Mechanism and prevention of crystal depositions in the circuit using hemofiltration replacement fluid

Abstract

Hemofiltration replacement fluid might deposit crystals in the circuit after being used for a continually long period. In this study, the crystal depositions in the circuit, and the electrolytes compositions and the gas analysis of the fluid in the circuit were investigated under various conditions with the fluid flow rate of 10 ml・min －1 for 96 hrs. The crystals were observed in the outlet of a roller pump, but not in the inlet. The crystals were observed after 48 hrs at the circuit pressure of 100 mmHg, and were increased with the elapsed time. As the stimulation was added to the fluid, because the circuit was compressed with the rotation of the pump, it was considered that the bicarbonate ions might be decomposed to the carbonate ions. Therefore, the crystals of calcium carbonate might be observed in the outlet of the pump. Also, the crystals might grow up big, and be increased with the elapsed time. However, the crystals were decreased with the increase of the circuit pressures. It was considered that the decomposition of bicarbonate ions might be depressed with the circuit pressure of over 100 mmHg, because the PCO 2 was 70〜100 mmHg. The gas analysis changed at every 24 hrs interval, but it was within a constant range for 96 hrs. There was no change on the electrolytes compositions for 96 hrs. Accordingly, as the crystals may flow into the blood, it is recommended that the circuit using hemofiltration replacement fluid should be exchanged before the crystals are deposited.