The effect of CVVHD and endotoxin on the oxidative burst, adhesion molecules and distribution in tissues of...

Extracorporeal circulation, such as cardiopulmonary bypass and haemodialysis, has been associated with an activation of the immune system, especially the granulocytes. Continuous veno-venous haemodiafiltration (CVVHD) is used in critically ill septic patients. During CVVHD cytokines are excreted in the ultrafiltrate. But when the membranes used in CVVHD are cultured with granulocytes, the granulocytes are slightly activated. This effect is potentiated by endotoxin. We therefore, in vivo, compared the effect on granulocyte activation of CVVHD with an endotoxin group and a control group.

Thirty-one pigs were anaesthetized and mechanically ventilated. In ten pigs CVVHD was performed. Eleven pigs received an infusion of Escherichia coli endotoxin 30 mu/kg(-1) and ten pigs served as a control group. The adhesion molecules CD18 and CD62L were measured using monoclonal antibodies. The oxidative burst activity was assayed as superoxide dismutase-inhibitory reduction of cytochrome c. The number of granulocytes in peripheral blood and in the lungs and liver were counted.

The infusion of endotoxin was followed by granulocytopenia, reduced oxidative burst activity, increased expression of CD18 and decreased expression of CD62L on granulocytes. Accumulation of granulocytes in liver and lung tissue was also noted in this group. CVVHD was only associated with a non-significant decrease in CD62L expression on granulocytes. It did not affect any of the other measured immunological parameters.

In contrast to endotoxin-induced sepsis, the granulocytes were not activated during CVVHD.