3
ical devices directive is due to into force in Europe in June anufacturers and suppliers of wheelchairs will have to comply with this directive to make their products available on the European market. European stan- dards for wheelchairs are being written to help people demonstrate compliance with the directive. This article summarizes the content of these standards and how they are likely to be implemented. Geoff Bordsley Tayside Rehabilitation Engineering Services, Dundee limb Fitting Centre ERs of all the relevant directives. In some cases, more than one directive will be in- volved. It is for the manufacturer to decide which directive(s) apply to hisker prod- ucts. Wheelchairs, through their purpose of mitigating disability, are closely aligned to one of the directives on medical devices [ 11, Background In the past, European countries have developed national legislation, often supported by national standards for technical Standards products sold within their Each directive is written in country. Inevitably, there general terms so that it ap- have been significant di l’i’.hi. IiIi~~ ::- li!il; design re- ences among differ,*ii, country’s standards, re I I I I’,~I :i i iii i \ b l y, this gen- sulting in products of , i*~:~ii~! :.l-o means that widely varying iliL> i1:.ii:iiI’acturer has safety, compatibil- rL*.liiI:i. ibility for in- d ity, quality, etc. 1\11 ~li.~*iation of the This confusion has iI I rective as 3 created problems well as for 2 for manufacturers con f or- o selling products in a mity. number of countries The Euro- and has stifled trade pean Council, within Europe. consequently, has commissioned the CEN (European Committee for Standardisation)to develop standards, called harmonized stan- dards, which can be used by the manufac- turer as one way of demonstrating conformity with nominated ERs. The use of these standards is voluntary, as the manufacturer can choose any way that he wishes to demonstrate conformity with the requirements. However, if he chooses to conform to a harmonized standard, he then has a “legal presumption of conformity” with the ERs nominated within an annex of the standard. - - Directives & Essential Requirements In the mid 1980% the European Parlia- ment agreed, as apriority task, to eliminate these barriers to trade by harmonizing stan- dards across Europe. The first visible stage of this harmonization was the issuing of a series of directives for major product groups. The medical devices product groups are covered by three medical devices directives. Directives are legisla- tive documents from the European Coun- cil, and they lay down essential requirements (ERs) relating to safety, health, quality, labelling, etc. Anyone sell- ing or providing products within these groups must comply with all the relevant Level of Standards Where there are common require- ments for a group of products, it is CEN policy to bring them together in one stan- dard, whenever possible. This policy has lead to the concept of “levels of stan- dards.” Level 1 standards either bring together a range of common requirements for a large group of products or specify the re- quirements for a specific aspect that ap- plies to a range of products. Thus, EN 12182 [2] specifies the requirements for the very large field of technical aids; and EN 1441 [3] specifies the requirements for risk-analysis procedures for all medi- cal devices. Both are level 1 standards. Level 2 standards specify the require- ments for groups of products, and level 3 standards set requirements for particular products. For example there are level 2 standards for orthopedic implants and level 3 standards for individual prosthe- ses. This structure enables lower, more specific standards to cite higher level standards, and it provides better consis- tency across “families” of standards. Within the medical devices directive the (level 2) wheelchair standards contain normative references to the (level 1) stan- dards for technical aids andrisk analysis. Wheelchair Standards Two level 2 standards are being devel- . Manual wheelchairs - EN12183 [4] . Powered wheelchairs -EN12184 [5] This work is controlled by CEN Tech- nical Committee TC293, which consists of representatives of the European National Standardisation Bodies. The standards are being written by Working Group 2 of this technical committee. This group consists of individual experts nominated by each country. It commenced work in spring 1992 and aims to complete these two stan- dards and make them available for use be- fore June 1998, when the medical devices directive becomes mandatory. These documents are quite unlike I S 0 wheelchair standards in that they contain a wide variety of requirements necessary to comply with the directive. They do, however, make extensive use, wherever possible, of IS0 standards for test meth- oped for wheelchairs as follows: 42 IEEE ENGINEERING IN MEDICINE AND BIOLOGY 0739-5175/98/$10.0001998 Moy/June 1998

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Page 1: European standards for wheelchairs

ical devices directive is due to into force in Europe in June anufacturers and suppliers of

wheelchairs will have to comply with this directive to make their products available on the European market. European stan- dards for wheelchairs are being written to help people demonstrate compliance with the directive. This article summarizes the content of these standards and how they are likely to be implemented.

Geoff Bordsley Tayside Rehabilitation Engineering Services,

Dundee l imb Fitting Centre

ERs of all the relevant directives. In some cases, more than one directive will be in- volved.

It is for the manufacturer to decide which directive(s) apply to hisker prod- ucts. Wheelchairs, through their purpose of mitigating disability, are closely aligned to one of the directives on medical devices [ 11,

Background In the past, European countries have

developed national legislation, often supported by national standards for technical Standards products sold within their Each directive is written in country. Inevitably, there general terms so that it ap- have been significant di l ’ i ’ . h i . I i I i ~ ~ ::- li!il; design re- e n c e s a m o n g differ ,*i i , country’s standards, re I I I I ’ , ~ I :i i i i i i \ b l y, this gen- sulting in products of , i * ~ : ~ i i ~ ! :.l-o means that wide ly v a r y i n g iliL> i1:.ii:iiI’acturer has safety, compatibil- rL*.liiI:i. ibility for in-

d i t y , qual i ty , e t c . 1 \ 1 1 ~li.~*iation of the This confusion has i I I rective as

3 created problems well as for 2 for manufacturers con f or- o selling products in a m i t y .

number of countries The Euro- and has s t i f l ed t r ade pean Council, within Europe. consequently, has commissioned the CEN

(European Committee for Standardisation) to develop standards, called harmonized stan- dards, which can be used by the manufac- turer as one way of demonstrating conformity with nominated ERs. The use of these standards is voluntary, as the manufacturer can choose any way that he wishes to demonstrate conformity with the requirements. However, if he chooses to conform to a harmonized standard, he then has a “legal presumption of conformity” with the ERs nominated within an annex of the standard.

- -

Directives & Essential Requirements

In the mid 1980% the European Parlia- ment agreed, as apriority task, to eliminate these barriers to trade by harmonizing stan- dards across Europe. The first visible stage of this harmonization was the issuing of a series of directives for major product groups. The medical devices product groups are covered by three medical devices directives. Directives are legisla- tive documents from the European Coun- ci l , and they lay down essent ia l requirements (ERs) relating to safety, health, quality, labelling, etc. Anyone sell- ing or providing products within these groups must comply with all the relevant

Level of Standards Where there are common require-

ments for a group of products, it is CEN policy to bring them together in one stan-

dard, whenever possible. This policy has lead to the concept of “levels of stan- dards.”

Level 1 standards either bring together a range of common requirements for a large group of products or specify the re- quirements for a specific aspect that ap- plies to a range of products. Thus, EN 12182 [2] specifies the requirements for the very large field of technical aids; and EN 1441 [3] specifies the requirements for risk-analysis procedures for all medi- cal devices. Both are level 1 standards.

Level 2 standards specify the require- ments for groups of products, and level 3 standards set requirements for particular products. For example there are level 2 standards for orthopedic implants and level 3 standards for individual prosthe- ses. This structure enables lower, more specific standards to cite higher level standards, and it provides better consis- tency across “families” of standards. Within the medical devices directive the (level 2) wheelchair standards contain normative references to the (level 1) stan- dards for technical aids andrisk analysis.

Wheelchair Standards Two level 2 standards are being devel-

. Manual wheelchairs - EN12183 [4] . Powered wheelchairs -EN12184 [5] This work is controlled by CEN Tech-

nical Committee TC293, which consists of representatives of the European National Standardisation Bodies. The standards are being written by Working Group 2 of this technical committee. This group consists of individual experts nominated by each country. It commenced work in spring 1992 and aims to complete these two stan- dards and make them available for use be- fore June 1998, when the medical devices directive becomes mandatory.

These documents are quite unlike IS0 wheelchair standards in that they contain a wide variety of requirements necessary to comply with the directive. They do, however, make extensive use, wherever possible, of IS0 standards for test meth-

oped for wheelchairs as follows:

42 IEEE ENGINEERING IN MEDICINE AND BIOLOGY 0739-5175/98/$10.0001998 Moy/June 1998

Page 2: European standards for wheelchairs

ods to determine the performance of the wheelchairs. In fact, considerable pres- sure to speed up IS0 standards work has been applied to meet the deadlines for CEN work.

Some additional requirements and test methods have been dev1:loped specifi- cally for the CEN standard, but these are small in number, with the preference be- ing for this work to be done in ISO.

Unfortunately, it has not been possible to find test methods for all aspects to meet the ERs. In these cases, some guidance may be provided, but manufacturers are left to their own methods of proving com- pliance with that particular ER.

Axelson, et al. [6], provide a valuable summary of the ANSI/RESNA interpreta- tion of the IS0 Wheelchair Standards and their application to wheelchair selection. References 171 to [27] list all the relevant IS0 Standards.

Powered Wheelchair Standard The following section summarizes the

contents of the standard for powered wheelchairs. There are five main sections comprising general requirements, per- formance requirements, electrical re- quirements, information requirements, and a series of informative annexes.

It is not the intention of the standard to inhibit the development cf design, hence there are just a few desig,n requirements included. These relate to a few basic com- ponents such as footrest 'design, braking systems, battery enclosures, restraint sys- tems for use within a vehicle (if fitted), anti-tip devices, etc.

The major content of ihe standard re- lates to performance requirements. IS0 7176, Part 8, Strength Testing [14] forms the core of this part of the standard. Addi- tional tests are specifkd for fatigue strength of manually operated parking brakes and joysticks. An innovative part of the standard is the division of wheel- chairs into three categories based on in- tended usage: indoor, indoor and outdoor, primarily outdoors. Perfoimance require- ments are then specified for these differ- ent categories, based on I S 0 test methods from the 7 176 series of wheelchair stan- dards. These requirements include dy- namic stability [8], static stability [7], brake effectiveness [9], maximum speed [12], obstacle climbing z.bility [16], en- ergy consumption [lo], and overall di- mensions (including turning space) [ 1 l l . Additional test methods are specified, along with requirements fix climbing and

descending slopes, noise emission, and water resistance.

The standard goes into some detail to specify electrical requirements for pow- ered wheelchairs. Again, these rely on the IS0 7176 series, this time using Part 14 [191 as the core requirement. In addition, there are some features required to be in- corporated into the design of the wheel- chair, such as power indicators, circuit protection, access to controllers, disen- gagement of automatic brakes, battery connections, and battery chargers. This part of the standard extends to require- ments for electromagnetic emissions and susceptibilities to electromagnetic fields and electrostatic discharges. At present, there is some debate over the field strength to be used in the test for electro- magnetic susceptibility. It is intended that the work here will converge with parallel work presently in progress in ISO, where Committee Draft 7176-21 [26] relating to this subject has just received approval. The standard extends to cover require- ments for information to be supplied by the manufacturer. This point follows closely the requirements specified in I S 0 7 176 Part 15 [201, along with a number of additional items of information. The pri- mary additions relate to the introduction of the classification of wheelchairs, and hence the need to provide information re- lating to the results of these extra tests.

The standard includes a sequence of informative annexes that give recommen- dations for manufacturers to consider in their wheelchair design, either for which a standard was too difficult to develop or for which it was not felt sufficiently impor- tant to write a test method. These annexes are intended to provide useful information to guide manufacturers, particularly to- ward a good ergonomic device design.

Finally, a checklist is included to indi- cate which of the ERs of the medical devices directive are covered in the stan- dard and, possibly more significantly, which are not covered. In the latter case, manufacturers will have to determine their own means of showing compliance with the remaining ERs.

Manual Wheelchair Standard The standard for manual wheelchairs

is very similar to the powered wheelchair standard with, obviously, the exclusion of the requirements for electrical systems. These are replaced by some requirements relating to performance of the propulsion of the wheelchair.

IEEE ENGINEERING I N MEDICINE AND BIOLOGY

An innovative part

of'the standard is

the division of'

wheelchairs into three

catagories based

on intended usage.

The standard commences with a number of design requirements relating to features of the chair. These include foot- rests and legrests, tires, seat belts, arm- rests and backrests, and requirements for restraints should the wheelchair be in- tended to be used as a seat in a vehicle. Further requirements relate to parking brakes, service brakes, maximum compo- nent weight, and the fitting of anti-tip de- vices.

The key performance requirements are based on IS0 7176-8, Strength Testing [14]. Additional tests are included for parking-brake effectiveness, fatigue strength, and operating forces. A maxi- mum pushing force is specified for the loaded wheelchair, and there is a require- ment for the tracking characteristics.

Again, considerable emphasis is placed on manufacturers supplying ap- propriate information, as specified in IS0 7176 Part 15 [20]. A number of additional requirements are included for information to be supplied. Most notably, these in- clude labeling for warning if a chair can be adjusted to a low level of stability.

Informative annexes provide recom- mendations for good design and perform- ance features to be considered by manufacturers. Finally, a checklist is in- cluded to indicate which ERs are covered

43

Page 3: European standards for wheelchairs

by the standard and which need further at- tention by the manufacturer.

Current Progress The Manual Wheelchairs Standard (EN

12184) [5] has been drafted and has re- ceived approval in its first stage of voting, termed “preliminary enquiry” or prEN. It is now being prepared for circulation for For- mal Voting (the final vote) which, if ap- proved, will shortly be completed.

The Powered Wheelchairs Standard (EN12183) [4] has similarly been drafted and circulated for prEN voting. Difficul- ties are being experienced in agreeing on the EMC immunity requirements, and de- lays have occurred in progress of the stan- dard. These difficulties will be resolved shortly, either by agreeing on required levels of immunity or by placing these in an informative annex to keep the standard on target for completion.

Implementation All the countries in the European Un-

ion are required to suspend all work on the development of conflicting national stan- dards, and when harmonized standards are published, any conflicting national standards must be withdrawn.

After June 1998, all wheelchairs sold or supplied in Europe will, by law, have to comply with the medical devices directive and will have to be labeled to show their compliance. This label is the CE mark, which is already coming into use.

There may be several agencies in the chain of supply of a wheelchair to a wheelchair user: from component sup- plier, to manufacturer, to retailer, to health-service provider. Responsibility for conforming to the directives lies with the manufacturer, with everyone else in the chain having their own responsibili- ties under other laws.

There is little proactive policing of compliance with the directives as applied to wheelchairs, b u t any investigation of defects will lead to examination of the manufacturer’s documentation, with the likelihood of criminal prosecution if the requirements have not been met.

Implications The medical devices directive will

have the major effect of removing trade barriers within Europe and will clearly benefit manufacturers. However, the work involved in ensuring compliance and testing is likely to be very extensive and costly. Inevitably, these costs will be

passed on to the purchaser, making wheel- chairs more expensive. This may also in- hibit the development of new devices, particularly for smaller businesses that may not have resources for testing. Con- versely, the prescriber/purchaser will have vastly improved quality and quantity of information about products, so as to make better choices. Standards will also ensure that products are safe and fit for the purposes intended.

Acknowledgment The author is indebted to Mr. Bill

Walmsley for his assistance with check- ing this script and suggesting improve- ments.

Geoff Bardsley graduated in Electrical and Electronic Engineering at Liverpool University in 1973. He then completed a PhD at Strathclyde University in 1977 studying the relationship of body move- ment and the causes of pressure sores.

His subsequent employment has been with Tayside Rehabilitation Engineering Services and Dundee University whlst based at Dundee Limb Fitting Centre. During this period he has been involved in research and development relating to wheelchairs and seat- ing. His primary role now relates to mnning NHS services for the provision of these de- vices throughout Tayside.

Dr. Bardsley has been involved in wheelchair standards since 1985 and con- vened the CEN Working Group (CEN TC293 WG2) for the initial three years of development of the European Standards for wheelchairs. He has been convenor of the IS0 Worlung Group for Wheelchair Test Methods (IS0 TC173 SC1 WG1) for the past seven years.

Address for Correspondence: 133 Queen Street, Broughty Ferry, Dundee DD5 lAG, Scotland. Tel: 44 (0) 1382 730104. Fax: 44 (0) 1382 480194. E-mail gibardsley @ dth.scot.nhs .uk

References 1. Council of European Communities: Medical devices directive. Journal of European Commu- nities, 93/42/EEC, L169, July 1993. 2. CEN: prEN 12182: Technical aids for disabled persons-General requirements and test methods. 3. CEN: prEn 1441: Medical devices-Riskanalysis. 4. CEN: prEN 12183: Manually propelled wheelchairs-Requirements and test methods. 5. CEN: prEN 12184: Electrically powered wheelchairs, scooters and their chargers- Requirements and test methods.

6. Axelson P, Minke1 J, Chesney D: A guide to wheelchair se lec t ion : how to use the ANSVRESNA wheelchair standards to buy a wheelchair. Paralyzed Veterans of America, Washington, D.C. 20006, 1994. 7. ISO: 7176.1 Wheelchairs-Part 1: Determina- tion of static stability. 8. ISO: 7176-2 Wheelchairs -Part 2 Determina- tion of dynamic stability of electric wheelchairs. 9. ISO: 7176-3 Wheelchairs-Part 3: Determina- tion of efficiency of brakes. 10. ISO: 7176- 4 Wheelchairs-Part 4: Determina- tion of energy consumption of electric wheel- chairs. 11. ISO: 7 176-5 Wheelchairs-Part 5: Determina- tion of overall dimensions, mass and turning space. 12. ISO: 7 176-6 Wheelchairs-Part 6: Determina- tion of maximum speed, acceleration and retarda- tion of electric wheelchairs. 13. ISO: 7 176-7 Wheelchairs-Part 7: Determina- tion of seating dimensions-Definitions and meas- uring methods. 14. ISO: FDIS 7176-8 Wheelchairs-Part 8: Re- quirements and test methods for static, impact and fatigue strength. 15. ISO: 7176-9 Wheelchairs-Part 9: Climatic tests for electric wheelchairs. 16. ISO: 7176-10 Wheelchairs-Part 10: Determi- nation of obstacle-climbing ability of electric wheelchairs. 17.IS0:7176-11Wheelchairs-Part11:Testdu”ies 18. KO: 7176.13 Wheelchairs-Part 13: Determi- nation of coefficient of friction of test surfaces. 19. ISO: FDIS 7176-14 Wheelchairs-Part 14: Power & controls for electric wheelchairs- requirements and test methods. 20. ISO: 7176-15 Wheelchairs-Part 15: Require- ments for information disclosure, documentation and labelling. 21. ISO: 7176-16 Wheelchairs-Part 16: Require- ments and test methods for resistance to ignition of upholstered parts. 22. ISO: CD 7176-17 Wheelchairs-Part 17: Serial interface for electric wheelchair controllers. 23. ISO: CD 7176-18 Wheelchairs-Part 18: Stair traversing devices. 24. ISO: CD 7176-19 Wheelchairs-Part 19: Wheeled mobility devices for use in motor vehi- cles. 25. ISO: CD 7176-20 Wheelchairs-Part 20: De- termination of the performance of stand-up wheelchairs. 26. KO: DIS 7176-21 Wheelchairs-Part 21: Re- quirements and test methods for electromagnetic compatibility of powered wheelchairs and motor- ized scooters. 27. ISO: DIS 7176-22 Wheelchairs-Part 22: Set up procedures for adjustable wheelchairs. 28. ISO: CD 10542 Wheelchairs-Tiedown and occupant restraint systems for motor vehicles- Parts 1 to 5.

prEN = preliminary enquiry, first stage formal CEN voting document FDIS = Final draft International Standard DIS = Draft International Standard CD = Committee draft

44 IEEE ENGINEERING IN MEDICINE AND BIOLOGY M o y / J u n e 1998