ISO/DIS 20432-4:2025(en)

ISO TC 173/WG 11

Secretariat: SIS

Date: 2025-03-07

Assistive products for tissue integrity when lying down – Part 4: Test methods for durability

© ISO 2025

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Contents

Foreword v

Introduction vi

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Common test equipment 2

4.1 Body analogue simulated weight 2

4.2 Sheet 2

5 Test method for determining the durability of an APTI placed on an articulated support platform 2

5.1 Scope and rationale 2

5.2 Test equipment 3

5.2.1 Test support platform 3

5.3 Test specifications 3

5.3.1 Number of cycles required 3

5.3.2 Evaluation criteria 4

5.4 Test method 4

5.5 Test report 4

6 Test method for determining the durability of an APTI to withstand user movement 4

6.1 Scope and rationale 4

6.2 Test equipment 4

6.2.1 Loading pad 4

6.3 Test specifications 5

6.3.1 Number of cycles required 5

6.3.2 Evaluation criteria 5

6.4 Test method 6

6.5 Test report 6

7 Test method for determining the durability of an APTI to withstand storage and operating environmental conditions 6

7.1 Scope and rationale 6

7.2 Test equipment 7

7.2.1 Environmental chamber 7

7.3 Test specifications 7

7.3.1 Testing conditions 7

7.3.2 Evaluation criteria 7

7.4 Test method 7

7.5 Test report 8

8 Test method for determining the durability of an APTI to withstand user repositioning on an APTI toward the head end of a bed 8

8.1 Scope and rationale 8

8.2 Test equipment 8

8.2.1 Repositioning sheet 8

8.2.2 Pulling fixture 8

8.3 Test specifications 8

8.3.1 Testing conditions 8

8.3.2 Evaluation criteria 8

8.4 Test method 9

8.5 Test report 9

9 Test report 9

Annex A (informative) Information about the validation tests conducted 11

A.1 Validation summary 11

Bibliography 12

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

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This document was prepared by Technical Committee ISO/TC 173 Assistive products.

A list of all parts in the ISO 20342 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Assistive products for tissue integrity (APTIs) play an integral role in any care plan for the prevention and treatment of pressure injuries. They can make a monumental difference in quality of life for any user with limited mobility. Since no one APTI is best for all users, a wide variety of APTIs, including mattresses, mattress overlays and integrated bed systems, are available in a broad array of materials. Choosing from this growing list of alternatives has become a daunting task for clinicians, care givers and users. Selecting from the available alternatives is further complicated by the lack of consistent information regarding APTI characteristics.

Clinicians, manufacturers, distributors and users all stand to benefit from the development of standardized procedures to evaluate the characteristics of APTI. Detailed information provided by standardized testing will help clinicians objectively match the characteristics of an APTI to the needs of individual users. Testing standards will also aid manufacturers by guiding new product development and in the redesign of existing products. Testing standards will promote quality assurance within the manufacturing process. Distributors too, will benefit by being able to clearly describe and compare products from multiple manufacturers. Lastly, users will benefit by having APTIs that truly support their needs.

This part of ISO 20342 includes the test methods for the evaluation of the durability of assistive products for tissue integrity (APTI) in the lying position in different application environments, such as hospitals, home care and institutions. Some of the devices can be used or reused in more than one application environment. This means that different test methods can be applied to the same APTI depending on the application environment. This document offers several test methods, not all of which will be appropriate for all APTIs, and therefore, the manufacturer is to determine which are appropriate for their APTIs’ construction and use.

APTIs play a very important role in the prevention and treatment of pressure injuries. Healthcare workers implementing prevention and treatment strategies, which include risk assessment, skin monitoring and repositioning. Guidance can be found in the NPIAP/EPUAP/PPPIA Guidelines, "Prevention and Treatment of Pressure Ulcers: Clinical Practice Guideline,” from 2019^[1].’

Assistive products for tissue integrity when lying down – Part 4: Test methods for durability

This part of ISO 20342 specifies conditions and test methods for the durability of assistive products for tissue integrity (APTI) when lying down additional to ISO 20342-1.

This document is applicable to APTIs, such as mattresses and overlays, and includes single patient multiple use products.

This document does not apply to single use products.

NOTE It is intended to help differentiate the durability characteristics between APTIs. It is not intended for determining overall performance or for ranking or scoring of such APTIs.

There are no normative references in this document.

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

durability

ability of a product to perform its required function over an expected period under normal conditions of use and maintenance

Note 1 to entry: Several units of measure can be used to express the expected lifetime of a product according to its field of application, such as years of life, hours of use or operational cycles.

Note 2 to entry: Different components of an APTI can have different life expectations.

3.2

single patient multiple use

<medical device, accessory> intended by the manufacturer to be reused on an individual user for multiple uses

[SOURCE: ISO 20417:2021,3.25, modified - Notes 1 and 2 were removed.]

3.3

single use

<medical device, accessory> intended by the manufacturer to be used on an individual user or specimen during a single procedure and then disposed of

[SOURCE: ISO 20417:2021,3.26, modified - Note 1 was removed.]

3.4

expected lifetime

manufacturer’s design life of the APTI or the period of time during which the APTI is safe to use and performs as intended by the manufacturer

The following test methods will reference these common pieces of testing equipment.

This is a mass of material (e.g. lead shot bags) held together in a fashion to simulate the size and shape of a user. This document will require 2 loading cases: one loading case is the maximum user weight of the APTI under test and the other loading case is the value where the mass would cover 90 % of the intended user population as defined by the manufacturer. The mass distribution of the simulated body weight should load each of the zones of the APTI in percentages per Figure 1. The body analogue simulated weight should be secured to ensure they maintain position during cycling.

The manufacturer may elect to run all test cycles at maximum user weight.

Key

Figure 1 — Mass distribution zones by percentage

Either fitted or flat sheet depending on the instructions for use of the APTI.

This method is used to evaluate the durability of an APTI intended to be used on an articulated (adjustable) mattress support platform. The test method simulates compressive and tensile loads at the bending points of the APTI that it would experience during intended use.

This test method is not valid for products which are not intended to be used when the support platform is articulated.

Plate or structure, capable of supporting the APTI and the test load applied during testing, with breather holes, approximately 6 mm in diameter and of approximately 20 mm pitch, provided to prevent air trapping under or in the APTI during testing and with dimensions as specified by the manufacturer representing the dimensions of a medical bed.

The back support section shall be adjustable to at least 70° (A), the upper leg section to at least 12° (B) and the lower leg section to least 20° (D) under horizontal, as shown in Figure 2.

Figure 2 — Test platform angle conditions

If the APTI is not prevented from moving during the durability test by the bed structure, it shall be prevented from moving by two side support profiles. The internal distance between the supports should be equal to the width of the mattress. The height of the support profiles should not exceed one third of the mattress thickness. The length of the support profiles should be at least equal to the length of the test unit.

If necessary, mattress pads shall be fixed during the tests by a suitable manner.

OR

Manufacturer may elect to use a bed frame or support platform with which the APTI is intended to be marketed. This shall only be allowed when the APTI’s instructions for use specifies that it is compatible with that specific product or platform.

The APTI being evaluated with this method shall be tested to the designed expected lifetime.

If the APTI has an expected lifetime based on time in use, follow these steps to determine the number of cycles required to test. Multiply the expected lifetime in years by a value of 5 000 cycles per year. This is the total number of cycles required to test to.

If the APTI has an expected lifetime based on number of cycles or other functions, the manufacturer will provide guidance on how to correlate this to an expected lifetime in years and then the same formula of 5 000 cycles per year shall be applied.

If the APTI is intended to only function for a certain number of cycles of articulation of the support platform, then that number of cycles shall be used as the expected lifetime.

NOTE The rationale for the number of cycles is as follows: Hospital and institution use was based on 3 cycles per day (3 meals per day and 10 cycles for turning or repositioning or toileting and therapy) for a yearly estimate of 5 000 cycles. Home care use was based 3 cycles per day (3 meals per day and 10 cycles for turning or repositioning or toileting and therapy) for a yearly estimate of 5 000 cycles.

To determine if the APTI meets the criteria of this test method, the following items shall be evaluated:

a) APTI shall be reviewed for indicators that the APTI would not meet its intended functions or impact safety per manufacturers risk analysis. The manufacturer shall be responsible for identifying what shall be reviewed on the APTI and the procedure for how it shall be reviewed.

NOTE Relevant tests can be conducted for the performance of intended specialized functions after cycling as per the test.

Complete any pre-test evaluations of the APTI as specified by the manufacturer. This may include performance testing and visual inspections of the APTI, as described in 5.3.2.

With the platform in the flat position, add the APTI and any other products as necessary for the APTI to function.

NOTE 1 Some products, such as mattress overlays or repositioning devices, can require the use of a primary APTI to fully evaluate them. The primary APTI can be selected by the manufacturer to enable testing of the ancillary APTI.

Install a sheet (4.2) onto the product according to the manufacturer's instructions for use. Place the body analogue simulated weights onto the APTI with a mass equal to the maximum user weight of the APTI. If the APTI has multiple control settings set the APTI to the worse case as defined by the manufacturer.

NOTE 2 If the position of the weight changes during the test, it can be fixed using a fixture.

Begin by articulating the support platform to its full range of travel as in intended use which would cause the maximum bending angle for the APTI as determined by the manufacturer. Return the mattress platform to its flat state. This constitutes one cycle.

The number of cycles executed with the maximum user weight on the product shall be 10 % of the overall number of cycles. For the remaining 90 % of the cycles, the body analogue weight shall be reduced to the specified value from clause 4.1.

The test report shall be in accordance with clause 9 of this document.

This method is used to simulate the ingress or egress of a user onto or off the APTI and the shifting or rotating of a user on the APTI in order to evaluate its durability. This simulates compressive loads at the ingress or egress locations on the APTI that it would experience during intended use.

Products which are not intended to be used when a user is ingressing or egressing from the support platform are deemed out of the scope of this testing.

Rigid circular object which is 355 +/- 5 mm in diameter with a convex spherical curvature of 800 mm radius with a 20 mm front edge radius, according to Figure 3.

NOTE Indenter is utilized across other standards such as IEC 60601-2-52^[3].

Figure 3 — Loading pad dimensions (in mm)

The APTI being evaluated with this method shall be tested to the designed expected lifetime.

If the APTI has an expected lifetime based on time in use, follow these steps to determine the number of cycles required to test. Multiply the expected lifetime in years by a value of 5 000 cycles per year. This is the total number of cycles required to test to.

If the APTI has an expected lifetime based on number of cycles or other functions, the manufacturer will provide guidance on how to correlate this to an expected lifetime in years and then the same formula of 5 000 cycles per year shall be applied.

If the APTI is intended to only function for a certain number of cycles of articulation of the support platform, then that number of cycles shall be used as the expected lifetime.

NOTE The rational for the number of cycles is as follows: Hospital and institution use was based on ingress and egress (3 meals per day and 10 cycles for turning or repositioning or toileting and therapy) for a total of 13 cycles per day for a yearly estimate of 5 000 cycles. Home care use was based on ingress and egress (3 meals per day and 10 cycles for turning or repositioning or toileting and therapy) for a total of 13 cycles per day for a yearly estimate of 5 000 cycles.

To determine if the APTI meets the criteria of this test method, the following items shall be evaluated:

a) APTI shall be reviewed for indicators that the APTI would not meet its intended functions or impact safety per manufacturers risk analysis. The manufacturer shall be responsible for identifying what shall be reviewed on the APTI and the procedure for how it shall be reviewed.

NOTE Relevant tests can be conducted for the performance of intended specialized functions after cycling as per the test.

Place APTI on a flat rigid horizontal surface or the prescribed support platform or frame, as described in 6.2.1, with mattress retainers, if required.

NOTE Some products (known as ancillary APTIs), such as mattress overlays or repositioning devices, can require the use of a primary APTI to fully evaluate them. The primary APTI can be selected by the manufacturer to enable testing of the ancillary APTI.

Install a sheet (4.2) onto the product according to the manufacturer's instructions for use. If the APTI has multiple control settings set the APTI to the worse case as defined by the manufacturer.

Apply a force by the means of the indenter onto the APTI equal to the maximum user weight for 20 % of the required cycles as specified in 6.3.1. Then apply a force by the means of the sacral indenter onto the APTI equal the reduced simulated weight value from section 4.1 for the remaining 80 % of the required cycles as specified in 6.3.1.

Testing location shall be at position A, as described in Figure 4. When using a primary and ancillary APTI the position of the testing location should be based on the primary APTI.

Key

Figure 4 — Position of indenter

The values above on percent weight breakdown for the test were based on the following: 20 % is based on matching the 1 000 cycles per year, taken from IEC 60601-2-52:2009+AMD1:2015,^[3] (10 000 cycles for a 10-year life) and the remaining 80 % are conducted at the value specified in clause 4.1.

The test report shall be in accordance with clause 9 of this document.

This method is intended to stress the APTI to the upper and lower limits of its storage and operating environmental conditions to determine the durability of the APTI at these conditions. This method is not intended to evaluate the long-term aging of products at these conditions but is only intended to evaluate the limits of the product to withstand the conditions.

Chamber or room capable of reaching the intended testing temperatures and humidity of the APTI.

Table 1 — Environmental specifications for APTI

Note Testing can be conducted according to manufacturer’s recommendations if they are outside of these limits.

The values given in Table 1 above for operation conditions are based on requirements outlined in IEC 60601-1:2006/AMD2:2020, Subclause 7.9.3.1^[4].

To determine if the APTI meets the criteria of this test method, the following items shall be evaluated:

a) APTI shall be reviewed for indicators that the APTI would not meet its intended functions or impact safety per manufacturers risk analysis. The manufacturer shall be responsible for identifying what shall be reviewed on the APTI and the procedure for how it shall be reviewed.

NOTE 1 Relevant tests can be conducted for the performance of intended specialized functions after conditioning as per the test.

NOTE 2 The performance characteristics are not intended to be evaluated at the temperature and humidity limits in this testing. They can be evaluated after conditioning to ensure conditioning did not impact the performance.

Place the APTI on a rigid horizontal surface (as described in section 5.2.1) or an intended compatible bed frame.

NOTE 1 Some products, such as mattress overlays or repositioning devices, can require the use of a primary APTI to fully evaluate them. The primary APTI can be selected by the manufacturer to enable testing of the ancillary APTI.

Place the system into an environmental chamber or conditioning room. If the APTI has multiple control settings set the APTI to the worse case as defined by the manufacturer. Expose the APTI to the range of storage temperatures and humidities (see Table 1) for a period of a minimum of 24 hours at each limit. Return the system to ambient conditions and review the APTI to ensure it is still functional.

NOTE 2 The limits test can be tested as individual limits or combined as possible by the equipment. An example profile can be: testing limit of -30 °C, testing limit of 15 % RH, testing combined limit of 50 °C and 90 % RH.

NOTE 3 If a user weight is required to evaluate the operability of the intended functions in the next section, then a user weight is added to the APTI at this time.

Bring the system up to the upper limit of operating temperatures and humidity (see 7.3.1) and dwell for 24 hours. Then verify the APTI is able to operate its intended functions properly.

Bring the system up to the lower limit of operating temperatures and humidity (see 7.3.1) and dwell for 24 hours. Then verify the APTI is able to operate its intended functions properly.

Return the system to ambient temperature. Then complete a full review of the evaluation criteria as specified.

The test report shall be in accordance with clause 9 of this document.

This method is used to simulate the effects on durability of the APTI, when a user is often repositioned to the head end of the bed. The test simulates shear loads in the APTI that it would experience during intended use. Users on an APTI may migrate toward the foot end of the product over time, this can be accelerated with elevation of back support and requires the user to be repositioned toward the head end of the APTI to reset their body to the proper position. This test method reproduces this migration toward the foot end of the APTI and the forces to reposition the user toward the head end.

Products which are not intended to be used when a user is being repositioned toward the head end of the bed are deemed out of the scope of this testing.

Resilient material to grip onto with pulling fixture to pull the simulated user weight to slide over the top of the sheet on the APTI.

Fixture with the ability to pull horizontally on the repositioning sheet with sufficient force to transfer the simulated weight 150 mm.

The APTI being evaluated according to this method shall be tested to the designed expected lifetime.

If the APTI has an expected lifetime based on time in use, follow these steps to determine the number of cycles required to test. Multiply the expected lifetime in years by a value of 2 500 cycles per year. This is the total number of cycles required to test to.

If the APTI has an expected lifetime based on number of cycles or other functions, the manufacturer will provide guidance on how to correlate this to an expected lifetime in years and then the same formula of 2 500 cycles per year shall be applied.

If the APTI is intended to only function for a certain number of cycles of articulation of the support platform, then that number of cycles shall be used as the expected lifetime.

NOTE The rationale for number of cycles is as follows: Hospital and institution use was based on 1 repositioning per meal (3 meals per day and 3 other repositioning) for a yearly estimate of 2 500 cycles or repositioning needed during turning procedures to re-centre the user (6 times per day for a yearly estimate of 2 500 cycles).

To determine if the APTI meets the criteria of this test method, the following items shall be evaluated:

a) APTI shall be reviewed for indicators that the APTI would not meet its intended functions or impact safety per manufacturers risk analysis. The manufacturer shall be responsible for identifying what shall be reviewed on the APTI and the procedure for how it shall be reviewed.

NOTE Relevant tests can be conducted for the performance of intended specialized functions after cycling as per the test.

Place APTI on a flat rigid horizontal surface or the prescribed support platform or frame, as described in 5.2.1, with mattress retainers, if required.

NOTE Some products, such as mattress overlays or repositioning devices, can require the use of a primary APTI to fully evaluate them. The primary APTI can be selected by the manufacturer to enable testing of the ancillary APTI.

Install a sheet (4.2) onto the base mattress or APTI. Then place the repositioning sheet (8.2.1) and body analogue simulated weight (4.1) on the system. If the APTI has multiple control settings set the APTI to the worse case as defined by the manufacturer.

Using the pulling fixture, pull the simulated weight a minimum of 150 mm toward the head end of the APTI. Using the pulling fixture, pull the simulated weight back down to the foot end of the APTI a minimum of 150 mm to its starting position. This constitutes one cycle.

The number of cycles executed with the maximum user weight on the product shall be 10 % of the overall number of cycles. For the remaining 90 % of the cycles, the body analogue weight shall be reduced to the specified value from clause 4.1.

The test report shall be in accordance with clause 9 of this document.

The test report shall contain the following information:

a) unique report number;

b) the name, address and the specific accreditation number of the test institute, if applicable;

c) the date of issue of the test report;

d) reference to this document, i.e., ISO 20342-4;

e) the name and address of the manufacturer of the assistive product;

f) a description of the sample including the manufacturer's or distributor’s trademark, model or type;

g) other APTIs or products in combination (e.g., primary APTI used to evaluate an ancillary APTI);

h) serial number and any variations or accessories fitted;

i) the source of the sample;

j) where the controller is programmable, the settings used while testing;

k) a photograph of the sample equipped during the test;

l) the results of the tests including record of maintenance, if any;

m) a statement of whether or not the tested sample met all of the applicable criteria of this document and a list of all the failed criterion;

n) a statement of which alternate, or additional, device-specific standards have been applied;

o) any deviations from the test methods (e.g. storage and operating conditions deviations to match manufacturer's recommendations)

p) test conditions used to perform the test, e.g. use of heated indenter.

1. 
   (informative)
   
   Information about the validation tests conducted
   1. Validation summary

The working group agreed that for the validation of this part of the ISO 20342 standard the plan was to validate that the procedure was clear and executable. To complete the validation activity, two test laboratories were selected to execute the standard on an APTI of their choice. Each test laboratory ran through all of the clauses of the standard for an expected lifetime of 1 year.

The results of this validation work were then presented to the working group to review the observations during execution. This validation activity led to improved commonization across the clauses of the standard and identified a few minor typos.

Bibliography

[1] Guidelines N.P.I.A.P. https://npiap.com/page/InternationalGuidelines

[2] ISO 20342‑1:2022, Assistive products for tissue integrity when lying down — Part 1: General requirements

[3] IEC 60601‑2-52:2009+AMD1:2015, Medical electrical equipment-Particular requirements for basic safety and essential performance of medical beds

[4] IEC 60601‑1:2005/AMD2:2020, Medical electrical equipment. Part 1: General requirements for basic safety and essential performance