Acute respiratory distress syndrome: asymmetrical membranes to the rescue

Patients suffering from acute respiratory distress syndrome (ARDS) may need to be ventilated artificially in emergency situations. Here, medical professionals use a heart-lung machine to perform extracorporeal membrane oxygenation (ECMO) – it involves taking and enriching blood from the body with oxygen and removing carbon dioxide using a membrane oxygenator, then reintroducing the blood back into the bloodstream. While the procedure is extremely taxing on patients, a team at the Fraunhofer Institute for Applied Polymer Research IAP (Fraunhofer IAP) in Potsdam, Germany, has developed a new kind of membrane structure that allows faster gas exchange in order to make the blood oxygenation easier on patients.

Commercial membranes in blood oxygenation have a symmetrical structure and homogenous, uniform porosity, and so permit slow oxygen exchange. To intensify ventilation support, the researchers designed an asymmetrical polymer membrane structure – these are distinguished by their heterogeneous, non-uniform porosity. It has small cavities overlapping larger ones toward the separation layer, which allows for quick transport of gas by convection and diffusion.

“Our membrane possesses exceptionally high gas permeability and high mechanical stability. On top of this, the membrane material is both inert and soft, just as it ideally should be for a material that comes into contact with blood,” explains Fraunhofer IAP’s engineer Murat Tutuş.

The structure was initially implemented in flat membranes made of hollow fibres to facilitate easy and cost-effective upscaling. But, the researchers want to transform the extracorporeal blood oxygenation process into an intracorporeal one byminiaturising the membrane such that it can be placed in the aorta, which has a diameter of around one centimetre. They are currently developing a hollow-fiber spinning machine at the institute, due to be commissioned in early 2020.

Membrane morphologies can be adapted to specific requirements and their separation layers suited to other medical applications, such as dialysis or determining blood sugar levels. Industrial uses are also conceivable – for example, the hollow-fibre membranes could be adapted for water purification or as air filters.

Category: Features, Technology & Devices