VALIDATION & PRECISION

Validation of the BCM – Body Composition Monitor

 

All output parameters have been validated against the gold standard reference methods in a number of studies involving more than 500 patients and healthy individuals.

 

These reference methods include:


  • Extracellular Water – bromide dilution
  • Intracellular Water – total body potassium (TBK)
  • Total Body Water – deuterium dilution
  • Lean Tissue Mass – Dual Energy X-ray Absorptiometry (DEXA)
  • Adipose Tissue Mass – 4-compartment modeling, DEXA, air displacement plethysmography and under water weighing
  • Body Cell Mass – magnet resonance tomography, TBK
  • Overhydration – pre and post haemodialysis measurements compared to ultrafiltration volume¹, expert clinical assessment

 

The BCM – Body Composition Monitor is as accurate as the gold standard reference methods in patients and healthies.

 

¹Wabel, P. et al., Accuracy of bioimpedance spectroscopy (BIS) to detect fluid status changes is hemodialysis patients. Poster presentation ERAEDTA 2007.

 

 

A precise “V” for dialysis dose assessment

 

 

The BCM - Body Composition Monitor provides an accurate determination of total body water (TBW) which has been validated against gold standard dilution methods. As TBW is equivalent to the urea distribution volume (V), there is no need for time-consuming kinetic urea modeling or anthropometric equations which can produce erroneous results in extremes of body composition.

 

The BCM - Body Composition Monitor can be used for dialysis dose assessment by providing the input of "V" for the Fresenius Medical Care OCM® option.


BCM
The BCM - Body Composition Monitor assessment of total body water (V) is validated against gold standard reference methods (R² = 0.9).


Accuracy of bioimpedance spectroscopy (BIS) to detect fluid status changes in haemodialysis patients.

 

The validity of absolute changes can be demonstrated with measurements in the same patient before and after haemodialysis treatments.

In 33 patients BCM measurements were performed directly before, directly after, 30 minutes after and 2 hours after a haemodialysis treatment.

The mean ultrafiltration volume was 2.5 ± 0.79 liters over all patients (see Table).

 

The change in the patients’ fluid status induced by the ultrafiltration was accurately reflected in ECW, TBW and OH in the measurement 30 minutes and 2 hours after the end of the treatment (see Table).


Validation

Over the time of a single treatment no appreciable changes in body composition would be expected. It follows therefore that the intracellular water (ICW) and the body composition parameters (fat and LTM) should remain unchanged by the treatment, despite fluid removal.

 

However, immediately at the end of the treatment all three output variables were found to be significantly different. These apparent changes are thought to be the consequence of treatment induced effects, such as vasoconstriction that can lead to inhomogeneous conditions in the patient. Consequently, errors may be introduced when measurements are made either during treatment or immediately after the treatment.

 

30 minutes after the end of the treatment fluid equilibrium was found to be re-established in the patient and no significant changes to the pre treatment values of ICW, LTM and fat were observed.

 

The BCM – Body Composition Monitor precisely reflects changes in fluid status.

To obtain a reliable assessment of the body composition no measurements should be performed immediately at the end of the treatment – it is necessary to wait at least 30 minutes before measuring post dialysis.