Biomedical Engineering Defined Pt 10

Why the change in infectious diseases? Why did I focus on that one?

What makes it so much better to be alive now in terms of your likelihood to die of an infectious disease than it did in London in 1665? Yes, but what specifically? Drugs like antibiotics, penicillin, erythromycin, again something else you probably all had experience with and you think well that’s not Biomedical Engineering, that’s science, that’s somebody discovering a molecule that kills microorganisms.

That’s true, it is science, but in order for that to go from being a science that works in a laboratory or in one hospital to being penicillin, which could be used all over the world, you’ve got to be able to make it in tremendously large quantities and that’s the work of biomedical engineers, making penicillin in the kinds of quantities that you need so that a dose could be available for everyone in the world if they got infected and to make it not just in abundance but make it cheaply enough that everyone could afford it. So, if you can make 100 tons of the drugs, but it costs $100,000 a gram that might not be a useful drug because nobody could afford to use it.

So, it’s the work of biomedical engineers, really, to take these innovations in science like drugs and make them useful, make them so that everybody can take advantage of it. And you also mentioned vaccines and we’re going to talk a lot in the middle part of the course about vaccines and the engineering of immunity. How do you engineer, what happens in our immune system in order to protect us from diseases? That’s another of an area where biomedical engineers have made tremendous contributions.

So, just to go a little bit further with that point, if you looked at the causes of death of London in 1665, here’s a list that I got from a source that was written at that time, and I don’t even understand what some of these things are, but the ones in green are infectious diseases, they’re infectious causes of disease.

Spotted fever in purples for example, which we call measles, was a significant cause of death as was the plague, which we don’t have any more, thank goodness. But, people died typically of either infectious diseases or they died during childbirth or they might have died at old age which would have been 50 or so at that time.

Biomedical Engineering Defined  Pt 10

Biomedical Engineering Defined Pt 9

Things like electricity, having electricity delivered to your home, so you had to have ways to generate electricity and to carry it from point to point and it was engineers that did that, built bridges and roads and automobiles, so we can get from one place to another relatively quickly because of that, because there are airplanes that were also developed by engineers in that century.

We designed a lot of new materials that could be used to build things that couldn’t have been done otherwise. Things like steel and polymers, or plastic and ceramics and, of course, computers which has progressed remarkably due to the work of engineers in your lifetime, until now you can carry around a cell phone, which would have been unthinkable even 30 years ago. Engineers in the twentieth century have transformed our society.

One of the other things that happened during the twentieth century is that human life expectancy increased dramatically, people started living a lot longer. So, what I plot on this graph here is as a function of time, years, dates, life expectancy as a function of time. What you’ll see here is that about for the period before sort of 1700 or so, human life expectancy was less than 40 years of age, so that means a person that was born in that year could expect to live on average about 40 years. That was the expected life span. And the expected life spans increased dramatically in the last couple of hundred years until now, or people that were born when you were born you can expect to live to be 80 years old, a doubling in life span, fairly dramatic.

So, what’s responsible for that? Why are people living longer than they did just a few hundred years ago? Well, there’s a clue here on the slide. I indicated a couple of points here where if we looked in the 1665 in London, you could ask the question, another way to ask the question why are people living so long is to ask the question, why do people die? In 1665, 93% of the people that died in that year died of infectious diseases. In contrast, if you look at a U.S. city, ten years ago in 1997 for example, then people still died but they didn’t die predominantly from infectious diseases. They died from other things, only four percent died from infectious diseases. So, one of the reasons there is a huge increase in life span is because people aren’t dying of things that they would have in prior years.

Biomedical Engineering Defined  Pt 9

Biomedical Engineering Defined Pt 8

Many of the things I showed you were things that were built from parts, that’s a good description. What makes it different from science? Science can be hands-on, you might be down at the lake picking up algae and studying them or something that would be hands-on. But what’s different, what would make you an engineer? Yeah? You design. Scientists observe and try to describe and engineers try to design.

They take those descriptions and the scientist that is known and they try to design new things, and so if you look at a dictionary, it has words like this that you’re doing designing things or another way to say that is that you’re trying to apply science, you’re looking at applications. We’re trying to take scientific information and make something new. The other thing about it is that you could make lots of things that are new but generally you think of engineers as making things that are not just new but they’re useful, that they do something that needs to be done and they do something that improves life, the quality of life of people.

So, here is a brief and very biased history of engineering. It’s short. Engineering became a discipline in about the middle of the 1800s. Lots of universities started teaching engineering as a discipline including Yale. In 1852, around that time, this might have been the first course that was offered in engineering in the country. It was taught at Yale in civil engineering in 1852 and even Yale students don’t know this. What a long distinguished history of engineering that their own institution has. In fact, the first PhD degree in engineering was awarded to a fellow named J. Willard Gibbs at Yale in 1863 for a thesis he did on how gears work or something, I forgot exactly what the details are, but have you heard of Gibbs? Is it a name that rings a bell? Where did you hear about Gibbs from? Yeah, G, Gibbs free energy, that annoying concept that you had to try to master in chemistry at some point, but Gibbs is really the father of modern physical chemistry and was one of the most famous scientists of the nineteenth century and got the first PhD in engineering here at Yale.

Then from these beginnings, engineers transformed life in the twentieth century. So, a lot of things started in the twentieth century and became common place.

Biomedical Engineering Defined  Pt 8

Biomedical Engineering Defined Pt 7

Because you trust biomedical engineers to have done a good job in designing these things and we’ll talk about how biomaterials are designed and tested and what makes a material, the properties of a material that you could use as a contact lens, what are the properties that it needs to have.

This is an example of an artificial hip. We’ve learned a lot about the mechanics of how humans work as organisms over the last 100 years or so, how we work as a sort of physical objects that have to obey the laws of physics that you know about. We live in a gravitational field and that it affects our day to day life, and if you have hip pain or a hip that’s diseased in some way, and you can’t stand up against that gravitational field in the same way, that severely limits what you can do in the world.

So, biomedical engineers have been working for many years on how to design replacement parts for joints like the hip. The artificial hip is the most well developed of those. We’ll talk about this in some detail. You can imagine that there are many requirements that a device like this has to meet in order for it to be a good artificial hip and we’ll talk about those and how the design of these has changed over the years and what we can expect in the future.

Lastly, up here, is a picture of a much smaller device. This is actually an artificial heart valve that is made of plastics and metal and can replace the valve inside your heart. Valvular disease is not uncommon in the world. We’ll talk about that a little bit. We’ll talk about how your normal valves function inside your heart and how your heart couldn’t work in the way that it did if it didn’t have valves that were doing a very complex operation many, many times a day. And then we’ll talk about how you can build something to replace a complicated small part in the body like that.

 

Well, let’s take a step back for a minute, that’s one way of looking at Biomedical Engineering by looking at sort of the things that you now about that have been the result of the work of biomedical engineers and talk more generally. But, what is engineering? What do engineers do? What makes engineering different than other fields of study? What makes it unique so that we have a school of engineering at Yale that’s separate from science and the humanities? Any thoughts? Yeah? It’s much more hands-on. You’re actually in there doing things.

Biomedical Engineering Defined  Pt 7

Biomedical Engineering Defined Pt 6

For example, you all know that the only treatment for some diseases is to get an organ transplant: a kidney transplant or a liver transplant is the only life extending intervention that can be done for some kinds of diseases.

Transplants require donors, and the donor organ is usually not at the same physical location that the recipient is, and so jets like this one have become very important in connecting donors to recipients. A team of surgeons is working to harvest an organ at one site while another team of surgeons is working to prepare the recipient at another site, and the organ is flown there.

Now, why does that happen? Because you have to get the organ from one place to another fast, right? The organ has to get from one place to another very rapidly and this is the fastest way to do it. Well, what if we could develop ways using engineering techniques to extend the life of an organ, so it didn’t have to get it where it went so quickly? Then that would open up lots of more possibilities for organ transplantation than are known now. What if we could figure out ways to avoid organ transplantation entirely? What if we could just take a few cells from that donor organ, ship them to the site, grow a new organ at the site and then implant it there? These are examples of Biomedical Engineering of the future that expand on what we currently use, which involves to no small extent, technology like this.

I would guess that probably 30% to 50% of you do this every day. You put a piece of plastic, a synthetic piece of plastic into your eye to improve your vision. Contact lens technology has changed dramatically from the time that I was born to the time that you were born, and the contact lenses you use today are much different than the ones that would have been used 30 years ago. This is Biomedical Engineering as well. Engineers who are developing new materials, materials that can be, if you think about it, there’s not very many things that you would want to put in your eye and that you would feel comfortable putting into your eye, so this is a very safe, a very inert material. What gives it those properties? What makes it so safe that it can be put in one of the most sensitive places in your body, in contact with your eyes? Why do you have confidence putting it in contact with one of the most important organs of your body?

Biomedical Engineering Defined  Pt 6