Concentration of elastase measured at inlet (C
) and outlet (C
) and total mass production rate (Mtp) over time (median and interquartile range). Results of generalized estimating equations (symbols: ● no anticoagulation ■ heparin ▲ citrate) for elastase in A. Ci: increases over time, most in the no anticoagulation group (P = 0.002 for interaction). B. Co: increases over time (P = 0.012). C. Mtp: highest in the heparin group (P = 0.049), decreases over time most in the heparin group (P = 0.002 for interaction).