Effect of Dynamic Circuit Pressures Monitoring on the Lifespan of Extracorporeal Circuit and the Efficiency of Solute Removal During Continuous Renal Replacement Therapy

Abstract

Objective: To observe the effects of dynamic pressure monitoring on the lifespan of the extracorporeal circuit and the efficiency of solute removal during continuous renal replacement therapy (CRRT). Materials and Methods: A prospective observational study was performed at the West China Hospital of Sichuan University in the ICU. Analyses of the downloaded pressure data recorded by CRRT machines and the solute removal efficiencies, calculated by 2^*Ce/(Cpre+Cpost), where Ce, Cpre, and Cpost are the concentrations of the effluent, pre-filter blood, and post-filter blood, respectively, were performed. Samples were collected at 0, 2, 6, 12, and 24 h when continuous veno-venous hemodiafiltration (CVVHDF) was used after the initiation of CRRT. Measurements in concentrations of creatinine, blood urea nitrogen, and β2-microglobulin in the plasma and effluent were recorded. Results: Extracorporeal circuits characterized by moderate-to-severe (M-S) access outflow dysfunction (AOD) events, defined as access outflow pressure less than or equal to -200 mmHg for more than 5 min, had shorter median lifespans with no anticoagulation (32.3 vs. 10.90 h, P = 0.001) compared with the no M-S AOD events group. The significant outcome also existed in regional citrate anticoagulation (RCA) (72 vs. 42.47 h, P = 0.02). Moreover, Cox regression analysis revealed that the lack of M-S AOD events, RCA, or CVVHDF independently prolonged the circuit lifespan. All tested solutes removal efficiencies started to decline at 12 h. Furthermore, efficiencies of all solutes removal dropped obviously at 24 h when TMP ≥ 150 mmHg. Conclusion: RCA and CVVHDF predicted a longer circuit lifespan. M-S AOD events were associated with a shorter circuit lifespan when RCA or no anticoagulant was used. Replacement of extracorporeal circuit could be considered when running time of filter lasted up to 24 h with TMP ≥ 150 mmHg.

Keywords: access outflow dysfunction; circuit pressures; continuous renal replacement therapy; extracorporeal circuit failure; solute removal efficiency.

Figure 1

Numbers of CRRT episodes enrolled in the study, assigned to different extracorporeal circuit failures group.

Figure 2

Dynamic mean pressure curve of every minute over time by early, intermediate, and late extracorporeal circuit failures. (A) Access outflow pressure (AOP). (B) Pre-filter pressure (PFP). (C) Effluent pressure (EP). (D) Return inflow pressure (RIP). (E) Transmembrane pressure (TMP). Shaded areas = 95% confidence of the mean. Lifespan of the early group ended at 11 h, the intermediate group ended at 23 h, and the late group ended at 24 h. AOP, PFP, EP, RIP, and TMP are the average values of each pressure minute.

Figure 3

Solute removal efficiency at different times.

Figure 4

Solute removal efficiency in different TMPs groups at 24 h.