Concept Design of Lectures at Higher Education Level for Training Students of Medical Engineering

CONTENTS

Introduction

Safety in Medical Engineering

Aims of the Course

Legal Regulations

Tasks of a Medical Engineer

Mechanical Safety

Electrical Safety

Current, Voltage, Resistance

Resistances in the Human Body

Effects of Electricity on the Human Body

Electrical Safety Precautions

Power Supply Systems

IEC Protection Classes

Classification of Locations Used for Medical Purposes

Currents and Leakage Currents in Medical Engineering

Electrical Safety Measurements

Safety-Related Controls

Conclusion

List of References

INTRODUCTION

This concept is intended to help develop a course of lectures specially aimed at training medical engineering students within the scope of Engineering or Bachelor studies at an institute of higher education.

It should contain and illustrate basic aspects regarding the content of a course of lectures with its emphasis on “Safety in Medical Engineering”.

This instructional concept should also provide information and procedural instructions on drafting a lecture or lecture manuscript.

SAFETY IN MEDICAL ENGINEERING

The term “safety” in medical engineering encompasses numerous, closely linked specialist fields. Safety in medical engineering includes electrical safety, mechanical safety and also chemical and hygienic safety, as well as the safety of medical devices and equipment themselves.

This concept is particularly concerned with the electrical safety of medical devices and medical equipment. The aspect of mechanical safety can be addressed and elaborated on in other lecture courses such as “Materials” or “The use of plastics in medicine”.

The subject of chemical and hygienic safety can be addressed and elaborated on in lecture courses related to “Microbiology” and “Chemistry”. The aspect of safety within medical engineering is a component part of studies for students of medical engineering and, therefore, should be provided in a series of lectures which have been specifically organized, in didactic terms, for the topic.

Parallel to the lectures, laboratory schedules should be drawn up during which the theory conveyed in lectures can be underlined by practical, in-depth experience using real medical devices.

AIMS OF THE COURSE

The lecture course concerning “Safety in Medical Engineering” should have the following objectives and convey them. The course should explain to students of medical engineering how to handle and use medical devices and equipment in a responsible way. When doing so, it is important to include subjects involving the special requirements defined for the development and construction of medical apparatus. Medical engineering students must be made aware of the particular risks which specific medical devices represent and how to prevent these risks by being provided with practical examples.

Medical engineering students must be taught how to apply basic legal requirements, specific directives and standards and have the various explanations linked to case studies and real incidents.

After having successfully completed the “Safety in Medical Engineering” lecture course, the students should be capable of assessing practice-related examples with and on medical apparatus. Students should also be able to develop and implement approaches to solutions to prevent safety-related sources of errors.

MAIN LEGAL REGULATIONS

Since the safety of medical devices encompasses many bordering fields of expertise, only the basic legal regulations, directives and standards should (and can) be addressed during the course of lectures. The most important legal regulations applicable to everyday contact with medical devices are the following:

- Medical Devices Act (MPG) [1]

Current version dated 21th July 2014 (BGBl. I S. 1133). The purpose of this act is to regulate the trafficking of medical devices and, as a result, to ensure the safety, suitability and performance of medical device as well as to ensure the health of patients, users and third-parties is maintained and provide them with the necessary protection.

- Medical Devices Operator Ordinance (MPBetreibV) [2]

Current version dated 29th July 2009 (BGBl. I S. 2326). This directive applies to the installation, operation, usage and maintenance of medical products in accordance with § 3 of the Medical Devices Act with the exception of medical products for clinical tests or performance evaluation tests.

- DIN EN 60601-1; VDE 0750-1:2013-12 [3]

Medical electrical equipment – Part 1: General requirements for basic safety and essential performance (IEC 60601-1:2005)

- DIN EN 62353; VDE 0751-1:2012-07 [4]

Medical electrical equipment- Recurrent test and test after repair of medical electrical equipment (IEC62353:2007

- DIN VDE 0701-0702; VDE 0701-0702:2008-06 [5]

Inspection after repair, modification of electrical appliances – Periodic inspection of electrical appliances General requirements for electrical safety Edition: 2008-06, Standard

- DIN VDE 0100-710;2012-10 [6]

Erection of low-voltage installations– Requirements for special installations or locations- Part710: Medical locations- (IEC 60364-7-710:2002, modified) HD 60364-7-710:2012

- BGV A3 [7]

Accident prevention regulations / Procedural instructions

Electrical installations and equipment

Edition: 2005-01

This list of the most important basic legal texts, documents and standards does not claim to be complete. However, it does represent a minimal requirement within the development of a concept for a course of lectures concerning “Safety in Medical Engineering”.

TASKS OF A MEDICAL ENGINEER

To begin the course, the students should be introduced to a detailed description of the occupational tasks for which a medical engineer is responsible. Three professional fields must be presented, accompanied by practical examples:

- Medical engineers involved in development
- Medical engineers involved in sales
- Medical engineers involved in service.

Medical engineers involved in the development of medical devices and equipment must place the emphasis of their studies on the construction and design aspects. Proposes lecture courses will be offered and, in addition, important compulsory and optional subjects will be available.

Medical engineers involved in the sale of medical devices and equipment must place the emphasis of their studies on the business and commercial aspects. In this case, students must participate in inter-departmental lectures with an economic and business content.

Medical engineers involved in customer and technical service in respect of medical devices and equipment must place a great emphasis on the safety-related aspects when considering their professional orientation. Service technicians must be well-familiar with both the electrical and mechanical safety of medical equipment.

A major objective of a lecture course concerning “Safety in Medical Engineering” should also be to encourage students to disclose their particular preferences and skills (development, sales, service) and to provide assistance and support in selecting the right occupational field.

MECHANICAL SAFETY

The aspect of mechanical safety should represent about a quarter of the envisaged course time as compared to the aspect of electrical safety. In the case of mechanical safety of medical devices, materials science and the basics of construction technology play a major role. Therefore, a basic condition should be that the students have visited these lectures before participating in the course on “Safety in Medical Engineering”. When dealing with the topic of mechanical safety, practical examples on devices should be included in the lecture course.

Key topics which should be expanded on within a course of lectures include: aging of plastics, fatigue fractures, selecting the correct/incorrect production materials, disinfecting materials, ergonomic design of devices and operating errors.

ELECTRICAL SAFETY

The electrical safety of medical devices and medical installations should represent about a quarter of the envisaged course time for “Safety in Medical Engineering”. A basic condition for participating in this part of the lecture course is students’ familiarity with electrotechnical and physical principles and their having visited the relevant lectures beforehand. Since 90% of medical devices and equipment are powered by electricity, it is absolutely essential to expand on the principles of electrotechnology within the “Safety in Medical Engineering” lecture course.

CURRENT, VOLTAGE, RESISTANCE

Elaboration of these terms during the lecture course is a basic requirement for understanding the sources of risks of electricity in the actual medical devices and during their use, i.e. both to operators and patients. The lectures should provide a brief but detailed explanation of the origin and creation of an electric current. The difference between direct current and alternating current should be clarified and illustrated by practical examples.

The term “voltage” should be handled in the same way. Important terms which need to be expanded on include: AC voltage, DC voltage, direct current, alternating current, frequency, phases, actual values, crest factor. The term “resistance” has a particularly important significance in the field of safety of medical equipment. The lectures should emphasise the difference between pure ohmic resistance and general impedances. Since the human body does not behave like a pure ohmic resistor, it must be considered according to its specific resistance values when dealing with electrical safety in respect of the use of medical equipment; and parallels or differences to pure electrotechnology or ohmic, capacitive and inductive resistances must be explained.

RESISTANCES IN THE HUMAN BODY

In order to expand on the resistance values within the human body, an insight must be provided with regard to establishing the values as well as drawing up and producing resistance tables. Help here takes the form of the initial attempts to establish resistance values from animals (pigs, dogs, sheeps). The transfer and conversion of these experimentally established values to the human body and its peculiarities represents the educational objective. Key topics for elaboration in respect of these resistance values and emphasising the special features of the skin or organ resistance include the structure of human tissue, skin characteristics, current frequency, transition resistance, exposure time, age and constitution of the person.

In order to elucidate the flow of current through the human body or specific bodily impedances, it is helpful to complete a harmless experiment on oneself using a 9 V battery and/or a bell transformer. The students can then discover the various type-related transition resistances on the human body using simple means. In addition, this resource (voltage source, current flow and body resistance) can also be used to recapitulate the Ohm’s Law and illustrate it according to a practical example.

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