Medical devices essential requirements

ISO 62366 2007 Medical devices - Application of usability engineering to medical devices [12] is a design and development standard which is harmonised with medical device compliance requirements in many territories. It is closely aligned to risk management standard ISO 14971 2012, essentially ISO 62366 explores in greater depth those hazards which arise from a product s usabifity characteristics. Whilst intended as a standard to support the manufacture of medical devices it contains a useful framework that could be utilised by manufacturers of general HIT products where the user interface is associated with a number of important safety related hazards. 

Figure 9.1 Summary of key elements of the Essential Requirements from the medical device directives 90/385/EEC, 93/ 42/EEC and 98/79/EC.

The Commission provides a list of over 230 standards that may be used to establish conformance with the essential requirements of the medical device directives. 

In order to be successful as part of a medical device a polymer has to resist both biological rejection by the patient s body and degradation. The human body is an enviromnent which is simultaneously hostile and sensitive, so that materials for application in medicine must be carefully selected. The essential requirement is that these materials are biocompafible with the particular part of the body in which they are placed. The extent to which polymers fulfil this requirement of biocompafibility depends partly on the properties of the polymer and partly on the location in which they are expected to perform. For example the requirements for blood biocompafibility are stringent since blood coagulation may be triggered by a variety of materials. By contrast, the requirements for materials to be used in replacement joints in orthopaedic surgery are less severe and materials as diverse as poly (methyl methacrylate) and stainless steel can be used with minimal adverse reaction from the body. 

Where there is a dosing device provided with the product, the dose reproducibility and accuracy should be demonstrated. Examples include dropper devices, dose-measuring devices, and pen injectors. The instructions for use should also be discussed for such devices and may be particularly important for devices such as two-chamber cartridges and the like containing suspension products. It might be necessary to discuss how dosing devices meet the relevant Essential Requirements of the Medical Device Directives with reference to appropriate and relevant harmonized and other European (EN) and International Standards Organization (ISO) standards. 

A manufacturer must apply an appropriate conformity assessment procedure to their device in order to ensure that it complies with the essential requirements, after which they must certify this fact by completing a declaration of conformity. There is usually a choice of conformity assessment procedures open to a manufacturer, depending on a risk-based classification of the class into which the device falls. The two main approaches to conformity assessment are based either on an approved total quality management system audited to ISO 9000 series standard, as customised for medical devices with EN 46 000 series standard, or individual product assessment. 

Depending on the class of the device, a manufacturer may be able to choose between a number of alternative conformity assessment procedures in the assessment of whether a medical device conforms to the essential requirements. Although the rules should be considered in detail in each case, the basic options might be summarised as follows ... 

Since 1998, all medical devices marketed in Europe (EEA) must bear the CE mark, which signifies conformity to the essential requirements of the MDD. The MDD harmonized the European requirements along with device certification and the inspection procedures for manufacturers to ensure the highest degree of safety and product quality of the medical devices throughout the EC. Most important was the requirement for a full quality assurance system (Annex II of the MDD, 93/42/EEC), which included design controls for new medical device products. This was in line with the ISO 9000 series of standards established for quality systems by the International Organization for Standardization. 

The guarantee of conformity to the essential requirements of the MDD is provided by the interaction between the manufacturer and a third party, the notified body. The notified bodies are organizations that are recognized by the member states to conduct device evaluations and inspections of the quality systems of the various manufacturers. The manufacturers are held responsible for the quality, safety, and effectiveness of their medical devices. This is enforced through the manufacturer s written declaration of conformity and commitment to keep all technical information available for inspection by the notified bodies and national authorities. 

Revision of medical device regulations has occurred in other countries, including Canada and the United States, because of the European experience. In 1998, Canada changed its device regulations to include a risk-based classification system and 11 principles of safety and effectiveness, which were patterned after the essential requirements of the European MDD (22). 

Apps which are designed for healthcare professionals are essentially extensions of traditional Electronic Health Records (EHRs) but often with narrowed or very specific functionality. These can be considered clinical management systems or medical devices depending on the intended purpose. From a patient safety perspective, risk management is required in exactly the same way as for conventional health information systems if they are able in some way to adversely impact care. 

At this point it is worth mentioning how the ALARP approach to risk acceptability changes markedly when it comes to medical devices. For example. International Standard ISO 14971 [10] affords manufacturers the ability to justify risks on an ALARP basis. The European Commission Medical Device Directive (MDD) [11] cites ISO 14971 as a Harmonised Standard however the directive contains a number of Essential Requirements on risk acceptability which appear to conflict with ISO 14971. 

Biocompatibility is a very critical, basic safety requirement for medical polymers in medical device applications. For this, it is essential that ... 

Most sovereign nations have their own internal agencies to establish and enforce standards. However, in our present world of international cooperation and trade, standards are tending towards uniformity across national boundaries. This internationalization of standards is especially true since formation of the European Common Market. The aim here is to harmonize the standards of individual nations by promulgating directives for medical devices that address Essential Requirements (Freeman, 1993) (see below). Standards in other areas of the world (Asia, Eastern Europe) are much more fragmented, with each country specifying regulations for its own manufactured and imported medical devices. 

CE Mark, A CE Mark can be affixed to the medical device when all of the essential requirements of the MDD and other directives, as appropriate, are met. The declaration of conformity that contains the documented evidence that all requirements have been met achieves this. 

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