Using additional pressure control lines when connecting a continuous renal replacement therapy device to an extracorporeal membrane oxygenation circuit

Safety and Effectiveness of Veno-Venous Extracorporeal Membrane Oxygenation Combined with Continuous Renal Replacement Therapy

Patients receiving extracorporeal membrane oxygenation (ECMO) often suffer from acute kidney injury (AKI), requiring continuous renal replacement therapy (CRRT). In our clinical practice, we connected the inlet line of a CRRT machine to the postoxygenator Luer port and the outlet line to the inlet Luer port of the oxygenator. In this case series, we analyzed the interaction between the two machines. Between December 31, 2017, and December 31, 2019, we enrolled 15 patients from the ICU of the San Matteo Hospital, Pavia, Italy. All of them suffered from severe acute respiratory distress syndrome and AKI stage 3. We analyzed 570 hours of CRRT combined with venovenous ECMO and collected 261,751 CRRT data. No discontinuation of CRRT occurred before 48 hours. Most of the alarms occurred within 24 hours of the connection: 22/10,831 (0.2%) showed an outranged inlet pressure, 11/10831 (0.11%) showed an outranged transmembrane pressure, 14/10,831 (0.13%) showed an outranged inlet pressure, and 138/10,831 (1.27%) an outranged effluent pressure. The rate per minute set for the ECMO circuit was correlated with the inlet (β = 5.38; CI, 95% 1.42-9.35; p = 0.008), transmembrane (β = 4.6; CI, 95% 1.97-7.24; p = 0.001), effluent (β = 3.02; CI, 95% 1.15-4.90; p = 0.002), and outlet pressures (β = 597; CI, 95% 2.31-9.63; p = 0.001) of the CRRT circuit. We reported that our configuration could be safe and effective, however well-designed studies would be beneficial for determining the potential risks and benefits.

Renal replacement therapy in extra-corporeal membrane oxygenation patients: A survey of practices and new insights for future studies

BACKGROUND

Patients under extra-corporeal membrane oxygenation (ECMO) are at high risk of developing acute kidney injury and renal replacement therapy (RRT) is frequently needed. The aim of this study was to explore RRT use in ECMO patients, as no recommendations exist in this setting.

METHODS

An online questionnaire about RRT management in ECMO patients was sent to the members of the ARCOTHOVA (Anesthésie-Réanimation Coeur-Thorax-Vaisseaux) association and to the GFRUP (Groupe Francophone de Réanimation et Urgences Pédiatriques).

RESULTS

Ninety intensivists from adult ICU and twenty from paediatric ICU responded to the questionnaire. RRT use was common as 67% respondents reported that more than 25% of their ECMO patients needed RRT. RRT indications were similar between centres, with persistent anuria (83%), metabolic acidosis (80%), fluid overload (78%) and hyperkalaemia (80%) being the more prevalent. Continuous renal replacement therapy was the preferred technique (97%). Continuous veno-venous haemofiltration was predominant (64%) over continuous veno-venous haemodiafiltration (21%). Unfractionated heparin was employed as first line choice anticoagulation in 61% and regional citrate anticoagulation in 16%. Integration of RRT device directly into the ECMO circuit was the preferred configuration (40%) while parallel systems with separate catheter were used in 30%. When the integrated approach was chosen, RRT device was most frequently connected with inlet and outlet lines after the ECMO pump (58%) and pressure alarms were encountered for 60% of participants.

CONCLUSIONS

Our results highlight the high variability of practice between centres. They suggest the need to compare the integrated and parallel configurations of combining RRT and ECMO.

Acute kidney injury in ECMO patients

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at  https://www.biomedcentral.com/collections/annualupdate2021 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from  https://link.springer.com/bookseries/8901 .

Mathematical modeling of the impact of recirculation on exchange kinetics in tandem extracorporeal membrane oxygenation and therapeutic plasma exchange

Vascular access connection configurations during tandem extracorporeal membrane oxygenation (ECMO) and therapeutic plasma exchange (TPE) may impact exchange kinetics. In these tandem procedures, typically the TPE inlet line is proximal to the TPE return line with respect to blood flow in the ECMO device, maximizing the opportunity for replacement fluid homogenization within the ECMO circuit. However, if TPE inlet and return line connections are switched, recirculation-a phenomenon in which replacement fluid leaving the TPE return line is prematurely drawn into the TPE inlet line prior to satisfactory homogenization within the ECMO circuit-will occur. Such recirculation could diminish TPE efficacy in patients on ECMO and mitigate therapeutic benefits. Using a mathematical model of recirculation in tandem ECMO and TPE, we demonstrate that the predicted impact of recirculation is negligible and vascular access connection positioning does not appear to be a point of clinical concern with regard to TPE kinetics.

Optimizing renal replacement therapy for patients who need extracorporeal membrane oxygenation: cross-talk between two organ support machines

Following a substantial increase in the utilization of extracorporeal membrane oxygenation (ECMO) during the last decade, its associated benefits and complications, including acute kidney injury have become more apparent. Acute kidney injury requiring dialysis during the ECMO treatment is very common and is associated with adverse outcomes. Cross talk between ECMO and dialysis equipment has been debated in the literature in order to enhance the quality of dialysis and avoid its potential adverse events.

Na et al. recently published the results of a prospective experiment by using three different methods for integration of the continuous renal replacement therapy device into the ECMO circuit. In this experiment, the investigators showed that by using three different connection strategies between continuous renal replacement therapy device and ECMO and the utilization of three separate structures of pressure control lines, the dialyzer lifespan could be optimized.

In this commentary, following a brief review of the ECMO and dialysis devices history and cross talk, we discuss the findings by Na et al. and provide additional insights for future investigations.