Until the age of sixty three, my grandfather was a heavy smoker, and was consequently diagnosed with Emphysema. My grandfather is one of the three million one hundred thousand people in the world effected by this disease. The small airways in his lungs collapsed, causing shortness in breath. He tired easy and couldn’t do any strenuous activity. He still can’t. He was told that the only way to improve his condition would be to quit smoking. With the support of our family members, he was able to survive and to thrive with his new condition.
It began with him losing a significant amount of weight. My grandfather, normally a hefty man, seemed rather thin. My grandmother, always a worrier, took him to the hospital and he was put through a series of tests called “Pulmonary Function Testing.” This included several steps, like looking through his medical history and using a spirometer. The step that helped diagnose him was the x-ray machine.
The x-ray was first used in 1895 by Wilhelm Conrad Roentgen, a German scientist who was at the time, experimenting with vacuum tubes. The most basic part of an x-ray machine is the combination of a cathode and an anode. An anode is a type of atom that has several electron orbital levels. The electrode pair is located inside a glass vacuum tube. A current is passed through the cathode, causing it to become warmer. As the heat discharges electrons, the anode attracts the electrons across the tube. When the electron reaches the anode, it knocks an electron loose from the atoms lowest orbital. When an electron from a higher orbital falls to the lower energy level, a photon is released. Since the photon dropped from a high energy level, it is an x-ray photon. The x-ray machine beams the photons toward the film. When the x-rays hit the film, they expose it just as light would. Since bone, fat, muscles and other masses absorb x-rays at different levels; the image on the film can show different structures inside the body.
After Roentgen’s initial discovery, many other engineers, specifically biomedical and chemical engineers improved the usage of x-rays by using contrast media. Contrast media is a liquid that absorbs x-rays more effectively than the surrounding tissue. In a normal x-ray picture, soft tissue doesn’t show up very clearly, but with contrast media, the difference between the masses is clearly apparent. However, that isn’t all; currently engineers are working on creating a more precise image using high contrast x-rays. Franz Pfeiffer works in the Ecole Polytechnique Fédérale de Lausanne, in Switzerland. His new technique compares typical x-ray images with shadows. This causes the x-ray machine to catch intricate interactions between the radiation and the patient’s appendages. This allows for a better contrast. This process is called “dark-field imaging” and engineers hope to develop this idea. Some hope to advance Pfeiffer’s technique to create three-dimensional CT scans in the future.
The x-ray was the part of the Pulmonary Function Testing that allowed for my grandfather’s diagnosis. Once he was diagnosed, he had to have surgery. To keep the blood flow normal throughout the procedure, the surgeon’s made use of the Cardio-Pulmonary Bypass machine, also known as the CPB. The CPB was first developed by the surgeon, John Heysham Gibbon, in the 1930s. After one of his patients died halfway through surgery, he decided to create an artificial heart and lung machine that would keep a patient alive during surgery. One problem he had to take into consideration was the scarce amount of blood exiting the machine. To stop this, he decided to make the flow continuous instead of in short pulses. To improve this design, Dr. Gibbon collaborated with Thomas Watson, a mechanical engineer from the International Business Machines Company. After several experiments, Gibbon completed his first successful surgery on a human patient with the aid of the Cardio-Pulmonary Bypass machine in 1953.
Since then, the machine has improved immensely, however the main engineering concepts remain the same. The basic components are composed: a basin for oxygen, an oxygenator, a temperature monitor device, a pump to drive the blood back to the body, connective tubing to tie the components together, and a filter to prevent embolisms or the obstruction of arteries.
During my grandfather’s surgery, the Cardio-Pulmonary Bypass machine was integral in keeping him alive. The machine went through several stages to ensure that my grandfather’s blood flow would remain consistent. First, the surgeon inserts tubes called the venous cannulas into large blood vessels leading to the heart. The blood is then redirected to avoid the heart entirely. Engineers designed the venous cannulas so a controlled amount of blood will flow into the machine. They did this by creating tubes in different sizes and resistances. According to Bernoulli’s principles, the larger a tube is, the more liquid can flow through it for a given time. Conversely, if a tube has a greater resistance, then less fluid may pass through it. By adjusting these two properties, an engineer can create venous cannulas that allow specific rates of blood to flow from the body and into the machine’s reservoir.
When the blood leaves the venous reservoir, it travels into the pump which uses centrifugal force to coerce the blood flow. A plastic wheel in the centrifugal pump rotates quickly, propelling the blood into the heat exchanger, which lowers the patient’s internal temperature. This is done because it creates the maximum amount of oxygen the patient’s blood cells can carry. Thermal energy is transferred between the water and tubing as the blood flows through the tubes. From the heat exchanger, the cooled blood enters the oxygenator, where the blood is instilled with oxygen. The oxygenator tries to imitate the lung itself. At this point, the blood has been cooled and oxygenated, so it is ready to return to the patient’s body. However, it must pass through a filter which allows for the elimination of embolisms, which as mentioned before, is the obstruction of arteries. The filter in the machine is made of nylon or polyester thread woven into a screen with small pores. Afterwards, the blood travels through plastic tubes that lead back to the arteries. Blood then leaves the last component of the Cardio-Pulmonary Bypass machine, enters the patient, and again makes its normal journey through the circulatory system.
Recently, biomedical engineers have made major breakthroughs concerning the Cardio-Pulmonary Bypass machine. In 2007, the Lifebridge B2T was made. It is a smaller and lighter machine that weighs only 38.6 pounds. This machine is powered by a rechargeable battery, allowing it to be portable. This is helpful as the same machine can be moved around easily within a hospital, if in case it is needed during an emergency. Another new development is that of the MiniHLM, a Cardio-Pulmonary Bypass machine made for children. This machine was specifically created to be miniature, so newborns can be treated. In the future, engineers hope to create more efficient CPB machines that act just as the circulatory system of the human body would, for example, by creating an electric surface. This would need the collaboration of biomedical engineers and electrical engineers.
To this day, my grandfather, at the age of eighty two, lives a healthy life as a survivor of Emphysema. My family members praise the surgeons that successfully completed his operation; they believe that the improvement in medicinal technologies allowed him to survive. While this may be true, behind the exterior, it is the machines that surgeons used that helped diagnose him and keep him alive through surgery.
As a result, not many people understand the following fact: Engineers saved my grandfather’s life.
-"Health Guide." Emphysema. New York Times, 2013. Web. 28 Feb. 2013.
-Netting, Ruth. "X-rays." X-Rays. NASA, 27 Mar. 2007. Web. 28 Feb. 2013.
-Harris, Tom. "How X-rays Work" Howstuffworks.com, 26 March 2002. Web. 28 February 2013.
-Heisler, Jennifer. "Overview of the Cardiopulmonary Bypass Machine Used for Surgery."About.com Surgery. N.p., 22 Jan. 2012. Web. 28 Feb. 2013.
-Woodburn, Julie. "Illumin - Engineering the Heart-Lung Machine." Illumin - Engineering the Heart-Lung Machine. University of Southern California, 28 Feb. 2013. Web. 28 Feb. 2013.
-Bourzac, Katherine. "Mozilla's Mobile Firefox OS Raises Security Questions." MIT Technology Review. N.p., 22 Apr. 2008. Web. 28 Feb. 2013.
For a chance to win up to $500, imagine how engineering can help your community. Then write a plea to your city or county council to make the case for an infrastructure improvement.
Also, don't forget to look for our EngineerGirl booth at Invent It. Build It.(IIBI) IIBI is a hands-on engineering experience for girls in grades 6-12, and their families. Join 10,000 women engineers from around the globe in Austin, TX on Saturday, October 28th to prove that girls can be engineers!
Learn more and register.