An extracorporeal carbon dioxide removal (ECCO2R) device operating at hemodialysis blood flow rates

Abstract

BackgroundExtracorporeal carbon dioxide removal (ECCO2R) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCO2R device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry.MethodsA carbon dioxide (CO2) removal device was fabricated with rotating impellers inside an annular hollow fiber membrane bundle to disrupt blood flow patterns and enhance gas exchange. In vitro gas exchange and hemolysis testing was conducted at hemodialysis blood flows (250 mL/min).ResultsIn vitro carbon dioxide removal rates up to 75 mL/min were achieved in blood at normocapnia (pCO2 = 45 mmHg). In vitro hemolysis (including cannula and blood pump) was comparable to a Medtronic Minimax oxygenator control loop using a time-of-therapy normalized index of hemolysis (0.19 ± 0.04 g/100 min versus 0.12 ± 0.01 g/100 min, p = 0.169).ConclusionsIn vitro performance suggests a new ultra-low-flow extracorporeal CO2 removal device could be utilized for safe and effective CO2 removal at hemodialysis flow rates using simplified and minimally invasive connection strategies.

A mock circulation loop to test extracorporeal CO2 elimination setups

“…Similar to our approach, de Villiers Hugo et al have created a dual mock to investigate a low-flow system with a modified dialysis unit [8]. Unlike most of the described mocks, our construction allows to measure continuously [1,10,13]. Using N 2 and CO 2 as sweep gases on the primary circuit, a constant venous milieu with a p v CO 2 of 45 ± 5 mmHg can be established throughout the whole measurement series.…”

“…Extracorporeal carbon dioxide elimination (ECCO 2 R) is a method to counteract hypercapnic respiratory failure, e.g., in severe acute respiratory distress syndrome (ARDS). Furthermore, ECCO 2 R may be used in the management of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) or patients waiting for lung transplant [ 1 , 2 ]. As mechanical ventilation in ARDS therapy can lead to ventilator-induced lung injury, ECCO 2 R can be used to enable ultra-protective ventilation in patients without life-threatening hypoxemia [ 3 – 6 ].…”

“…Today, effective ECCO 2 R therapy requires blood flow rates of more than 1 L/min and consequently cannulation with relatively large cannulas [ 1 , 3 ]. Moreover, pure oxygen is frequently used as sweep gas in ECCO 2 R therapy, in order to create a diffusion gradient for CO 2 to be cleared from the blood [ 4 ].…”

Lungenersatzverfahren

“…Als weiteres Verfahren existieren Low-Flow-Systeme, bei denen Gasaustauschfilter in einen venovenösen Dialysekreislauf integriert werden. Hierbei sind allerdings lediglich Blutfüsse um etwa 300 -500 ml/min zu generieren, sodass die CO 2 -Eliminationskapazität mit etwa 30 % deutlich limitiert ist [12] und höhere Blutflüsse von etwa 1000 ml/min angestrebt werden sollten, um eine suffiziente Eliminationsrate von etwa 60 % zu erzielen [13]. Damit sind die Low-Flow-Systeme nur sehr limitierten klinischen Fragestellungen vorbehalten.…”

Estimation Methods for Viscosity, Flow Rate and Pressure from Pump-Motor Assembly Parameters

“…Patients that undergo positive-pressure mechanical ventilation for extended periods of time often develop ventilator-induced lung injuries (VILI) and acute respiratory distress syndrome (ARDS) [1] which can lead to worse quality of life and even death. Usually, extracorporeal carbon dioxide removal (ECCO 2 R) [2] devices are combined with protective ventilation strategies to let the lungs recover. However, ECCO 2 R is a highly invasive procedure that is associated with elevated risks of infection, thrombosis and-due to the high priming volumes-high load on the heart [3].…”