Electrical Safety for Active Medical Devices: The IEC 60601-1 Standard

Medical devices that have an electrical power source must meet special safety requirements. The standard IEC 60601-1 “Medical electrical equipment – Part 1: General requirements for basic safety and essential performance” describes these requirements and is therefore one of the most important and most extensive standards for medical devices. In this article we give a general overview of the structure of the basic standard IEC 60601-1.

Scope of the standard

The IEC 60601-1 standard applies to the basic safety and essential performance characteristics of medical electrical devices. The standard calls this type of medical device ME equipment or ME systems. The standard defines ME equipment as electrical (medical) devices with an applied part or as those that transfer or detect energy to or from the patient. A ME system is the combination of individual devices, at least one of which must be ME equipment. The devices are connected by a functional connection or a multiple socket.

The IEC 60601 series of standards does not apply to in vitro diagnostic devices. The IEC 61010 series of standards is used here. It also does not apply to implantable parts of active implantable medical devices to which the ISO 14708 series of standards applies, and to medical gas supply systems that are specified in the ISO 7396-1 series of standards.

Structure of the Standard

The structure of the IEC 60601 series is given by a basic standard (IEC 60601-1) that defines general requirements. The basic standard then serves as the fundament for special determinations, the so-called collateral standards. Regarding the nomenclature, the collaterals are referred to as 60601-1-X and cover general specifications for basic safety and the essential performance features for device subgroups (e.g., radiological devices) or for certain properties of all ME equipment where a further specification of the basic standard is required. In detail there are the following collaterals:

  • IEC 60601-1-1: Medical electrical equipment – Part 1-1: General requirements for safety – Collateral standard: Safety requirements for medical electrical systems
  • IEC 60601-1-2: Medical electrical equipment – Part 1-2: General requirements for basic safety and essential performance – Collateral Standard: Electromagnetic disturbances – Requirements and tests
  • IEC 60601-1-3: Medical electrical equipment – Part 1-3: General requirements for basic safety and essential performance – Collateral Standard: Radiation protection in diagnostic X-ray equipment
  • IEC 60601-1-6: Medical electrical equipment – Part 1-6: General requirements for basic safety and essential performance – Collateral standard: Usability. The standard is valid, but it has been replaced by IEC 62366.
  • IEC 60601-1-8: Medical electrical equipment – Part 1-8: General requirements for basic safety and essential performance – Collateral Standard: General requirements, tests and guidance for alarm systems in medical electrical equipment and medical electrical systems
  • IEC 60601-1-9: Medical electrical equipment – Part 1-9: General requirements for basic safety and essential performance – Collateral Standard: Requirements for environmentally conscious design
  • IEC 60601-1-10: Medical electrical equipment – Part 1-10: General requirements for basic safety and essential performance – Collateral Standard: Requirements for the development of physiologic closed-loop controllers
  • IEC 60601-1-11: Medical electrical equipment – Part 1-11: General requirements for basic safety and essential performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical systems used in the home healthcare environment
  • IEC 60601-1-12: Medical electrical equipment – Part 1-12: General requirements for basic safety and essential performance – Collateral Standard: Requirements for medical electrical equipment and medical electrical systems intended for use in the emergency medical services environment

Furthermore, the IEC 60601 series of standards includes special specifications, the so-called particular standards, which can also be viewed as product standards. As a rule, they comply with the IEC 60601-2-XY nomenclature and describe special aspects for basic safety and the essential performance characteristics of specific ME equipment.

The particulars can modify, replace or invalidate requirements of the basic standard and can also impose further requirements. Should a collateral standard also apply to the same scope for which there is also a particular standard, then the particular has priority over the collateral.

General Requirements

The basic standard sets general requirements for ME equipment and systems of which the risk management process is a central part. This is necessary for compliance with IEC 60601-1 and takes place in accordance with the relevant risk management standard ISO 14971. IEC 60601-1 explicitly refers to ISO 14971, but allows exceptions, especially with a view to production and inspections. How a risk management process is carried out in detail can be found in our article on risk management for medical devices.

In the course of the mandatory risk analysis, manufacturers must determine the “essential performance characteristics” of the clinical functions of the ME equipment or system. These describe the minimal functioning of the device so that it at least works in a way that it does not put user or patient in a situation of an unacceptable risk. The aim of the risk management process is then to use suitable methods to control any risks and to maintain the key performance characteristics.

In the course of risk assessment, risk management and risk control of a ME equipment or system, IEC 60601-1 specifically addresses certain safety-critical aspects and requires them to be taken into account. This includes the expected service life, requirements for patient-contacting parts and components, the technical suitability of the power supply and specific characteristics of the power consumption.

Another general requirement of IEC 60601-1 and part of risk management is the “single-fault-condition” of ME equipment. It is required, that no unacceptable risk occurs during the expected operating time, although a first fault has occurred. The manufacturer uses the results of the risk analysis to simulate possible errors and to check failures.

Further general requirements of IEC 60601-1 relate to representative sample tests of ME equipment. This includes specifications for the number of test items, for ambient temperature, humidity and humidity pretreatment, pressure, operating conditions, test sequences, power supply as well as for the procedure with application parts and touchable parts.

Classification, Labeling and Documents

The IEC 60601-1 standard specifies how ME equipment and systems must be classified and identified by the manufacturer in terms of protection classes. The main criteria are:

  • protection against electric shock
  • protection against harmful penetration of water or solid substances
  • sterilization process
  • suitability for use in oxygen-enriched environments
  • operating mode (continuous operation or non-continuous operation)

The corresponding labels must be usable, i.e., especially legible and permanent. The standard specifies the required information, such as information on mains voltages or current types for ME equipment connected to a supply network. There is also information on the location of a label, i.e., on the outside or inside of the device or on the operating elements and display facilities. Safety and pictorial symbols to be used, colors of the cable insulation, signal lamps and operating elements are also specified. Usually, documents must be enclosed with ME equipment, which contain at least an instruction manual and a technical description. These documents are part of a ME equipment. The essential components of the documents are specified in the standard.

Protection Against Hazards

A detailed part of the IEC 60601-1 standard deals with specifications for protection against hazards that can arise from ME equipment. The electrical current itself is a major source of danger in active medical devices, so the standard makes basic statements about protection against electrical shock. There are requirements for power sources and the limitation of voltage, current and energy. The electrical separation of components, connections, lines, etc. by means of suitable constructive measures is also part of the specifications. Further specifications concern grounding, leakage and auxiliary currents, creepage and air distances, components, line connections and the design of power supply units.

Another source of danger arises from the mechanical transfer of energy. Moving parts, surfaces, corners, edges or instabilities can lead to various mechanical hazards, such as a crush, pinch, scrape or cut. The IEC 60601-1 therefore describes a multitude of requirements with regard to gap dimensions, safety distances, protective devices, stops or positioning. There are also specifications relating to vibrations and sound energy as well as pressure vessels and carrying systems.

Excessive radiation can also lead to hazards. This applies to X-rays, alpha, beta, gamma, neutron and other corpuscular radiation, microwaves, lasers and other visible electromagnetic radiation as well as infrared and ultraviolet radiation. Definitions relate primarily to the amount of radiation and methods of determination, or corresponding performance values. At this point, reference is also made to specific standards.

Other sources of danger include excessive temperatures and the effects of fire. IEC 60601-1 specifies the maximum permissible temperatures of devices under certain conditions, such as whether there is skin contact or whether contact is likely. In general, fires or escaping flames, which can also lead to excessive temperatures, must be avoided in any case. Therefore, requirements are placed on ME equipment in oxygen-enriched environments or the fire resistance of housings, for example.

In addition, factors such as overflow, spillage, leakage, penetration of water or solid materials, cleaning, disinfection, sterilization and substance compatibility play an important role with a view to potential hazards. The same applies to the biocompatibility of ME equipment and the guarantee of an uninterrupted power (mains) supply. The standard also sees sources of danger in the case of imprecise control elements, display devices and alarm systems and refers at this point to the corresponding supplementary standards. Further stipulations concern the protection against incorrect and thus dangerous initial values, in particular with a view to exceeding limit values for diagnostic or therapeutic radiation.

Medical Software

When it comes to medical software, the IEC 60601-1 standard defines “Programmable Electrical Medical Systems”, or “PEMS”, and dedicates a separate section to this. The standard places PEMS in direct relation to the required risk management process and requires the documentation of a software life cycle. In addition, a documented requirements specification is required, a PEMS architecture derived from it and a corresponding PEMS verification and validation. The standard user must observe special requirements if he wants to integrate PEMS into an IT network that has not been validated by himself.

The originally existing supplementary standard for software, IEC 60601-1-4, has been withdrawn and replaced by IEC 62304. This standard explicitly defines requirements for the life cycle of medical device software and applies to the development and maintenance of medical software both as an independent medical device and as an integral part of such. We discuss the topic in detail in our technical article Software Life Cycle for Medical Devices.

Construction of ME Equipment and Systems

In further sections, IEC 60601-1 specifies requirements for the construction of ME equipment and systems in connection with suitable test methods and criteria.

ME equipment must have user-friendly arranged operating elements and be constructed in such a way that adequate access for maintenance purposes is guaranteed. ME equipment must demonstrate sufficient mechanical strength and meet a number of defined test criteria. Examples are shock, impact and drop resistance. In general, device components must be designed and installed in such a way that possible damage is minimized as described above.

For ME systems, IEC 60601-1 formulates special requirements with regard to accompanying documents, power supply, housing structure, isolating devices, leakage currents, protection against mechanical hazards, power supply interruptions, connections and wiring.

Electromagnetic Compatibility

Finally, IEC 60601-1 deals with the requirements for electromagnetic compatibility. As part of the obligatory risk management process, the manufacturer is asked to evaluate and take into account the electromagnetic phenomena that prevail at the place of use of a ME equipment or system. The same applies in reverse to the electromagnetic phenomena which are generated by the ME equipment or system itself and which could impair the performance of other devices or devices. Reference is made to supplementary standard IEC 60601-1-2.

Conclusion

The IEC 60601-1 basic standard, together with the collateral and particular standards, is an extremely comprehensive set of standards and mandatory reading when placing on the market active, i.e., powered medical devices including software.

The entire series of standards is subject to constant updates and adjustments simply because of its scope. Virtually all supplementary standards are currently being updated, so that corresponding draft standards are published in almost all cases. In addition, an update in the form of a 2nd amendment of IEC 60601-1 has recently been published. In addition, there have been changed regulatory requirements for medical devices that result from the MDR and that must be referenced in normative terms. At the same time, the EU has not yet harmonized all the relevant standards, including EN 60601.

We recommend to follow the current developments around the IEC 60601 series of standards carefully, as it relates to basic requirements for ME equipment and systems. Use our offers and the specialist knowledge of our experts.

Write a comment!

Your email address will not be published. Required fields are marked *