Biomedical engineering

Disciplines within Biomedical Engineering

Clinical engineering

Clinical engineering is a branch of biomedical engineering for professionals responsible for the management of medical equipment in a hospital. The tasks of a clinical engineer are typically the acquisition and management of medical device inventory, supervising biomedical engineering technicians (BMETs), ensuring that safety and regulatory issues are taken into consideration and serving as a technological consultant for any issues in a hospital where medical devices are concerned. Clinical engineers work closely with the IT department and medical physicists.

A typical biomedical engineering department does the corrective and preventive maintenance on the medical devices used by the hospital, except for those covered by a warantee or maintenance agreement with an external company. All newly acquired equipment is also fully 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. 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 medical 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.

Medical devices

A medical device is intended for use in:

• the diagnosis of disease or other conditions, or
• in the cure, mitigation, treatment, or prevention of disease,
• intended to affect the structure or any function of the body of man or other animals, and which does not achieve any of its primary intended purposes through chemical action and which is not dependent upon being metabolized for the achievement of any of its primary intended purposes.

Some examples include pacemakers, infusion pumps, the heart-lung machine, dialysis machines, artificial organs, implants, artificial limbs, corrective lenses, cochlear implants, ocular prosthetics, facial prosthetics, somato prosthetics, and dental implants.

Medical devices can be regulated and classified (in the US) as shown below:

1. Class I devices present minimal potential for harm to the user and are often simpler in design than Class II or Class III devices. Devices in this category include tongue depressors, bedpans, elastic bandages, examination gloves, and hand-held surgical instruments and other similar types of common equipment.
2. Class II devices are subject to special controls in addition to the general controls of Class I devices. Special controls may include special labelling requirements, mandatory performance standards, and post market surveillance. Devices in this class are typically non-invasive and include x-ray machines, PACS, powered wheelchairs, infusion pumps, and surgical drapes.
3. Class III devices require premarket approval, a scientific review to ensure the device's safety and effectiveness, in addition to the general controls of Class I. Examples include replacement heart valves, silicone gel-filled breast implants, implanted cerebellar simulators, implantable pacemaker pulse generators and endosseous (intra-bone) implants.

Medical Imaging

Imaging technologies are often essential to medical diagnosis, and are typically the most complex equipment found in a hospital including:

• Fluoroscopy
• Magnetic resonance imaging (MRI)
• Nuclear Medicine
• Positron Emission Tomography (PET) PET scansPET-CT scans
• Projection Radiography such as X-rays and CT scans
• Tomography
• Ultrasound
• Electron Microscopy

Tissue engineering

One of the goals of tissue engineering is to create artificial organs for patients that need organ transplants. Biomedical engineers are currently researching methods of creating such organs. In one case bladders have been grown in lab and transplanted successfully into patients[1]. Bioartificial organs, which utilize both synthetic and biological components, are also a focus area in research, such as with hepatic assist devices that utilize liver cells within an artificial bioreactor construct[2].

Regulatory Issues

Regulatory issues are never far from the mind of a biomedical engineer. To satisfy safety regulations, most biomedical systems must have documentation to show that they were managed, designed, built, tested, delivered, and used according to a planned, approved process. This is thought to increase the quality and safety of diagnostics and therapies by reducing the likelihood that needed steps can be accidentally omitted again.

In the United States, biomedical engineers may operate under two different regulatory frameworks. Clinical devices and technologies are generally governed by the Food and Drug Administration (FDA) in a similar fashion to pharmaceuticals. Biomedical engineers may also develop devices and technologies for consumer use, such as physical therapy devices, which may be governed by the Consumer Product Safety Commission. See US FDA 510(k) documentation process for the US government registry of biomedical devices.

Other countries typically have their own mechanisms for regulation. In Europe, for example, the actual decision about whether a device is suitable is made by the prescribing doctor, and the regulations are to assure that the device operates as expected. Thus in Europe, the governments license certifying agencies, which are for-profit. Technical committees of leading engineers write recommendations which incorporate public comments and are adopted as regulations by the European Union. These recommendations vary by the type of device, and specify tests for safety and efficacy. Once a prototype has passed the tests at a certification lab, and that model is being constructed under the control of a certified quality system, the device is entitled to bear a CE mark, indicating that the device is believed to be safe and reliable when used as directed.

The different regulatory arrangements sometimes result in technologies being developed first for either the U.S. or in Europe depending on the more favourable form of regulation. Most safety-certification systems give equivalent results when applied diligently. Frequently, once one such system is satisfied, satisfying the other requires only paperwork.

Training

Biomedical engineers combine sound knowledge of engineering and biological science, and therefore tend to have a bachelors of science and advanced degrees from major universities, who are now improving their biomedical engineering curriculum because interest in the field is increasing. Many colleges of engineering now have a biomedical engineering program or department from the undergraduate to the doctoral level. Traditionally, biomedical engineering has been an interdisciplinary field to specialize in after completing an undergraduate degree in a more traditional discipline of engineering or science, the reason for this being the requirement for biomedical engineers to be equally knowledgeable in engineering and the biological sciences. However, undergraduate programs of study combining these two fields of knowledge are becoming more widespread. As such, many students also pursue an undergraduate degree in biomedical engineering as a foundation for a continuing education in medical school.

Though the number of biomedical engineers is currently low (under 10,000), the number is expected to rise as modern medicine improves. Currently, according to U.S. News & World Report, the program at Johns Hopkins University is ranked first among American universities in the category of bioengineering/biomedical engineering. At the undergraduate level, an increasing number of programs are also becoming recognized by ABET as accredited bioengineering/biomedical engineering programs in the United States. Duke University, ranked second in the U.S. by U.S. News, was the first program accredited by the Engineering Council for Profession Development (now ABET) in September of 1972.

Subdivisions and Departments

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• School:Engineering
• School:Medicine
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