ASTM F3172-15(2021)
(Guide)Standard Guide for Design Verification Device Size and Sample Size Selection for Endovascular Devices
Standard Guide for Design Verification Device Size and Sample Size Selection for Endovascular Devices
SIGNIFICANCE AND USE
4.1 The purpose of this guide is to provide guidance for selecting appropriate device size(s) and determining appropriate sample size(s) for design verification of endovascular devices. The device size(s) and sample size(s) for each design input requirement should be determined before testing. The device size(s) selected for verification testing should establish that the entire device matrix is able to achieve the design input requirements. If testing is not performed on all device sizes, justification should be provided.
4.2 The sample size justification and statistical procedures used to analyze the data should be based on sound scientific principles and should be suitable for reaching a justifiable conclusion. Insufficient sample size may lead to erroneous conclusions more often than desired.
4.3 Guidance regarding methodologies for determining device size selection and appropriate sample size is provided in Sections 5 and 6.
SCOPE
1.1 This guide provides guidance for selecting an appropriate device size(s) and determining an appropriate sample size(s) (that is, number of samples) for design verification testing of endovascular devices. A methodology is presented to determine which device size(s) should be selected for testing to verify the device design adequately for each design input requirement (that is, test characteristic). Additionally, different statistical approaches are presented and discussed to help guide the developer to determine and justify sample size(s) for the design input requirement being verified. Alternate methodologies for determining device size selection and sample size selection may be acceptable for design verification.
1.2 This guide applies to physical design verification testing. This guide addresses in-vitro testing; in-vivo/animal studies are outside the scope of this guide. This guide does not directly address design validation; however, the methodologies presented may be applicable to in-vitro design validation testing. Guidance for sampling related to computational simulation (for example, sensitivity analysis and tolerance analysis) is not provided. Guidance for using models, such as design of experiments (DOE), for design verification testing is not provided. This guide does not address sampling across multiple manufacturing lots as this is typically done as process validation. Special considerations are to be given to certain tests such as fatigue (see Practice E739) and shelf-life testing (see Section 8).
1.3 Regulatory guidance may exist for endovascular devices that should be considered for design verification device size and sample size selection.
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:F3172 −15 (Reapproved 2021)
Standard Guide for
Design Verification Device Size and Sample Size Selection
for Endovascular Devices
This standard is issued under the fixed designation F3172; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This guide provides guidance for selecting an appropri-
mine the applicability of regulatory limitations prior to use.
ate device size(s) and determining an appropriate sample
1.6 This international standard was developed in accor-
size(s) (that is, number of samples) for design verification
dance with internationally recognized principles on standard-
testing of endovascular devices.Amethodology is presented to
ization established in the Decision on Principles for the
determinewhichdevicesize(s)shouldbeselectedfortestingto
Development of International Standards, Guides and Recom-
verify the device design adequately for each design input
mendations issued by the World Trade Organization Technical
requirement (that is, test characteristic).Additionally, different
Barriers to Trade (TBT) Committee.
statisticalapproachesarepresentedanddiscussedtohelpguide
the developer to determine and justify sample size(s) for the
2. Referenced Documents
design input requirement being verified. Alternate methodolo-
2.1 ASTM Standards:
gies for determining device size selection and sample size
E739 PracticeforStatisticalAnalysisofLinearorLinearized
selection may be acceptable for design verification.
Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
1.2 This guide applies to physical design verification test-
F2914 Guide for Identification of Shelf-life Test Attributes
ing. This guide addresses in-vitro testing; in-vivo/animal stud-
for Endovascular Devices
ies are outside the scope of this guide. This guide does not
2.2 ISO Standards:
directly address design validation; however, the methodologies
ISO 14971:2012 Medical devices—Application of risk man-
presented may be applicable to in-vitro design validation
agement to medical devices
testing. Guidance for sampling related to computational simu-
lation (for example, sensitivity analysis and tolerance analysis) 3. Terminology
is not provided. Guidance for using models, such as design of
3.1 Definitions:
experiments (DOE), for design verification testing is not
3.1.1 attribute data, n—data that identify the presence or
provided.Thisguidedoesnotaddresssamplingacrossmultiple
absenceofacharacteristic(forexample,good/badorpass/fail).
manufacturing lots as this is typically done as process valida-
3.1.2 design input requirements, n—physical and perfor-
tion.Specialconsiderationsaretobegiventocertaintestssuch
mance requirements of a device that are used as a basis for
asfatigue(seePracticeE739)andshelf-lifetesting(seeSection
device design (typically defined as test characteristics such as
8).
balloon burst pressure, shaft tensile strength, and so forth).
1.3 Regulatoryguidancemayexistforendovasculardevices
3.1.3 design output, n—features of the device (that is,
that should be considered for design verification device size
dimensions, materials, and so forth) that define the design and
and sample size selection.
make it capable of achieving design input requirements.
1.4 Units—The values stated in SI units are to be regarded
3.1.4 design subgroup, n—set defined by the device sizes
as the standard. No other units of measurement are included in
within the device matrix in which the essential design outputs
this standard.
do not vary for a specified design input requirement (that is,
1.5 This standard does not purport to address all of the
device sizes that share the same design for a specified design
safety concerns, if any, associated with its use. It is the
input requirement).
1 2
This guide is under the jurisdiction of ASTM Committee F04 on Medical and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Surgical Materials and Devices and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
F04.30 on Cardiovascular Standards. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Aug. 1, 2021. Published August 2021. Originally the ASTM website.
approved in 2015. Last previous edition approved in 2015 as F3172 – 15. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/F3172-15R21. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3172−15 (2021)
3.1.5 design validation, n—establishing by objective evi- Testing the same device size(s) is typically not appropriate to
dence that the device conforms to defined user needs and verify all design input requirements. Differences in the device
intended use(s). design throughout the device matrix will drive which device
size(s) is selected for verification of each design input require-
3.1.6 design verification, n—confirmation by examination
ment.
and provision of objective evidence that the device design
5.1.1 As explained in subsequent sections, when determin-
(design output) fulfills the specified requirements (design
ing device size(s) for testing, the following should be consid-
input).
ered for each design input requirement:
3.1.7 device matrix, n—entire range of available models/
5.1.1.1 Essential design outputs,
sizes for the device family.
5.1.1.2 Design subgroups, and
3.1.8 device size, n—individual model/size (for example,
5.1.1.3 Other considerations.
6 mm diameter by 25 mm length balloon on 135 cm length
5.2 Define Essential Design Outputs (EDOs)—The design
catheter or a 6Fr 100 cm length guide catheter).
outputs of the device are the features of the device (that is,
3.1.9 endovascular device, n—device used to treat vascular
dimensions, materials, and so forth) that define the design and
conditions from within the vessel.
makeitcapableofachievingdesigninputrequirements.Notall
3.1.10 essential design output, EDO, n—designfeature(s)or design outputs are essential for each design input requirement.
characteristic(s) of the device that affects its ability to achieve
Therefore, for each design input requirement, the essential
the design input requirements (that is, design output(s) that has design outputs (EDOs) should be identified. In Table 1,
a relevant effect on the test results).
example EDOs for design input requirements of a balloon
catheter device are provided.
3.1.11 process validation, n—establishment by objective
evidence that a process consistently produces a result or device
5.3 Define Design Subgroups:
achieving its predetermined requirements.
5.3.1 The design subgroups should be defined for each
design input requirement based on the EDOs identified.
3.1.12 safety factor, n—ratio of the device performance to
5.3.2 For a specific design input requirement, the design
the specification requirement (for example, how much stronger
subgroups can be defined as one of the following:
the device is than it needs to be to meet its specification
5.3.2.1 The entire device matrix if the EDOs for the design
requirement).
input requirement are constant throughout the entire device
3.1.13 sample size, n—quantityofindividualspecimensofa
matrix,
device tested.
5.3.2.2 Subsets of the device matrix if the EDOs for the
3.1.14 variables data, n—data that measure the numerical
design input requirement vary in groups or stages throughout
magnitude of a characteristic (how good/how bad).
the device matrix, or
5.3.2.3 Each individual device size of the device matrix if
4. Significance and Use
EDOs for the design input requirement are different for each
4.1 The purpose of this guide is to provide guidance for
individual device size.
selecting appropriate device size(s) and determining appropri-
5.3.3 Fig. 1 represents the device matrix (entire range of
ate sample size(s) for design verification of endovascular
available device sizes) for a 135 cm length balloon catheter
devices. The device size(s) and sample size(s) for each design
device that has balloon diameters ranging from 3 to 7 mm and
input requirement should be determined before testing. The
balloon lengths ranging from 10 to 50 mm. Balloon catheters
device size(s) selected for verification testing should establish
are available in any combination of balloon diameter and
that the entire device matrix is able to achieve the design input
length resulting in 25 unique device sizes in the device matrix.
requirements. If testing is not performed on all device sizes,
5.3.4 Figs. 2-4 illustrate how the device matrix in Fig. 1 is
justification should be provided.
defined by different design subgroups for different design input
4.2 The sample size justification and statistical procedures
used to analyze the data should be based on sound scientific
TABLE 1 Example EDOs for Design Input Requirements for a
principles and should be suitable for reaching a justifiable
Balloon Catheter Device
conclusion. Insufficient sample size may lead to erroneous
Design Input Requirement EDOs
conclusions more often than desired.
Manifold connection/Luer lockability Luer thread dimensions
4.3 Guidance regarding methodologies for determining de-
Manifold material
vice size selection and appropriate sample size is provided in
Catheter shaft tensile strength for a Shaft material
Sections 5 and 6.
single lumen catheter Shaft cross-sectional area
(diameter and wall thickness)
5. Selection of Device Size(s)
Shaft bond design
5.1 Design input requirements are the physical and perfor-
Balloon compliance (diameter versus Balloon diameter
mance requirements of a device that are used as a basis for
pressure) Balloon material
device design. Once the device design is defined, testing is Balloon wall thickness
typicallyperformedtoverifythatthedesigninputrequirements
Balloon deflation time Balloon volume
are met. The appropriate device size(s) for verification testing
Shaft deflation lumen design
should be determined for each design input requirement.
F3172−15 (2021)
FIG. 1Device Matrix for a Balloon Catheter Device (25 unique device sizes)
FIG. 2Design Subgroup for Manifold Connection/Luer Lockability Testing (EDOs remain constant throughout the device matrix)
requirements. Fig. 2 represents a design subgroup that is subgroup that is defined by the device sizes that have shaft
defined by the entire device matrix because all device sizes design “B.” Fig. 4 represents design subgroups for balloon
share the same design for the specified design input require- compliance in which each balloon diameter defines a unique
ment (that is, the EDOs remain constant for all device sizes). design subgroup.
The design input requirement is manifold connection/luer
5.4 Design Input Requirements and Other
lockability testing, and the EDOs (luer thread dimensions and
Considerations—In addition to design subgroup definition,
manifold material) are the same for all sizes in the device
design input, device labeling, or regulatory requirements may
matrix.
make it necessary to test additional sizes.
5.3.5 Figs. 3 and 4 represent design subgroups that are
5.5 Device Size Selection Approach:
subsets of the device matrix because the EDOs for the design
5.5.1 Approach—Once the design subgroups are defined for
input requirement vary throughout the device matrix. Fig. 3
agivendesigninputrequirement,thedevicesize(s)tobetested
represents design subgroups for shaft tensile strength for a
for design verification testing can be appropriately selected by
device that contains two different shaft designs in the device
using one of the following approaches:
matrix, but the other EDOs that were identified (shaft material
5.5.1.1 Test each design subgroup,
and shaft bond design) are the same for the entire device
5.5.1.2 Test the worst-case design subgroup, or
matrix. Therefore, there is a design subgroup that is defined by
the device sizes that have shaft design “A” and a design 5.5.1.3 Test a subset of the design subgroups.
F3172−15 (2021)
FIG. 3Design Subgroups for Shaft Tensile (EDOs vary throughout the device matrix but are constant within each design subgroup)
FIG. 4Design Subgroups for Balloon Compliance (EDOs vary throughout the device matrix but are constant within each design sub-
group)
5.5.2 Test Each Design Subgroup: represents the entire device matrix, factors such as device sizes
5.5.2.1 Depending on the design subgroup definition, test-
used for other testing to minimize total test units or device size
ing each design subgroup may translate into testing one device
with the highest sales volume may be considered.
size or multiple device sizes to verify the entire device matrix.
5.5.2.3 Whenthedesignsubgroupsaredefinedbysubsetsof
5.5.2.2 When the design subgroup is defined by the entire
the device matrix, a device size should be selected from within
device matrix and the requirement is the same throughout the
each design subgroup to verify the design adequately since
device matrix, any device size may be selected for verification
EDOs vary throughout the device matrix. Fig. 6 illustrates the
testing to represent the entire device matrix. This approach is
design subgroups and example device sizes selected for veri-
appropriate since all device sizes share the same design for the
fication testing for shaft tensile strength. Note that the shaft
specified design input requirement (that is, the EDOs are the
tensile strength requirement is the same for all device sizes and
sameforalldevicesizes).Fig.5illustratesthedesignsubgroup
the other EDOs identified (shaft material and shaft bond
and example device size selection for verification testing for
design) are the same for all device sizes.
manifold connection/luer lockability. Since any device size
F3172−15 (2021)
FIG. 5Example Design Subgroup and Verification Device Size Selection for Manifold/Luer Lockability Testing
FIG. 6Example Design Subgroups and Verification Device Size Selection for Shaft Tensile Strength
FIG. 7Worst-Case Size May Be Selected Based on a Safety Factor Calculation
5.5.2.4 An alternate a
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