1、Designation: F 2392 04Standard Test Method forBurst Strength of Surgical Sealants1This standard is issued under the fixed designation F 2392; 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.1. Scope1.1 This test method provides a means for comparison of theburst or rupture strength of sealants on soft tissue. This testmethod can be used as a clin
3、ically relevant model for qualityassurance, development, and comparative testing of differentadhesives or adherends.1.2 This test method measures only burst strength or “co-hesive strength” of an adhesive/adherend system, and not theadhesive strength.1.3 This standard does not purport to address all
4、 of thesafety concerns, if any, associated with its use. It 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:2D 907 Terminology of
5、Adhesives2.2 American Association for Tissue Banks (AATB) Stan-dard:Standards for Tissue Banking33. Terminology3.1 DefinitionsMany terms in this test method are definedin Terminology D 907.3.2 Definitions:3.2.1 adhesive failurefailure of the sealant/substrate inter-face during burst testing.3.2.2 bu
6、rst strengththe average pressure required to causefailure of the sealant, either by cohesive or adhesive mecha-nisms.3.2.3 cohesive failurefailure of the sealant during bursttesting.3.2.4 cohesive strengththe internal strength of the sealant,sometimes referred to as the adhesive bulk strength.3.2.5
7、substrate failurefailure of the substrate during bursttesting.3.2.6 tissue sealanta surface coating to prevent leakage ofbody fluids.4. Significance and Use4.1 Materials and devices that function at least in part byadhering to living tissues are finding increasing use in surgicalprocedures, either a
8、s adjuncts to sutures and staples or as frankreplacements for those devices in a wide variety of medicalprocedures. While the nature and magnitude of the forcesinvolved varies greatly with indication and with patient specificcircumstances, all uses involve, to some extent, the ability ofthe material
9、 to resist imposed mechanical forces. Therefore, themechanical properties of the materials, and in particular theadhesive and cohesive properties, are important parameters inevaluating their fitness for use. In addition, the mechanicalproperties of a given sealant composition can provide a usefulmea
10、ns of determining product consistency for quality control,or as a means for determining the effects of various surfacetreatments on the substrate prior to use of the device.4.2 The complexity and variety of individual applicationsfor sealant, even within a single indicated use (surgicalprocedure), i
11、s such that the results of a burst test are notsuitable for determining allowable design stresses withoutthorough analysis and understanding of the application andsealant behaviors.4.3 This test method may be used for comparing sealants forsusceptibility to environmental changes, but such comparison
12、smust be made with great caution since different sealants mayrespond differently to varying conditions.4.4 As the true sealant strength is strongly dependent on thestrength of the sealant/substrate interface, the selection of aproper test substrate is critical. Care must be taken whenextrapolating i
13、n vitro test results to in vivo expectations. Invitro sealant optimization may not translate to expected in vivoperformance due to differences in substrate surface, strength,and elasticity.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices
14、and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved May 1, 2004. Published June 2004.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association for Tissue Banks (AATB), 1320 OldChain Bridge Rd., Suite 450, McLean, VA 22101.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
16、 States.5. Apparatus5.1 Testing MachineA testing machine for determiningthe sealant strength and system failure mechanism and com-prising essentially the following:5.1.1 Test FixtureA stationary fixture containing the testsubstrate and applied sealant. Fluid flows into the fixture at afixed rate, al
17、lowing for the pressurization of the sealed sub-strate.5.1.2 Positive Displacement Fluid PumpA pump provid-ing a constant flow of fluid to the test fixture. The pump mustbe capable of constant flow at pressures of interest. Syringepumps are particularly well suited for this type of testing sincethey
18、 do not cause pulsatile flow. Peristaltic pumps have alsobeen used successfully since the pump tubing tends to dampenpulsations.NOTE 1Saline is the typical fluid of choice. When air is used, areduction in pressurization rate is expected due to gas compressibility.5.1.3 Pressure gageConsisting of a g
19、age and method ofcapturing peak pressures. System sampling rate should beadequate to capture peak burst pressures. Sensitivity andprecision should result in less than 1 % error. The burst testFIG. 1 Burst Test System (A), with an Exploded View of the Assembled Test Fixture (B),and the Test Fixture C
20、ross Sectional View (in.) (C)F2392042system is shown in Fig. 1. The system (A) consists of a fluidpump, a test fixture, and pressure gage connected by rigidplastic tubing. The test fixture (B) consists of a base, O-ring,and top.5.2 Temperature-controlling EquipmentMust be capableof maintaining the t
21、est temperature to 62C. If ambientlaboratory conditions are employed, the same degree of controlis required. A water bath or environmental chamber capable ofmaintaining 37C is required for testing on tissue substrates.6. Test Substrate6.1 For Comparative TestingCollagen sausage casing,Nippi Casing C
22、o. (#320),4should be used. It is a collagencasing of consistent properties and thickness.6.2 Cut sections off of the collagen casing roll, wash indeionized water (to remove glycerin), then soak in freshdeionized water for five minutes.6.3 Application Specific TestingSince the fixture mustclamp down
23、on the substrate to prevent fluid leakage, sometissues (lung, liver, and so forth) may not be suitable for thistest.6.3.1 The burst strength of any sealant is dependant on itsinternal cohesive strength, as well as the adhesive strength tothe test substrate, or adherend. For a specific application, t
24、hepreferred substrate is freshly harvested tissue from the targetorgan of a domestic food animal. Tissue from bovine, porcine,or ovine origin is preferred due to wide availability and the factthat relatively large samples of tissue can be harvested from asingle source. Ideally, the tissue should be
25、used within 24 h ofharvest and should be kept between 5 and 10C prior to testingif it cannot be used immediately after harvesting. Storage andhandling of tissue samples should be carried out according tothe guidelines set forth in Standards for Tissue Banking by theAmerican Association of Tissue Ban
26、ks. The specimens shouldbe brought to the test temperature or other prescribed tempera-ture (such as body temperature) prior to application of thesealant.6.3.2 Fixed tissue should not be used since it has beendemonstrated that fixatives cause large alterations in themechanical properties of the tiss
27、ue and it is probable that theadhesive strength would be affected as well.6.3.3 If the target organ is of a size or geometry, or both, thatdoes not allow fabrication of test samples, a tissue of similarorigin but larger size should be used.6.3.4 The thickness of the tissue sample should be mini-mize
28、d and should not exceed 5 mm. Thicker samples will leadto distortion of the substrate and may leak in the test fixture.Also, thicker samples will lead to sealant adherence on theinsides of the hole itself, possibly leading to different failuremechanisms. It is also important that the thickness be as
29、uniform as possible.6.4 Substrates for Quality Control Testing:6.4.1 For testing that is undertaken as part of a qualitycontrol process in the manufacturing of a tissue sealant, the useof freshly harvested tissue is highly inconvenient and may alsolead to unacceptable variation in the test results,
30、especially ifthe failure occurs in the adherend (substrate failure). Since thepurpose of quality control testing is to demonstrate consistencyin the device, substitution of a model substrate is preferred solong as it is demonstrated that the sealant does bond to theadherend. Since the burst test fai
31、lure mechanism can depend onthe amount of substrate deformation, attention to substrateflexibility and elasticity is important to best match in vivosubstrates.7. Substrate Preparation7.1 Cut substrate into circles (3.0 6 0.1 cm diameter) usinga sharp scalpel or stamp.7.2 Use a hole punch to create a
32、 3.0 mm diameter hole in thecenter of the circular substrate.NOTE 2Depending on the application, different hole sizes, cuts, orsuture lines may be used. Store in saline at room temperature until readyto use if testing will be done within1hofpreparation. Prepared substratemay be stored in saline in a
33、 refrigerator for up to 48 h.7.3 Number of Test SpecimensTest at least 10 specimensof each type. Burst testing tends to give high variances and willrequire more samples to attain a reasonable estimate of themean strength. The actual number of test samples tested willdepend on data variance.8. Sample
34、 Preparation8.1 Tissue Preparation:8.1.1 Place substrate on a polytetrafluoroethylene (PTFE)sheet and smooth out.8.1.2 Pat substrate using surgical gauze to remove excesswater.8.1.3 Place an approximately 1.0 mm thick PTFE mask ontop of the substrate, centering the 15 mm hole in the mask overthe hol
35、e in the substrate as shown in Fig. 2.8.2 Sealant Application:8.2.1 Assemble the applicator and prepare the tissue sealantas directed for the product being tested. Use appropriate tip.8.2.2 Apply the sealant per the instructions for use (IFU) inquantities sufficient to fill the hole in the PTFE mask
36、. Recordthe volume of adhesive used.NOTE 3Thickness is a very important parameter to control. Variablethickness will lead to greater burst strength variation.NOTE 4Low viscosity sealants may flow through the 3 mm hole andunder the substrate during this procedure. This may be prevented byplacing a th
37、in layer of petroleum jelly between the PTFE and substrate.8.2.3 Allow the adhesive to cure per the IFU.8.2.4 Lightly run an aluminum spatula around the edges ofthe sample to release from the mold.8.2.5 Peel the substrate off the PTFE block, being carefulnot to tear the tear the tissue sealant.8.2.6
38、 Samples tested more than 5 min after sealant applica-tion should be covered with gauze soaked in saline and storedat the conditioning temperature (see 9.1).9. Test Procedure9.1 Condition the test specimens for definite periods of timeunder specified, controlled conditions before testing if desired.
39、Recommended conditions for tissue sealants intended for4Nippi sausage casing (#320) is widely available throughout the meat packingindustry.F2392043internal applications are 37 6 1C in phosphate bufferedsaline. For quality control testing the recommended conditionsare 23 6 2C and 50 6 5 % relative h
40、umidity.9.2 After conditioning, it is recommended that all speci-mens be stabilized at the test temperature for 15 min beforetesting if the test temperature is different from the conditioningtemperature. Tissue samples must be kept moist throughout theprocess to prevent shrinkage due to drying. For
41、comparativetesting the test conditions should be 23 6 2C and 50 6 5%relative humidity (see Appendix X1).9.3 Test Fixture Assembly:9.3.1 Open the purge valve and turn on the fluid pump, thuspriming the test fixture with saline to eliminate air from thefluid line.9.3.2 Turn off the pump, and then plac
42、e the substrate withtissue sealant onto the fixture base, with the sealant facing up.Place the O-ring (22 mm ID) on top of the tissue, and securethe fixture top in place.9.4 Zero the pressure gage, and set to capture the peakpressure.9.5 Advance saline into the test fixture by turning the fluidpump
43、on at a flow rate of 2 mL/min. Close the purge valve afterflow is established and all air has been purged from the lines.9.6 Record the peak pressure, and the type of failure(cohesive, adhesive, or substrate) based on observation of theburst test.10. Calculation10.1 Calculate the average and standar
44、d deviation of burststrength for each group of samples.11. Report11.1 Report the following:11.1.1 Complete identification of the sealant tested, includ-ing type, source, date manufactured, manufacturers codenumber, and lot number.11.1.2 Complete identification of the substrate used, itsthickness, an
45、d any method used to clean or prepare the surfaceprior to bonding.11.1.3 Estimated amount of sealant applied.11.1.4 Method of sealant application.11.1.5 Ambient conditions at time of bonding (temperature,humidity, and so forth).11.1.6 Average thickness of the sealant.11.1.7 Conditioning of specimen
46、after application and priorto testing.11.1.8 Maximum, minimum, mean, and standard deviationof the burst strength for the group of specimens.11.1.9 Number of specimens tested.11.1.10 Type of failure.11.1.11 Test temperature and humidity employed.12. Precision and Bias12.1 A precision and bias stateme
47、nt does not exist for thistest method because round-robin testing has not yet beenperformed.13. Keywords13.1 adhesive strength; burst strength; cohesive strength;tissue sealantThickness = 1 6 0.5 mmFIG. 2 PTFE Mask for Adhesive ApplicationF2392044APPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 A
48、s with all mechanical testing, the temperature andhumidity can have a large effect on the results obtained usingthis procedure. Ideally, all of the testing will be carried out atthe intended use temperature (37C for internal applications),and at a constant relative humidity. However, the equipmentre
49、quired for environmental control is not available in alllaboratories. Furthermore, attempting to test samples immedi-ately after removal from the conditioning bath would lead tounacceptable variation in sample temperature at the time offailure. Therefore it was decided to allow the samples to coolto room temperature for 15 to 20 min prior to testing toeliminate that source of variability.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are
