Microcirculation as a novel marker of membrane biocompatibility.

Background: It is possible to consider microcirculation as a kind of "witness" of the complex biological reactions triggered by the dialytic treatment. The reactivity of microcirculation to the dialytic stress may represent a measure of the overall biocompatibility of the membrane. In this study we tested the hypothesis that different synthetic membranes may have different biological effects, particularly related to microcirculation. Subjects and Methods: In this crossover study, we observed 16 chronically hemodialyzed patients. All patients were treated with the EVAL membrane; we recorded the TcPO2 during the second treatment of the week. All patients were then switched to the hf-PS membrane. During the study observation we did not change the dialytic prescription or the pharmacologic treatment. Results: From the beginning of the session until 90', the behavior of TcPO2 is similar for both the membranes. From 120' to the end of the treatment in sessions with the EVAL membrane, the TcPO2 values come back to the starting level, whereas in the treatments with hf-PS the TcPO2, the values remain at a lower level; there was a significant difference between EVAL and hf-PS in the values recorded. Arterial blood gas values of paO2 and paCO2 are quite similar in the treatments with both the membranes, without any significant difference. Conclusions: The analysis of microcirculation by means of TcPO2 measurement is a useful tool to obtain a "clinical" measure of biocompatibility of the dialytic treatment and different membranes may have different impacts on TcPO2.