Thermal effects of different dialysis techniques and blood pump speeds: an in vitro study

Thermal effects have a pivotal impact on hemodynamic stability during dialysis procedures. In contrast to conventional dialysis techniques, there are no data in the literature regarding the thermal energy balance during on-line techniques. Secondly, little data exist on the effect of extracorporeal blood pump speed (EBPS) on thermal energy balance. In this study we assessed, first, relative differences in energy transfer rate (ETR) over the extracorporeal circuit during on-line hemo(dia)filtration (H(D)F) procedures and hemodialysis (HD) at different dialysate temperatures during an in vitro procedure using a blood temperature monitor (BTM). Secondly, we assessed the thermal effects of different blood pump speed (BPS) rates during the various treatment modalities. ETR was different among all treatment modalities (p < 0.05) studied, except for HD at 36.5 degrees C vs. pre-dilution hemofiltration (HF) and post-dilution HDF vs. HD at 37.5 degrees C. ETR had the most negative result, indicating the largest energy loss, during HD at 35.5 degrees C (-58.5.2 +/- 2.6 W), whereas it was almost comparable between pre-dilution HF (-30.7 +/- 4.1 W) and HD at 36.5 degrees C (-35.1.2 +/- 2.4 W). Post-dilution HDF (-17.7 +/- 1.2 W) resulted in an ETR comparable to that of HD at 37.5 degrees C (-15.0 +/- 3.9 W). ETR during post-dilution HF was -43.8 +/- 1.3 W. The thermal effect of the BPS was more pronounced during the procedures with the more negative ETR. In conclusion, on-line techniques and BPS have widely varying effects on ETR during dialysis, which should be considered when the hemodynamic effects among different treatment modalities are compared.