Calculation of Absolute Blood Volume Using Intermittent Infusion Hemodiafiltration

The absolute blood volume of dialysis patients at the start of treatment can be calculated using a method that combines continuous relative blood volume measurement and dialysate infusion. In this study, we applied this method to patients undergoing intermittent infusion hemodiafiltration. The initial absolute blood volume was measured based on the relative blood volume changes observed during each of the five intermittent dialysate infusions (dilutions). Initial absolute blood volumes, determined via the first to fifth dilutions, were 4,288 ± 900, 4,377 ± 1,476, 4,170 ± 1,037, 4,009 ± 951, and 3,871 ± 929 ml (specific volumes were 79.5 ± 12.5, 81.2 ± 20.9, 78.2 ± 15.8, 75.1 ± 13.4, and 72.7 ± 13.9 ml/kg). The final absolute blood volumes were 3,813 ± 857, 3,953 ± 1,430, 3,764 ± 1,034, 3,611 ± 919, and 3,488 ± 908 ml (specific volumes were 71.1 ± 11.5, 73.0 ± 20.4, 70.3 ± 15.5, 67.3 ± 12.7, and 65.2 ± 13.2 ml/kg). The initial absolute blood volume measured using the fifth dilution was significantly lower than that of the first dilution ( p < 0.05). The use of intermittent infusion hemodiafiltration, along with relative blood volume measurement, is an easy method for determining absolute blood volume.