Objectives: To study hemodynamic changes within continuous renal replacement therapy circuits and evaluate their relationship with continuous renal replacement therapy longevity. Design: Analysis of downloaded variables recorded by continuous renal replacement therapy machines during multiple episodes of clinical care. Setting: Tertiary ICU in Melbourne, Australia. Patients: Cohort of 149 ICU patients: 428 episodes of continuous renal replacement therapy. Interventions: None. Measurements and Main Results: Indices of continuous renal replacement therapy function representing 554,991 minutes were assessed including blood flow, access pressure, effluent pressure, prefilter pressure, and return pressure. We defined three patterns of artificial kidney failure: early (≤ 12 hr), intermediate (> 12–24 hr), and late (> 24 hr) in 35%, 31%, and 34% of circuits, respectively. Mean access pressure in late artificial kidney failure was 7.5 mm Hg (7.1–7.9 mm Hg) less negative than early failing circuits and pressures demonstrated lower variability in such late failing circuits. Access dysfunction, defined as access pressure less than or equal to –200 mm Hg occurred in the first 4 hours in 118 circuits (27%) which had a shorter (median [interquartile range]) life at 12.9 hr [5.5–21.3 hr]) hours than access dysfunction-free circuits (18.8 hr [10.1–33.4 hr]; p < 0.0001). Multivariate analysis found the first occurrence of access dysfunction (as a time-varying covariate) was independently associated with increased hazard of subsequent failure (hazard ratio, 1.75; 1.36–2.26). Classification and regression tree analysis of summary pressure indices in the first 2 hours confirmed minimum access pressure to be a significant predictor, as well as indices of transmembrane pressure and return pressure. A pressure-based predictor correctly identified early and late failing circuits (86.2% and 93.6% specificity, respectively). Conclusions: Access dysfunction is a predictor of continuous renal replacement therapy circuit failure. Future monitoring of continuous renal replacement therapy hemodynamics may facilitate remedial actions to improve circuit function.

<b><i>Title:</i></b> Low blood flow continuous veno-venous haemodialysis (CVVHD) compared with higher blood flow continuous veno-venous haemodiafiltration (CVVHDF): effect on alarm rates, filter life, and azotaemic control. <b><i>Introduction:</i></b> Continuous renal replacement therapy (CRRT) can be delivered via convective, diffusive, or mixed approaches. Higher blood flows have been advocated for convective clearance efficiency and promotion of filter life. It is unclear whether a lower blood flow predominantly diffusive approach may benefit filter life and alarm rates. <b><i>Materials and Methods:</i></b> Sequential cohort study of 284 patients undergoing 874 CRRT circuits from January 2015 to August 2018 in a single university-associated tertiary referral hospital in Australia. Patients underwent a protocol of either CVVHDF at blood flow 200–250 mL/min or CVVHD at blood flow 100–130 mL/min. Machine and patient data were analysed. Outcomes of azotaemic control, filter life, and warning alarm rates were log transformed and analysed with mixed linear modelling with patient as a random effect. <b><i>Results:</i></b> Both groups had similar azotaemic control (effect estimate on log creatinine CVVHD vs. CVVHDF 1.04 [0.87–1.25], <i>p</i> = 0.68) and median filter life (CVVHDF 16.8 [8.4–90.5] h and CVVHD 16.4 [9.4–82.3] h, <i>p</i> = 0.97). However, circuit pressures were less extreme with a narrower distribution during CVVHD. Multivariate analysis showed CVVHD had a reduced risk of warning alarms (incidence risk ratio [IRR] 0.51 [0.38–0.70]) and femoral access placement also had a reduced risk of alarms (IRR 0.55 [0.41–0.73]). <b><i>Conclusion:</i></b> Low blood flow CVVHD and femoral vascular access reduce alarms while maintaining azotaemic control and circuit patency thus minimizing bedside clinician workload.

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