How ActivMix Technology Enhances CO2 Removal in the Hemolung RAS
By ALung Technologies, Inc.
The Hemolung Respiratory Assist System (RAS) is the only extracorporeal CO2 removal system that has been specifically designed to provide the safest, simplest and most efficient ECCO2R therapy. Other systems are non-integrated, modified ECMO or dialysis arrangements, and as such, have neither the level of safety, simplicity, nor efficiency of the Hemolung RAS. Due to its unique and proprietary gas exchange technology, the Hemolung RAS can provide removal of up to 50% of basal metabolic CO2 removal at ultralow flows, utilizing only a single, 15.5 French, veno-venous, dual-lumen catheter.
Levels of CO2 removal provided by the Hemolung RAS have been shown in studies to safely and successfully enable both avoidance of intubation in COPD patients experiencing acute exacerbations, and application of ultra-protective ventilation strategies in patients with acute lung injury and ARDS.
The “heart” of the Hemolung technology that makes possible the significant advancements in safety, efficiency, and ease of use is the unique design of the Hemolung Cartridge. The Hemolung Cartridge incorporates a hollow core pump which spins within a cylindrical bundle of hollow fiber membranes, thus integrating both a pump and gas exchanger within a single component.
The spinning core simultaneously provides three critical functions:
- Pumping of blood: Spinning of core generates centrifugal pumping of blood through the impeller channels tunneled in the upper plate of the spinning core;
- Increase of CO2 removal efficiency: Positioning of a spinning surface adjacent to the fibers generates secondary flow patterns within the blood by reducing the thickness of the fluid boundary layer that forms when the blood flows past the outer membrane surface. The reduced boundary layer thickness increases the rate of CO2 diffusion out of the blood compared to a passive flow arrangement.
- Prevention of clot formation on the membranes: The secondary flow patterns generated by the surface of the spinning core also prevent formation of clots within the membrane bundle at ultra-low circuit flows of 350-550 mL/min.
The spinning core design allows the Hemolung RAS to be the only ECCO2R system with a single component in the extracorporeal circuit. Both pumping and gas exchange are integrated in to this one component. A heat exchanger is not required because of the high CO2 removal efficiency, and hence the ultra-low flow.
Other ECCO2R systems cannot operate at such low flows without reduced rates of CO2 removal or without a higher incidence of membrane clotting. Membrane clotting requires replacement of the membrane component during therapy which not only increases cost, but also increases risk to the patient. The need for more membrane replacements increases the risk of air embolism, and re-exposes the blood to fresh membrane surface area. Each time blood is exposed to a fresh membrane surface area, more blood proteins and platelets are adsorbed to the surface, depleting their content from the blood, and hence, amplifying coagulopathy and/or complement activation.
In addition to the spinning core technology, the Hemolung RAS also utilizes proprietary membrane coating technology and sweep gas flow control. The Hemolung fibers consist of microporous membranes coated with both an ultrathin, non-porous siloxane layer and covalently bound heparin molecules which combine to prevent plasma leakage, or wetting, and to reduce thrombin formation on the membrane surfaces. Sweep gas flow through the fiber lumens is controlled with vacuum driven negative pressure that both prevents possible air embolism and automates the purging of condensation in the sweep gas pathway due to insensible water vapor diffusion from the blood across the membrane wall. Furthermore, vacuum driven sweep gas flow enables the option of using room air as the sweep gas source, which further simplifies operation.
The Hemolung RAS delivers clinically significant CO2 removal of 30% – 50% of basal metabolic production with:
- Ultra-low blood flows of 350 – 550 mL/min
- Single, 15.5 Fr, venous catheter
- Simple, user-friendly, low-maintenance operation
- Durable, long-lasting, single component circuit
- Minimization of extracorporeal therapy risks
The combination of unique technologies utilized by the Hemolung RAS delivers the safest, simplest, and most efficient low-flow ECCO2R therapy available for improving the ability to rest the lungs of patients suffering from acute hypercapnic respiratory failure.