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.

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<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.

Background: During continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA), blood flow (Qb) might affect vascular access dysfunction (AD) and, thereby, circuit life. Methods: Circuit life and circuit haemodynamics were studied in three intensive care units (ICUs) by analysing hemofilter device data (Prismaflex®, Baxter, Chicago, IL). The three sites shared similar RCA protocols but differed in Qb (120–130 vs 150–200 mL/h). Non-RCA circuits were compared with RCA circuits in which the impact of Qb was also assessed. Results: About 3,981,906 min of circuit pressures were analysed in 2568 circuits in 567 patients. High-Qb RCA was associated with more extreme pressures, and greater AD (IRR 3.7 (1.93–7.08) as well as reduced filter life 21.1 (10.2–42.6) vs 27.0 (14.8–41.6) h). AD in high-Qb RCA circuits was associated with a 49% reduction in filter life, versus 24% reduction in low-Qb RCA, associated with a rise in the rate of increase in transfilter pressure. Conclusions: High-Qb RCA-CRRT was associated with greater access dysfunction, earlier filter loss and increased haemodynamic impacts of access dysfunction, suggesting low-Qb RCA-CRRT may improve circuit mechanics, function and longevity.

<b><i>Introduction:</i></b> Treatment with continuous renal replacement therapy (CRRT) is common during extracorporeal membrane oxygenation (ECMO). Such ECMO-CRRT has specific technical characteristics, which may affect circuit life. Accordingly, we studied CRRT haemodynamics and circuit life during ECMO. <b><i>Methods:</i></b> ECMO and non-ECMO-CRRT treatments in two adult intensive care units were compared using data collected over a 3-year period. A potential predictor of circuit survival identified in a 60% training data subset as a time-varying covariate within a Cox proportional hazard model was subsequently assessed in the complementary remaining data (40%). <b><i>Results:</i></b> Median [interquartile range] CRRT circuit life was greater when associated with ECMO (28.8 [14.0–65.2] vs. 20.2 [9.8–40.2] h, <i>p</i> &lt; 0.0001). Access, return, prefilter, and effluent pressures were also greater during ECMO. Higher ECMO flows were associated with higher access and return pressures. Classification and regression tree analysis identified an association between high access pressures and accelerated circuit failure, while both first access pressures ≥190 mm Hg (HR 1.58 [1.09–2.30]) and patient weight (HR 1.85 [1.15–2.97] third tertile vs. first tertile) were independently associated with circuit failure in a multivariable Cox model. Access dysfunction was associated with a stepwise increase in transfilter pressure, suggesting a potential mechanism of membrane injury. <b><i>Conclusion:</i></b> CRRT circuits used in conjunction with ECMO have a longer circuit life than usual CRRT despite exposure to higher circuit pressures. Markedly elevated access pressures, however, may predict early CRRT circuit failure during ECMO, possibly via progressive membrane thrombosis as evidenced by increased transfilter pressure gradients.