Abstract
As negative pressure in the pre-pumping segment of blood lines used for roller pumps in hemodialysis may affect their efficiency, we checked the relationship between negative pressure in the pre-pumping segment and the actual blood flow using heparinized bovine blood (hematocrit=25%). By tightening a screw clamp on the arterial side of a blood line, the pressure in the pre-pumping segment was reduced to -200mmHg. Actual blood flow was reduced by 10% if the original blood flow without negative pressure was 200ml/min. One must be aware of this phenomenon, especially in calculating the in vitro clearance of a dialyzer.
