By Stacy Lipson
Researchers from the Department of Veterans Affairs Medical Center and Case Western Reserve University in Cleveland have invented an artificial lung that breathes regular air instead of purified oxygen.
I spoke with Joseph Potkay, the study author whose research on the artificial lung appeared in the journal Lab on a Chip. Below is an excerpt of our conversation.
How does the artificial lung work?
The artificial lung works just like the natural lung - it adds oxygen to and removes carbon dioxide from the blood. It does this in the same way that the natural lung does as well. Inside the artificial lung, blood and air are separated by a very thin membrane. This membrane allows gas - oxygen and carbon dioxide - to freely pass through it by the process of diffusion. Due to a difference in partial pressure, oxygen flows from the air through the membrane and into blood, enriching it. For carbon dioxide, the process is reversed.
What is it made out of?
The artificial lung is made completely out of silicone rubber, otherwise known as polydimethylsiloxane or PDMS. It is formed using microfabrication and micromolding techniques.
How is this different from previous technologies?
In this work we have utilized microtechnology to produce artificial capillaries and a membrane that exhibit feature sizes that are very close to those found in the natural lung. These small features result in very small diffusion distances which result in a high gas exchange efficiency. This high efficiency has enabled us to use air to ventilate the artificial lung. Previous technologies have required pure oxygen due to their inefficiency. Thus, in essence, this technology eliminates the need for bulky pure oxygen gas cylinders and is a step towards truly portable and implantable artificial lungs.
What is it modeled after? What parts are used?
The device is designed to roughly mimic the natural lung. It contains artificial vessels, capillaries, and aveoli that are similar in size to those found in the natural lung.
How can this match a regular human lung?
There are two main areas of improvement that are needed before this technology can match the impressive human lung. First, we must scale the device up in size to be able to support larger blood flow and gas exchange rates. Second, we must improve the biocompatibility of the device so that it will have a longer lifetime when interfacing with the body. Even so, in the near term, we expect that the resulting technology will be utilized for short-term rehabilitation from lung disease or as a bridge to transplant.
Why is this artificial lung more efficient than previous technologies?
This artificial lung is more efficient than previous technologies due to its small feature sizes and, thus, small gas diffusion distances.
What tests have been done on the artificial lung?
Thus far, the gas exchange performance of the artificial lung has been tested in the laboratory using pig blood. We hope to scale up the device in size to be able to provide respiratory support to small animals in the next couple years.
What do you hope will come from your research? How will this effect lung disease in the future?
We hope that this technology will be used in portable artificial lung systems to treat patients suffering from acute and chronic lung failure. We hope it will not only save lives, but also improve the quality of life for patients requiring treatment with an artificial lung device. Due to gas exchange and size limitations, current artificial lung patients are virtually immobile.
When do you hope to have human scaled artificial lungs available to the public?
We hope to begin animal tests in a couple of years and human trials in eight to ten years.
Image: via Case Western Reserve University
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