Biomedical engineeringengineering. It may be defined as "The application of engineering principles and techniques to the medical field".
Most biomedical devices are either inherently safe, or have added devices and systems so that they can sense their failure and shut down into an unusable, thus very safe state. A typical, basic requirement is that no single failure should cause the therapy to become unsafe at any point during its life-cycle. See safety engineering for a discussion of the procedures used to design safe systems.
Many biomedical devices need to be sterilized. This creates a unique set of problems, since most sterilization techniques can cause damage to machinery and materials.
Most biomedical devices are completely tested. That is, every line of software is executed, or every possible setting is exercised and verified. Most devices are intentionally simplified in some way to make the testing process less expensive, yet accurate.
Regulatory issues are never far from the mind of a biomedical engineer. To satisfy regulatory issues, most biomedical systems must have documentation to show that they were managed, designed, built, tested, delivered and used using a planned, approved process. This is thought to increase the quality and safety of the therapy by reducing the likelihood that needed steps can be accidentally omitted.
Biomedical engineers operate under two basically different regulatory frameworks. These frameworks directly affect the health of citizens by affecting the development of biomedical devices. See US FDA 510(k) documentation process for the US government registry of biomedical devices.
In the US, the Food and Drug Administration adopts an adversarial position. It actively regulates individual devices and drugs, and assumes that new therapies are both unsafe and don't work until proven otherwise. This process is not known to prevent unsafe therapies. It is well-known to create a bottleneck in the development process, and the health effects of this bottleneck have been quantified by comparing approval times in the U.S. to approval times in Europe.