1、Designation: F 1828 97 (Reapproved 2006)Standard Specification forUreteral Stents1This standard is issued under the fixed designation F 1828; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe objective of this specification is to describe the test methods used to evaluate the safety andeffectiveness of an indwelling ureteral stent,
3、having retention means at the kidney and bladder ends,used for urinary drainage of the kidney to the bladder via the ureter.This specification includes referee test methods that can be used to evaluate the performancecharacteristics of ureteral stents. Note that the test methods are not to be constr
4、ued as productionmethods, quality control techniques, or manufacturers lot release criteria. The product parametersaddressed by the standard include those determined by the ASTM task group to be pertinent to theproduct.1. Scope1.1 This specification covers the referee test methods forevaluating the
5、performance characteristics of a single-useureteral stent with retaining means at both ends, during shortterm use for drainage of urine from the kidney to the bladder.These stents are typically available in diameters of 3.7 Fr to14.0 Fr, and lengths of 8 cm to 30 cm, and are made of silicone,polyure
6、thane, and other polymers. They are provided non-sterile for sterilization and sterile for single-use.1.2 ExclusionsLong-term indwelling usage (over 30days) is encountered with this product, but not commonly, andis therefore considered an exception to this specification.Similarly, the use of uretera
7、l stents for non-ureteral applica-tions such as nephrostomy and ileostomy is excluded from thescope of this specification. Non-sterile ureteral stents are alsoexcluded due to the variability of hospital sterilization equip-ment and processes and the resulting effects on ureteral stentcharacteristics
8、.1.3 The following precautionary statement pertains only tothe test method portion, Section 5, of this specification:1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priat
9、e safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 412 Test Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionF 640 Test Methods for Radiopacity of Plastics for MedicalUseF 748 Practice fo
10、r Selecting Generic Biological Test Meth-ods for Materials and Devices3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 artificial urinea solution of organic and inorganiccompounds that closely simulates the chemical and physicalproperties of normal human urine. Artificial urine
11、 will be usedas a substitute for human urine to simulate the effects of humanurine on ureteral stents.3.1.2 bladder retention meansphysical feature of bladderend of stent the prevents movement of stent out of bladder.3.1.3 break strengthpeak tensile load required to breakstent.3.1.4 cross sectionvie
12、w of stent tube when cut in a planeperpendicular to length of stent.3.1.5 distalsituated away from the point of origin. Thedistal end of a stent is the end that resides in the bladder, alsoknown as the bladder end.3.1.6 drainage holesholes in wall of stent tubing thatallow flow of urine into and out
13、 of lumen of stent.1This specification is under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.34 on Urological Materials and Devices.Current edition approved March 1, 2006. Published April 2006. Originallyappro
14、ved in 1997. Last previous edition approved in 1997 as F 1828 97.2For referenced ASTM standards, visit the ASTM website, www.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 webs
15、ite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 dynamic frictional forceresistance to relative mo-tion between two surfaces during motion. This force is definedas the coefficient of kinetic friction multiplied by the forcea
16、cting on the surface of the material in a plane perpendicular tothe surface.3.1.8 elongationexpressed as a percent, is equal to thechange in length of a sample of tubing at failure divided by itsoriginal length. Stretching of the tubing is produced by tensileloading.3.1.9 French sizeScale used to in
17、dicate size of tubulardevices, each unit being approximately equal to 0.013 in. or0.33 mm in diameter. Typical label French sizes are as follows:French Size Outside Diameterin. mm3.7 0.050,1.234.5 0.060,1.504.7 0.061,1.576.0 0.079,2.007.0 0.092,2.338.0 0.105,2.678.5 0.112,2.8310.0 0.131,3.3314.0 0.1
18、83,4.663.1.10 kidney retention meansphysical feature of kidneyend of stent that prevents movement of stent out of the kidney.3.1.11 lengthlength of stent is defined as the distancebetween the most proximal portion of the bladder retentionmeans and the most distal portion of the kidney retentionmeans
19、 when the stent is laying on a flat surface with themainshaft straight. (See Fig. 1).3.1.12 lumenthe channel within a tube.3.1.13 proximalsituated toward the point of origin. In theurinary tract, the kidney is considered to be the point of origin.The proximal end of a stent is the end that resides i
20、n the renalpelvis, also known as the kidney end.3.1.14 radiopacityproperty indicating ability of device toabsorb x-ray energy, allowing device to be seen in a radiographor fluoroscopic screen.3.1.15 referee test methodthe method cited in the pub-lished specification for the device. This method will
21、be usedwhen the performance of the ureteral stent is to be evaluated.The manufacturer need not use this referee test method forinspection and quality control.3.1.16 retention strengthforce required to overcome theretaining means on a stent.3.1.17 sterilitythe state of being free of microorganisms.Fo
22、r purposes of this specification, sterility is defined asfreedom from microorganisms when tested according to themethodology defined by the USP for nonparenteral devices.3.1.18 tolerancesthe allowable deviation from a standardsize. The tolerance for the length of a ureteral stent is 60.5 cm(0.197 in
23、). the tolerance for the specified French size of aureteral stent is 60.01 mm (0.004 in), or approximately13French.3.1.19 ureteral stentan indwelling tubular device thatresides in the kidney, ureter, and bladder containing means forretaining ends of tube in kidney and bladder.4. Requirements4.1 Bioc
24、ompatibility Ureteral stents shall be tested inaccordance with the appropriate biological tests contained inSpecification F 748 or similar guidance established by the U. S.Food and Drug Administration or International Organizationfor Standardization (ISO).5. Special Precautions5.1 The following caut
25、ionary comments recognize the sen-sitivity of the materials of construction to potential environ-mental conditions. These are outlined here to point out poten-tial situations that could adversely affect the performance of thestent during testing.5.1.1 Care should be taken during testing and use to p
26、reventdamage to the stents. Such damage can be caused by abrasionand contact with sharp objects or chemical products.5.1.2 Stents should be kept away from generators, electricmotors, diathermy machines, and fluorescent lights because theozone produced may attack elastomeric materials. This appliesto
27、 both storage and handling.5.1.3 To help avoid contamination of the stents properhandling precautions should be observed.6. Test Methods6.1 General Guidelines:6.1.1 Test samples should consist of actual ureteral stents,not material slabs.FIG. 1 Determine of Stent LengthF 1828 97 (2006)26.1.2 Use sta
28、tistically valid sample sizes in all tests.6.1.3 Package all stent test samples and sterilize once usingthe method of sterilization intended to be used for productwhen it is sold.6.1.4 Expose test samples to artificial urine at 37 6 3 C fora period of 30 days. Use either of the two artificial urinef
29、ormulations listed in Annex A1. In situations where testing inartificial urine is not practical, distilled water may be used.6.1.5 Maintain artificial urine pH in the range of 5.5 to 6.5at all times. Replace urine should be weekly.6.1.6 Perform tests prior to and after soaking for a minimumof 30 day
30、s. For products with intended chemical/mechanicalchanges such as softening, swelling, etc., do initial mechanicaltesting only after sufficient soaking time has elapsed that allowsuch chemical/mechanical changes to occur.6.1.7 Dynamic frictional force test samples need only besoaked in distilled wate
31、r for 1 min prior to testing. This test willnot be repeated after 30 days.6.2 Retention Strength:6.2.1 ScopeThis test method measured the ability of aureteral stent to resist migration. It can be used for testing theproximal or distal ends of a ureteral stent.6.2.2 Summary of Test Method:6.2.2.1 The
32、 apparatus is set up as shown in Fig. 2. Clearancebetween the outside diameter of the stent and inside diameterof the funnel block hole must be present. (See Note 1 in Fig. 2for a list of appropriate funnel block hole diameters to be usedwith stents of different French sizes.)6.2.2.2 Maintain temper
33、ature in the water bath at 37 6 3Cby whatever means is available to the test facility. Submergethe entire funnel block. Set the pull rate through the fixture ata constant 20 in.(mm)/min. Clean the test bath and fixture at thebeginning of each testing day. The capacity of the load cellused with the t
34、ensile testing machine should not exceed 2 lb.6.2.3 Test Specimen PreparationThe test specimen shallconsist of actual sterilized product. The specimen shall be cutto allow a straight portion of the stent to be inserted upwardsthrough the funnel fixture into the grip of the tensile testmachine withou
35、t loading the retention mechanism of the stentto be tested. Submerge the test specimen in the water bath forat least 1 min to allow it to reach thermal equilibrium. If thematerial is significantly affected by moisture, allow the speci-men to equilibrate for a minimum of 24 h. Use distilled water,if
36、possible.NOTE 1The portion of the stent held within the gripping mechanismof the tensile testing machine cannot be used for additional testing due tothe potential destructive effects of the gripping mechanism.6.2.4 Test Procedure:6.2.4.1 Ensure test bath is at proper temperature and funnelis submerg
37、ed. Monitor periodically.6.2.4.2 When testing a new ureteral stent taken out of itssterile package, (t=0), straighten retention means with appro-priate guidewire. Insert straight portion of stent through bottomof funnel and into grip. When testing at t=30 days, retentionmeans is not to be straighten
38、ed prior to testing.FIG. 2 Funnel Block for Retention Strength TestF 1828 97 (2006)36.2.4.3 Allow stent to reach thermal equilibrium.6.2.4.4 Pull specimen up through funnel at 20 in./min.Record maximum force required to pull stent completelythrough funnel.6.3 Break Strength:6.3.1 Break strengths of
39、test stents will be determined inaccordance with Test Method D 412, with the followingmodifications:6.3.1.1 Devices used to grip the test specimen in the tensiletest machine should be chosen so that the test specimen doesnot break at the grip location.6.3.1.2 Most stents contain drainage holes. Idea
40、lly, thesestents should break at a drainage hole. This is how tensilefailures typically occur in vivo. However, stents may break inlocations other than drainage holes. This type of failure may beindicative of potential design or process related problems. Instents without drainage holes, this type of
41、 failure is to beexpected.6.3.1.3 Only a segment of the test stent is used for the breakstrength test. The grippers should be separated by 1 in. This 1in. segment must contain at least one drainage hole (if drainageholes are present) and should contain the section of the stentwith the smallest cross
42、 sectional area or weakest point.6.4 ElongationThe elongation of stent segments sepa-rated by 1 in. between the extensometer grips used to hold thesegment in the tensile test machine or two marks placed on thesurface of the stent will be determined in accordance with TestMethod D 412.6.5 Dynamic Fri
43、ctional Force(Required for Support ofClaims of Low Friction):6.5.1 ScopeThis test method measures the dynamic fric-tional force acting upon the outer surface of ureteral stentduring placement through a small orifice. This test method isintended to simulate passage ofa6Frureteral stent through anendo
44、scope.6.5.2 Summary of Test MethodStraighten the test stentusing a wire mandrel and hydrated in a cylinder of distilledwater. Then place it completely through the appropriate sizegrommet and into a water column. The mandrel is connected toa load cell that is pulled at constant rate of 20 in/min. Rec
45、ordthe force values measured by the load cell on a chart recorderor minicomputer and average to determine the dynamic fric-tional force.6.5.3 Test Set-Up(See Fig. 3.)6.5.3.1 Cylindercapable of hydrating the full length of theureteral stent sample.FIG. 3 Test Apparatus for dynamic Frictional Force Te
46、stF 1828 97 (2006)46.5.3.2 Water Columnused to hydrate the full length ofthe test stent prior to passage through grommet.6.5.3.3 Distilled Waterused to hydrate the test stent (andactivate any hydrophilic coating present) at room temperature.6.5.3.4 GrommetA 0.040 6 0.002 in. thick, 5/8 in. diam-eter
47、 disc, with a 0.079 6 0.002 in. ( 6 mm.) diameter hole inthe center. The grommet is to be made of 55 Shore ADurometer silicone.6.5.3.5 Grommet FixtureThe grommet is held in place bytwo aluminum plates containing relief holes approximately18in. larger is diameter than the hole in the grommet. Whenmou
48、nted, the hole in the grommet should be centered about therelief hole in the aluminum plates.6.5.3.6 Load CellLoad cell capacity should not exceed 1lb, and should be capable of measuring the frictional forcewithin 65 % of its value.6.5.3.7 Linear Tableused to pull the load cell at a constantrate. A
49、linear table will not be necessary if a standard tensiletest machine is used.6.5.3.8 MandrelA mandrel large enough to straighten andhold the test stent during the test is used. An eyelet is used onone end to attach to the load cell.6.5.4 Precautions:6.5.4.1 Follow all proper safety precautions.6.5.4.2 Take care prior to and during testing not to causedamage to the test stent or grommet. Avoid contact with sharpor abrasive objects and any solvents that may damage thematerials.6.5.4.3 Use fresh distilled water to limit the accumulation ofb
