Optimum Conditions for the Efficacy and Safety of Cryofiltration Apheresis: An Analysis of Circuit Temperatures Depending on Plasma Flow Rate and Cooling Coil Lengths/Turns

摘要

A system providing both appropriate cooling and warming are needed for the efficacy and safety of cryofiltration (CF) plasmapheresis. We measured some points of CF circuit temperatures with varying plasma flow rates (Q(P) = 10-40 mL/min) and the numbers of connecting cooling coils (one or two) under the conditions of blood flow rate (Q(B)) 100 mL/min with 7700-mm coil length, 19 turns, and 50-mL priming volume. We measured the respective temperatures of each point of starting/returning for an extracorporeal circuit (T-A/T-V), intracooling coil (T-C), and post-plasma fractionator (PF) (T-PF). The subtraction of T-V from T-A (Delta T) was used as an indicator of safe return. There were no significant differences in T-C, T-PF, or T in accordance with each Q(P) between that of one and two coils. All of the T-c values under the condition Q(P) <= 20 mL/min achieved <4 degrees C. The T-PF under the condition Q(P) >= 20 mL/min was not significantly different compared to that of Q(P) 30 mL/min (the lowest condition). Although the Delta T increased depending on the Q(P) increase, the Delta T under the condition Q(P) <= 15 mL/min was not significantly different from that of the control (one-way double-filtration plasmapheresis [DFPP]) group. We conclude that (i) one coil is enough for effective cooling in CF, and (ii) an ideal Q(P) that fulfills the required conditions for both effective cooling and sufficient warming of returning fluid does not exist, but Q(P) from 15 to 20 mL/min may be a relevant range.