Chapter 7 Chapter 7 The Evolution of Technology: Scientific Method, Engineering Design, & Translational Research In previous chapters, we learned about the epidemiology and patho- physiology of the leading causes of death throughout the world. We saw that both the causes of mortality and the availability of healthcare re- sources vary widely throughout the world. In this chapter, we will exam- ine the process of scientific discovery and how it can lead to new medi- cal technologies that benefit both individual patients and whole popula- tions. Figure 7.1 outlines the process of developing a new medical tech- nology. We begin with the science of understanding a disease. First, the etiology, or cause, of the disease must be identified. Next we examine how the disease produces symptoms, a process called pathophysiology, and how those symptoms can be detected and treated. We can use our understanding of the etiology and pathophysiology of a disease to de- sign new health care technologies to diagnose, treat or prevent the dis- ease. This process of design is referred to as bioengineering. Figure 7.1: Translational Research: the process of developing a new medical technology. 176 The Evolution of Technology New health care technologies must be tested to determine whether they are safe and effective. Generally, researchers first carry out pre-clinical trials, using cell or tissue samples or animal models, to determine whether a technology is both effective and safe. Frequently the results of these trials sug- gest ways to improve a technology before it is ready to pro- ceed to clinical trials with human subjects. New technologies which show promising pre-clinical results can proceed to clinical trials. These experiments must be carefully designed to ensure that the rights of patients are preserved. If a new technology shows promising results in clinical trials, then it can move from the research lab to general practice. Figure 7.1 illustrates a vector which originates at the lab bench and terminates at the patient's bedside. Progress in medical research depends on moving new scientific ideas forward along this vector; research designed to advance new ideas from bench to bedside is known as translational research. Although the vector is shown as a straight line, we will see that progress is usually not made in a linear manner; more frequently the vector in Figure 7.1 can be thought of as a two-way street, with new scientific ideas as well as incremental improvements in technologies often originating from clinical observations. Translational re- searchers seek to make progress along this path by ad- dressing the connections between the evolution of a new scientific idea, its translation into new technologies, the re- sultant improvements necessary to ensure their safety and efficacy, and the appropriate use of these technologies to improve health. Throughout Unit 3, we will examine the process of medical technology development in detail, using case studies cen- tered around the prevention of infectious disease (Chapter Figure 7.2: An example of a simple scientific question is: Why does ice 8), the early detection of cancer (Chapter 10), and the treat- float? ment of heart disease (Chapter 12). We begin this Unit by examining the process of technology development in detail. http://www.nationalgeographic.com/ As we examine the technology development process, we traveler/articles/ will also profile several researchers who have made impor- images/1019antarctica.jpg tant contributions to translational research. The Process of Discovery The Scientific Method: The process of scientific discovery begins with a question. Why is the sky blue? Why do leaves turn color in the fall? Why does ice float (Figure 7.2)? As we seek to better understand natural phenomena, we develop new scientific knowledge. Science is the body of knowledge about natural phenomena which is well founded and test- able. The purpose of scientific study is to discover, create, 177 Chapter 7 Steps of the scientific method Example Pose a question Why won’t my car start? Generate a hypothesis The battery is dead Design experiments to test the hypothesis Try turning on the lights in the car The lights turn on, therefore the battery is not Carry out the experiments; analyze data dead Revise the hypothesis if necessary Perhaps I am out of gas Table 7.1: The scientific method can confirm, disprove, reorganize, and disseminate statements be used to answer both simple and that accurately describe some portion of the physical, complex questions in science. chemical, or biological world. Scientists have developed a methodic approach to guide them in the search for new sci- entific knowledge. This inquiry-driven process is termed the scientific method, and it can be used to answer questions that are very basic in nature (what controls cell division?) as well as those that are more applied (why do tumor cells grow rapidly?). Often the distinction between basic and ap- plied science is blurry, and advances in basic science can rapidly and unexpectedly lead to new technologies. Table 7.1 gives an overview of the steps in the scientific method. After posing a question about a phenomenon that is not yet understood, scientists study work that has been done in this area. Based on this work they formulate a hy- pothesis to explain the phenomenon. The hypothesis repre- sents an educated guess that answers the question origi- nally posed and is consistent with observations made thus far. Formulation of the hypothesis is a critical step, because it serves as a guide for the rest of the inquiry process. You can think of a hypothesis as a mental model of how a proc- ess works. A good hypothesis will predict which variables affect a phenomenon, how these variables affect the phe- nomenon, as well as which variables are irrelevant. Using this mental model as a guide, experiments are then designed to predict how the system will respond in ways that have not yet been tested. Where possible, in these ex- periments the effects of different variables are examined one at a time. In biological research scientists often com- pare the response of two samples to different conditions. The control group and the experimental group are subject to identical conditions with one exception. Differences in the response of the two groups are attributed to the variable that was changed. The groups can be groups of cells, groups of animals, or groups of human subjects. Because of biological variability, the number of specimens in each group needs to 178 The Evolution of Technology The ABC pump’s initial introduction: June 1, 2007 Kim Malawi As a bit of background, the ABC pump is how my senior design team refers to our project. It’s a device to accurately and precisely provide doses of liquid oral medication to children. It also as- sesses compliance/adherence with an attached counting mechanism. I brought it with me to Malawi and am showing it to the doctors here (a little at a time) and asking for comments about it. Dr. Jean thinks it’s a really great idea. Her concerns are that it might not be durable enough and that patients might mess with the counting mechanism because they think they’re supposed to have used a certain number of doses. I think the durability problem will be taken care of when it’s manufactured out of plastic. And we might be able to address the compliance issue by facing the numbers of the counter into the device so that only the doctor can take it out and check it. I’ll show it around more today. 179 Chapter 7 be large enough to ensure that observed differences can be attributed to true differences in response and not just speci- men-to-specimen variability. In Chapter 13, we will examine how to choose the number of subjects in a study to ensure sta- tistically meaningful results. The results of the experiments are then analyzed to determine whether or not they are consistent with the hypothesis. If the results are not consistent, the hy- pothesis must be revised and new experiments are designed to test the revised hypothesis. Over time, if many experiments are found to be consistent with a given hypothesis then it becomes accepted as a theory or scientific law. Engineering Design: Advances in basic science can lead to inventions that improve our lives, but this is not the goal of the scientific method. Engineering is the profession that makes this connection. Thomas Tredgold defined engineering as the “art of directing the great sources of power in nature for the use and convenience of man.” Vannevar Bush carried it further, saying, “engineering. in a broad sense. is applying science in an economic manner to the needs of mankind”.[1] Engineers de- sign new products or processes in response to a particular need. Table 7.2 outlines the steps of the engineering design method. The first step is to identify a need. For example, cars that emit fewer pollutants would benefit the environment. Tools to detect cancers at their earliest stage would reduce cancer mortality. Once a need has been identified, the next step in the engineer- ing design method is to define the problem. The problem defini- tion consists of a carefully considered list of requirements that a solution must meet in order to be useful. This is sometimes re- ferred to as a design specification. The specification considers both what the product should do as well as how much the prod- Table 7.2: The engineering design uct can cost. Once the specifications have been fully devel- method applies scientific knowledge to oped, engineers gather information and use this information to design technologies that meet human needs.