Pressure and flow in the extracorporeal circuit

The impact of altered pressure and flow in the extracorporeal circuit on dialysis efficacy as a result of increased hematocrit is discussed based on known properties of blood, publications and measurements not yet published by the author. An increase of hematocrit from 0.35 to 0.45 is accompanied by a 3 to 5% reduction of dialysis efficacy as measured by urea elimination. This can be compensated by an increase of dialysis time or blood flow. It is concluded that the alteration of physical parameters does not restrict the normalization of hematocrit. The control of erythropoietin dosing by predialysis hematocrit, however, should be revised.