1、Designation: F3172 15Standard Guide forDesign Verification Device Size and Sample Size Selectionfor Endovascular Devices1This standard is issued under the fixed designation F3172; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides guidance for selecting an appropri-ate device size(s) and determining an appropriate samp
3、lesize(s) (that is, number of samples) for design verificationtesting of endovascular devices. A methodology is presented todetermine which device size(s) should be selected for testing toverify the device design adequately for each design inputrequirement (that is, test characteristic). Additionall
4、y, differentstatistical approaches are presented and discussed to help guidethe developer to determine and justify sample size(s) for thedesign input requirement being verified. Alternate methodolo-gies for determining device size selection and sample sizeselection may be acceptable for design verif
5、ication.1.2 This guide applies to physical design verification test-ing. This guide addresses in-vitro testing; in-vivo/animal stud-ies are outside the scope of this guide. This guide does notdirectly address design validation; however, the methodologiespresented may be applicable to in-vitro design
6、 validationtesting. Guidance for sampling related to computational simu-lation (for example, sensitivity analysis and tolerance analysis)is not provided. Guidance for using models, such as design ofexperiments (DOE), for design verification testing is notprovided. This guide does not address samplin
7、g across multiplemanufacturing lots as this is typically done as process valida-tion. Special considerations are to be given to certain tests suchas fatigue (see Practice E739) and shelf life testing (see Section8).1.3 Regulatory guidance may exist for endovascular devicesthat should be considered f
8、or design verification device sizeand sample size selection.1.4 UnitsThe values stated in SI units are to be regardedas the standard. No other units of measurement are included inthis standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. I
9、t is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E739 Practice for StatisticalAnalysis of Linear or LinearizedStress-Life (S-N)
10、and Strain-Life (-N) Fatigue DataF2914 Guide for Identification of Shelf-life Test Attributesfor Endovascular Devices2.2 ISO Standards:3ISO 14971:2012 Medical devicesApplication of risk man-agement to medical devices3. Terminology3.1 Definitions:3.1.1 attribute data, ndata that identify the presence
11、 orabsence of a characteristic (for example, good/bad or pass/fail).3.1.2 design input requirements, nphysical and perfor-mance requirements of a device that are used as a basis fordevice design (typically defined as test characteristics such asballoon burst pressure, shaft tensile strength, and so
12、forth).3.1.3 design output, nfeatures of the device (that is,dimensions, materials, and so forth) that define the design andmake it capable of achieving design input requirements.3.1.4 design subgroup, nset defined by the device sizeswithin the device matrix in which the essential design outputsdo n
13、ot vary for a specified design input requirement (that is,device sizes that share the same design for a specified designinput requirement).3.1.5 design validation, nestablishing by objective evi-dence that the device conforms to defined user needs andintended use(s).1This guide is under the jurisdic
14、tion of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.30 on Cardiovascular Standards.Current edition approved Dec. 15, 2015. Published February 2016. DOI:10.1520/F317215.2For referenced ASTM standards, visit the ASTM website, www.
15、astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ans
16、i.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.6 design verification, nconfirmation by examinationand provision of objective evidence that the device design(design output) fulfills the specified requirements (designinput).3
17、.1.7 device matrix, nentire range of available models/sizes for the device family.3.1.8 device size, nindividual model/size (for example, 6mm diameter by 25 mm length balloon on 135 cm lengthcatheter or a 6Fr 100 cm length guide catheter).3.1.9 endovascular device, ndevice used to treat vascularcond
18、itions from within the vessel.3.1.10 essential design output, EDO, ndesign feature(s) orcharacteristic(s) of the device that affects its ability to achievethe design input requirements (that is, design output(s) that hasa relevant effect on the test results).3.1.11 process validation, nestablishment
19、 by objectiveevidence that a process consistently produces a result or deviceachieving its predetermined requirements.3.1.12 safety factor, nratio of the device performance tothe specification requirement (for example, how much strongerthe device is than it needs to be to meet its specificationrequi
20、rement).3.1.13 sample size, nquantity of individual specimens of adevice tested.3.1.14 variables data, ndata that measure the numericalmagnitude of a characteristic (how good/how bad).4. Significance and Use4.1 The purpose of this guide is to provide guidance forselecting appropriate device size(s)
21、and determining appropri-ate sample size(s) for design verification of endovasculardevices. The device size(s) and sample size(s) for each designinput requirement should be determined before testing. Thedevice size(s) selected for verification testing should establishthat the entire device matrix is
22、 able to achieve the design inputrequirements. If testing is not performed on all device sizes,justification should be provided.4.2 The sample size justification and statistical proceduresused to analyze the data should be based on sound scientificprinciples and should be suitable for reaching a jus
23、tifiableconclusion. Insufficient sample size may lead to erroneousconclusions more often than desired.4.3 Guidance regarding methodologies for determining de-vice size selection and appropriate sample size is provided inSections 5 and 6.5. Selection of Device Size(s)5.1 Design input requirements are
24、 the physical and perfor-mance requirements of a device that are used as a basis fordevice design. Once the device design is defined, testing istypically performed to verify that the design input requirementsare met. The appropriate device size(s) for verification testingshould be determined for eac
25、h design input requirement.Testing the same device size(s) is typically not appropriate toverify all design input requirements. Differences in the devicedesign throughout the device matrix will drive which devicesize(s) is selected for verification of each design input require-ment.5.1.1 As explaine
26、d in subsequent sections, when determin-ing device size(s) for testing, the following should be consid-ered for each design input requirement:5.1.1.1 Essential design outputs,5.1.1.2 Design subgroups, and5.1.1.3 Other considerations.5.2 Define Essential Design Outputs (EDOs)The designoutputs of the
27、device are the features of the device (that is,dimensions, materials, and so forth) that define the design andmake it capable of achieving design input requirements. Not alldesign outputs are essential for each design input requirement.Therefore, for each design input requirement, the essentialdesig
28、n outputs (EDOs) should be identified. In Table 1,example EDOs for design input requirements of a ballooncatheter device are provided.5.3 Define Design Subgroups:5.3.1 The design subgroups should be defined for eachdesign input requirement based on the EDOs identified.5.3.2 For a specific design inp
29、ut requirement, the designsubgroups can be defined as one of the following:5.3.2.1 The entire device matrix if the EDOs for the designinput requirement are constant throughout the entire devicematrix,5.3.2.2 Subsets of the device matrix if the EDOs for thedesign input requirement vary in groups or s
30、tages throughoutthe device matrix, or5.3.2.3 Each individual device size of the device matrix ifEDOs for the design input requirement are different for eachindividual device size.5.3.3 Fig. 1 represents the device matrix (entire range ofavailable device sizes) for a 135 cm length balloon catheterdev
31、ice that has balloon diameters ranging from 3 to 7 mm andballoon lengths ranging from 10 to 50 mm. Balloon cathetersare available in any combination of balloon diameter andlength resulting in 25 unique device sizes in the device matrix.5.3.4 Figs. 2-4 illustrate how the device matrix in Fig. 1 isdef
32、ined by different design subgroups for different design inputrequirements. Fig. 2 represents a design subgroup that isdefined by the entire device matrix because all device sizesshare the same design for the specified design input require-ment (that is, the EDOs remain constant for all device sizes)
33、.TABLE 1 Example EDOs for Design Input Requirements for aBalloon Catheter DeviceDesign Input Requirement EDOsManifold connection/ Luer lockability Luer thread dimensionsManifold materialCatheter shaft tensile strength for asingle lumen catheterShaft materialShaft cross sectional area(diameter and wa
34、ll thickness)Shaft bond designBalloon compliance (diameter versuspressure)Balloon diameterBalloon materialBalloon wall thicknessBalloon deflation time Balloon volumeShaft deflation lumen designF3172 152The design input requirement is manifold connection/luerlockability testing, and the EDOs (luer th
35、read dimensions andmanifold material) are the same for all sizes in the devicematrix.5.3.5 Figs. 3 and 4 represent design subgroups that aresubsets of the device matrix because the EDOs for the designinput requirement vary throughout the device matrix. Fig. 3represents design subgroups for shaft ten
36、sile strength for adevice that contains two different shaft designs in the devicematrix, but the other EDOs that were identified (shaft materialand shaft bond design) are the same for the entire devicematrix. Therefore, there is a design subgroup that is defined bythe device sizes that have shaft de
37、sign “A” and a designsubgroup that is defined by the device sizes that have shaftdesign “B.” Fig. 4 represents design subgroups for ballooncompliance in which each balloon diameter defines a uniquedesign subgroup.5.4 Design Input Requirements and OtherConsiderationsIn addition to design subgroup def
38、inition,design input, device labeling, or regulatory requirements maymake it necessary to test additional sizes.5.5 Device Size Selection Approach:5.5.1 ApproachOnce the design subgroups are defined fora given design input requirement, the device size(s) to be testedfor design verification testing c
39、an be appropriately selected byusing one of the following approaches:5.5.1.1 Test each design subgroup,5.5.1.2 Test the worst-case design subgroup, or5.5.1.3 Test a subset of the design subgroups.5.5.2 Test Each Design Subgroup:5.5.2.1 Depending on the design subgroup definition, test-ing each desig
40、n subgroup may translate into testing one devicesize or multiple device sizes to verify the entire device matrix.FIG. 1 Device Matrix for a Balloon Catheter Device (25 Unique Device Sizes)FIG. 2 Design Subgroup for Manifold Connection/Luer Lockability Testing (EDOs Remain Constant throughout the Dev
41、ice Matrix)F3172 1535.5.2.2 When the design subgroup is defined by the entiredevice matrix and the requirement is the same throughout thedevice matrix, any device size may be selected for verificationtesting to represent the entire device matrix. This approach isappropriate since all device sizes sh
42、are the same design for thespecified design input requirement (that is, the EDOs are thesame for all device sizes). Fig. 5 illustrates the design subgroupand example device size selection for verification testing formanifold connection/luer lockability. Since any device sizerepresents the entire dev
43、ice matrix, factors such as device sizesused for other testing to minimize total test units or device sizewith the highest sales volume may be considered.5.5.2.3 When the design subgroups are defined by subsets ofthe device matrix, a device size should be selected from withineach design subgroup to
44、verify the design adequately sinceEDOs vary throughout the device matrix. Fig. 6 illustrates thedesign subgroups and example device sizes selected for veri-fication testing for shaft tensile strength. Note that the shafttensile strength requirement is the same for all device sizes andthe other EDOs
45、identified (shaft material and shaft bonddesign) are the same for all device sizes.5.5.2.4 An alternate approach to selecting one device size torepresent each design subgroup would be to pool multiple sizeswithin a design subgroup for testing. Refer to Section 7 formore information on data pooling.5
46、.5.3 Test the Worst-Case Design Subgroup:5.5.3.1 For certain design input requirements, testing onlythe worst-case design subgroup adequately verifies the entiredevice matrix. The worst-case design subgroup is determinedby considering how the EDOs impact performance to theFIG. 3 Design Subgroups for
47、 Shaft Tensile (EDOs Vary throughout the Device Matrix But Are Constant within Each Design Subgroup)FIG. 4 Design Subgroups for Balloon Compliance (EDOs Vary throughout the Device Matrix But Are Constant within Each Design Sub-group)F3172 154design input requirements. If the design input requirement
48、 limitvaries throughout the device matrix for example, differentrated burst pressure (RBP) requirements for different diameterballoon catheters, a worst case could be tested for eachspecification limit or one worst-case subgroup could be testedby performing a worst-case analysis that accounts for th
49、edifferences in the specification limits, such as a safety factorcalculation. Additionally, if the design input requirement hasboth an upper and a lower specification limit, there may be aworst case for the upper specification and a different worst casefor the lower specification.5.5.3.2 Testing the worst-case design subgroup is a com-monly used verification method when EDOs vary throughoutthe device matrix and their impact to the design input perfor-mance is well understood/defined (for example, increasingdiameter has a negative impact on achieving the des
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