Researchers have created an artificial lung that uses air as a ventilating gas instead of pure oxygen - as is the case with current man-made lungs, which require heavy tanks of oxygen that limit their portability. The prototype device was built following the natural lung's design and tiny dimensions and the researchers say it has reached efficiencies akin to the genuine organ. With a volume roughly the same as a human lung, the device could be implanted into a person and even be driven by the heart.
The artificial lung is filled with breathable silicone rubber versions of the blood vessels that branch down to a diameter less than one-fourth of human hair. It was created by first building a mould with miniature features and then layering on a liquid silicone rubber that solidified into artificial capillaries and alveoli. They air and blood channels were then separated with a gas diffusion membrane.
By making the parts of the artificial lung on the same scale as the natural lung, the researchers say they were able to create a very large surface-area-to-volume ratio and shrink the distances for gas diffusion compared to the current state-of-the-art. In comparison to current artificial lung systems that require pure oxygen due to their inefficient oxygen exchange, tests of the new artificial lung using pig blood showed a three to five times improvement in oxygen exchange efficiency over current devices. It is this efficiency that enables the new artificial lung to use plain air instead of pure oxygen as the ventilating gas.
Blood is injected into the device's fluid inlet, while air is fed into the gas inlet. Oxygen molecules diffuse across the gas exchange membrane into the blood on the way to the blood outlet, while carbon dioxide in the blood fed into the device would diffuse across the membrane to be released through the air outlet.
"Based on current device performance, we estimate that a unit that could be used in humans would be about 6 inches by 6 inches by 4 inches tall, or about the volume of the human lung. In addition, the device could be driven by the heart and would not require a mechanical pump," said Joe Potkay, a research assistant professor in electrical engineering and computer science at Case Western Reserve University.
Potkay says the device is a major step towards an easily portable and implantable artificial lung and the team envisions patients using the technology while allowing their own diseased lungs to heal, or implanting one while awaiting a lung transplant.
Potkay's team, which includes Brian Cmolik, MD, an assistant clinical professor at Case Western Reserve School of Medicine, and Michael Magnetta and Abigail Vinson, biomedical engineers and third-year students at Case Western Reserve University School of Medicine, is now collaborating with researchers from Case Western Reserve's departments of biomedical engineering and chemical engineering to develop a coating to prevent clogging in the narrow artificial capillaries and on construction techniques needed to build a durable artificial lung large enough to test in rodent models of lung disease.
The Case Western Reserve University researchers expect to have human-scale artificial lungs in use in clinical trials within a decade.
