dry weight needs further validation and standardization. Summarizing technological tools may certainly aid the clinician in the assessment of fluid state, but should always be interpreted in the clinical context of the patient. Controlled studies are needed to definitively establish the role of technological tools in detecting dry weight.