Scientific advancement in the use of artificial lungs

Dr. Keith Cook of Carnegie Mellon University, Department of Biomedical Engineering has developed an artificial lung that promises to provide needed long term respiratory support for patients waiting for a transplant. He joins Hari Sreenivasan to discuss this scientific advancement.

TRANSCRIPT

According to the American Lung Association, more than 33 million Americans live with a chronic lung disease like asthma or emphysema.

In the most serious cases, lung transplantation can be an option, but it's risky and still requires a donor.

Dr. Keith Cook of Carnegie Mellon University's Department of Biomedical Engineering has developed an artificial lung that promises to provide needed long-term respiratory support for patients waiting for a transplant.

There's a big gap there between when somebody needs a lung and when somebody actually gets one, right?

Yeah, and there's a limited number of donor lungs.

There are only 2,000 transplants every year in the United States, and so that's a huge gap.

Most patients don't even make it onto the waiting list.

So, what do we have on the table here?

Is this an artificial lung?

So, I lead the bioengineered-organs Initiative at Carnegie Mellon University, and we work on artificial organs, as well as tissue-based organs and things that are in between.

This is a fully artificial lung.

Okay.

Would that go in someone's body?

No, these devices actually would sit on the outside of a patient.

So they would sit at belt level.

Okay.

One of the major engineering challenges we have with these devices is that they fail due to clot formation.

And the current devices fail within weeks, and we're trying to make it to the point where these devices will last for months, but we would still need to replace the organ.

Okay, when you say 'clot,' what kind of clots are happening in there?

So, anytime blood contacts an artificial surface, it immediately begins to clot.

And so, slowly, over time, these devices will start to fill up with clots, and so it blocks blood flow, it reduces the gas-exchange efficiency of the device, and so you need to use anticoagulants to slow that down, but that can create bleeding risks.

We're not just talking about two plastic boxes here.

What's inside there?

Yeah, so it's hard to see inside the device, so I brought these along.

These essentially are the artificial alveoli of the artificial lung.

So, they look just like threads, but they're really small tubes, and we can flow 100% oxygen through the inside of the tubes, and then oxygen diffuses out, and carbon dioxide diffuses into the inside of the tubes.

So, that's what the blood would actually touch?

Yeah, yeah.

And that's the challenge, is that these things are great for providing gas exchange, but they also accelerate clot formation because they're fairly densely packed.

So, does this mean every month, every few months, you'd want to change the filters?

Yeah, so we do think of this as sort of like a razor and razor-blade combination.

So all the attachments to the patient, those are the razor, and this is the blade.

And so, currently, devices fail between one to four weeks, and you just can't send a patient home if they're going to need to come back to the hospital every one to four weeks.

So we're trying to work on devices that will last for greater than three months.

What's different about this versus what's in the marketplace today?

There's been a bit of a dogma that has come about through cardiopulmonary bypass surgery.

During those surgeries, you have an oxygenator that provides the gas exchange for the patient for a period of a few hours.

And there's a certain design that they use for those devices, and those devices have been around since the 1960s.

And, unfortunately, it's followed these devices into long-term support.

And so we have sort of changed that up.

We really work hard on creating very careful blood-flow patterns inside the device so there's no areas where blood is circling around and eddying or where blood sits stagnant.

All those areas are really rapid clot-forming regions.

And the other thing is we pack these fibers much more loosely than in those devices, and what we find is that loose packing will slow clot formation down in the devices.

Is science to a point where we would build a pump and a system like this that could last a lifetime, an artificial lung that could sit inside someone's body?

Yeah, so, we work on biomaterials approaches to coding these devices, and we work on new pharmaceutical methods for slowing clot formation only within the device, not within the patient, so they don't bleed.

But even there, I think that we're probably going to be limited to a few years on these devices.

The tissue-based devices, however, should be self-regenerating, and it's possible that those devices could last an entire lifetime.

How far away are we from that?

So, these devices, we're within five years.

The tissue-based devices, I would say probably 15 to 20.

And each year, you're talking about thousands of people who are, at times, just waiting for a transplant and sometimes don't make it.

Yeah, absolutely.

I, myself, have had relatives who that's happened to.

Keith Cook of Carnegie Mellon University.

Thanks for joining us.

Thanks a lot, Hari.