Komponenten der Bioinkompatibilität der extrakorporalen Hämodialyse des Menschen

Nowadays, bioincompatibility of dialysis materials plays a decisive role in the development of typical, although not specific, chronic complications, observed in patients undergoing chronic hemodialysis. Several parameters are well proven to measure the quantity of bioincompatibility reactions. Well suited for recording the phenomenon of bioincompatibility are the activation of complement (reflected mainly in the plasma levels of the complement component C3a/ C3ades Arg and C5a/C5ades Arg) [5], [9], [42], [70], [109], [110], [112], [144], [193], [197], the grade of activity of the oxidative metabolism of polymorphonuclear neutrophil granulocytes (measurement e.g. with the cytochrome C reduction test) [51], [79], [104], [109], [134], [135], [143], [181], the transient leucopenia in the early phase of hemodialysis procedure [7], [9], [25], [41], [70], [110], [111], [119], [191], [232], [236], [251] and the release of interleukins (e.g. IL-1, IL-6 and TNF) [5], [15], [17], [20], [55], [63], [90], [112], [144], [166], [193], [197], [217]. The body temperature is lower in uremic patients than in healthy people [10], [116], [130], [131], [159], [220], [246]. During hemodialysis a rise in body temperature, such as a febrile or hypertermic reaction, is a well-known phenomenon. Also, an increase of energy turnover is frequently observed in hemodialysis although the energy transfer in the extracorporeal circuit is balanced. Thus, there is neither heat removal nor warming up by the external blood circulation [47], [131], [139], [140], [141], [142], [145], [146], [159], [167], [168], [169], [170], [205], [209], [145], [146]. A baroreflex mediated increase of total peripheral resistance [86], [140] and a febrile reaction through endotoxins in the dialysate [60], [201], [205] were blamed for causing the rise of body temperature and energy turnover. Finally, a complex amount of pyrogens and cryogens and the state of hydratation of the hemodialyzed patient seem to have influence upon the regulation of body temperature. [114], [131]. Moreover, an increased breathing exercise could lead to a raised energy turnover. This could be explained by two phenomenons. 1) An interstitial pulmonary oedema resulting from the sequestration of leucocytes in the pulmonary capillaries could enhance the breathing exercise [140]. 2) The high pCO2 in the bicarbonate dialysis bath fluid [18], and consequently in the arterial blood, could likewise cause an increase in respiratory drive. The attempt to use the body temperature and the energy turnover to measure bioincompatibility of dialysis materials shows that both parameters could merely fulfil this function in a limited manner. These two parameters seem to be less sensitive than the measurement of complement components, interleukins leucocyte count and their oxidative metabolism. Not all the phenomenons of bioincompatibility are able to influence body temperature and energy turnover. The present study points out that neither the activation of the oxidative metabolism of neutrophils nor the transient leucopenia are exclusively linked with a contact to the dialysis membrane. To some extend, the extacorporeal circulation itself, without a contact to a dialysis membrane or the dialysis bath fluid, already leads to the upper mentioned leukopenia and the production of reactive oxygen radicals. The stimulation of the oxidative granulocyte metabolism and the decrease in leucocytes was detected at the sole contact with the tubes of the extracorporeal circuit (regime A), at the contact with the tubes and the dialysis membrane (regime B) and at the contact with the tubes, the membrane and the dialysis bath fluid (regime C), although to somewhat different extends respectively. There is evidence that all components of the extracorporeal circulation have a measurable influence upon the hemostasis of the hemodialysis patient. The efforts to improve bioincompatibility should not only focus on the dialysis membranes, but also on the tubes and the bath fluid as well. The contamination of the dialysis bath fluid with fragments of the bacterial cell membrane like LPS or lipid-A and others, clearly seem to contribute to febrile and other acute phase reactions in hemodialysis patients. It makes sense to pay more attention to the quality of this component and to intensify its controls in routine hemodialysis.