Fig. 6
Final blood concentration of targeted molecules by clearance and operating time of hemofiltration. Assuming no generation of targeted molecules, the figure estimates the blood concentration at the end of hemofiltration expressed as a percentage of the initial concentration. These numbers are calculated by clearance (mL/kg/min) and operating time (h) of hemofiltration. The calculation was derived from the following general equation including clearance, operation time of hemofiltration, and the blood concentration of molecules [40]: \( C={C}_0\cdot {e}^{-\frac{K\cdot t}{V}} \), where C is the blood concentration at the end of hemofiltration and C 0 (at the beginning) is set at 1. V (mL/kg) is the total body water assumed that the body was 60 % water by weight (600 mL/kg), t is operational time (min) of hemofiltration, and K (mL/kg/min) is the clearance of investigated filters that can be replaced with SC (sieving coefficient) × Qf (filtration rates, mL/kg/min) [41] in the filtration technique. A period of time was given as a range of 0–2, 2–4, 4–6, 6–10, and 10–infinity hours in this figure (expressed as gray color gradation). Marks numbering from 1 to 8 displayed referenced reports on IL-6 removal; 1 and 2 are referring to two differing settings of our study (1 is for standard volume hemofiltration and 2 is for high-volume hemofiltration); 3, Laurent et al. [19] and 4, Nagashima et al. [20], studies on whole-body ischemia/reperfusion injury; 5, Kellum et al. [34], 6, Bellomo et al. [21], 7, Lu et al. [35], and 8, Rogiers et al. [33], studies on a sepsis animal model. The studies, 1, 2, and 5–8, used the same filter of AN69; therefore, SC was set at 0.3 according to our pilot data. For the other studies, 3 and 4, SC was arbitrarily set at 0.3–1.0 because of the larger porosity of their investigated filters, which are made from high-flux hollow-fibers