Merits and limitations of continuous blood volume monitoring during haemodialysis. Summary of the EDTNA/ERCA Journal Club discussion: Winter 2005.

The discussion explored and expanded on the issues raised by Dasselaar et al in their review of the measurement of relative blood volume (RBV) changes during dialysis (NDT 2005). Dialysis machines incorporating blood volume monitoring and control are widely available in Europe. The use of continuous blood volume monitoring (CBVM) to help establish dry weight; problems with CBVM due to connection and use of single needle dialysis; the physiological processes that cause RBV changes during eating, exercise and posture changes; and the application of blood volume based biofeedback control were discussed by participants from ten countries. The 'take-home' messages from the discussion were that CBVM can assist in setting target weight, but must be used together with traditional measures and experience. Biofeedback control may help to achieve symptom-free dialysis, but staff should be prepared to monitor patients systematically for several weeks to obtain individualised settings. Users of CBVM should be aware of factors that can alter the central haematocrit leading to apparent changes in RBV. Practical guidelines should be developed to help staff interpret CBVM data effectively.