BackgroundThere is increasing evidence demonstrating the value of partial extracorporeal CO2 removal (ECCO2R) for the treatment of hypercapnia in patients with acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. Mechanical ventilation has traditionally been used to treat hypercapnia in these patients, however, it has been well-established that aggressive ventilator settings can lead to ventilator-induced lung injury. ECCO2R removes CO2 independently of the lungs and has been used to permit lung protective ventilation to prevent ventilator-induced lung injury, prevent intubation, and aid in ventilator weaning. The Low-Flow Pittsburgh Ambulatory Lung (LF-PAL) is a low-flow ECCO2R device that integrates the fiber bundle (0.65 m2) and centrifugal pump into a compact unit to permit patient ambulation.MethodsA blood analog was used to evaluate the performance of the pump at various impeller rotation rates. In vitro CO2 removal tested under normocapnic conditions and 6-h hemolysis testing were completed using bovine blood. Computational fluid dynamics and a mass-transfer model were also used to evaluate the performance of the LF-PAL.ResultsThe integrated pump was able to generate flows up to 700 mL/min against the Hemolung 15.5 Fr dual lumen catheter. The maximum vCO2 of 105 mL/min was achieved at a blood flow rate of 700 mL/min. The therapeutic index of hemolysis was 0.080 g/(100 min). The normalized index of hemolysis was 0.158 g/(100 L).ConclusionsThe LF-PAL met pumping, CO2 removal, and hemolysis design targets and has the potential to enable ambulation while on ECCO2R.

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.

The objective of this work was to conduct pre-clinical feasibility studies to determine if a highly efficient, active-mixing, adult ECCO2R system can safely be translated to the pediatric population. The Hemolung Respiratory Assist System (RAS) was tested in-vitro and in-vivo to evaluate its performance for pediatric veno-venous applications. The Hemolung RAS operates at blood flows of 350 – 550 mL/min and utilizes an integrated pump-gas exchange cartridge with a membrane surface area of 0.59 m2 as the only component of the extracorporeal circuit. Both acute and 7-day chronic in-vivo tests were conducted in healthy juvenile sheep using a veno-venous cannulation strategy adapted to the in-vivo model. The Hemolung RAS was found to have gas exchange and pumping capabilities relevant to patients weighing 3 – 25 kg. Seven-day animal studies in juvenile sheep demonstrated that veno-venous extracorporeal support could be used safely and effectively with no significant adverse reactions related to device operation.