AAMI-TIR17-1997.pdf
Technical Information Report AAMI TIR17:1997 AAMI Association for the Advancement of Medical Instrumentation Radiation sterilization Material qualification Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- AAMI TIR No. 171997 Radiation sterilizationMaterial qualification Approved 4 August 1997 Abstract:This AAMI Technical Information Report (TIR) details steps necessary to assess compatibility of health care product and packaging materials with radiation sterilization processes. Guidance is provided on selecting appropriate materials, choosing processing protocols that optimize product performance, and material testing as part of a qualification program. An extensive review of accelerated aging techniques is also included. Companion document to ANSI/AAMI/ISO 11137:1994. Keywords:sterilization, radiation, material qualification, accelerated aging, health care products, real time aging Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- Published by Association for the Advancement of Medical Instrumentation 1110 N. Glebe Road, Suite 220 Arlington, VA 22201-5762 © 1998 by the Association for the Advancement of Medical Instrumentation All Rights Reserved This publication is subject to copyright claims of AAMI. No part of this publication may be reproduced or distributed in any form, including an electronic retrieval system, without the prior written permission of AAMI. All requests pertaining to this draft should be submitted to AAMI. It is illegal under federal law (17 U.S.C. § 101, et seq.) to make copies of all or any part of this document (whether internally or externally) without the prior written permission of the Association for the Advancement of Medical Instrumentation. Violators risk legal action, including civil and criminal penalties, and damages of $100,000 per offense. For permission regarding the use of all or any part of this document, contact Kurt C. Larrick, Director, Technical Publishing, at AAMI, 1110 N. Glebe Road, Suite 220, Arlington, VA 22201. Phone: (703) 525-4890, Ext. 239; Fax: (703) 525-1067. Printed in the United States of America ISBN 1-57020-107-2 Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- AAMI TECHNICAL INFORMATION REPORT A technical information report (TIR) is a publication of the Association for the Advancement of Medical Instrumentation (AAMI) Standards Board that addresses a particular aspect of medical technology. Although the material presented in a TIR may need further evaluation by experts, there is value in releasing the information because of the immediate need for it by the industry and the professions. A TIR differs markedly from a standard or recommended practice, and readers should understand the differences between these documents. Standards and recommended practices are subject to a formal process of committee approval, public review, and resolution of all comments. This process of consensus is supervised by the AAMI Standards Board and, in the case of American National Standards, the American National Standards Institute. A TIR is not subject to the same formal approval process as a standard. However, a TIR is approved for distribution by a technical committee and the AAMI Standards Board. Another difference is that, although both standards and TIRs are periodically reviewed, a standard must be acted uponreaffirmed, revised, or withdrawnand the action formally approved usually every 5 years but at least every 10 years. For a TIR, AAMI consults with a technical committee about 5 years after the publication date (and periodically thereafter) for guidance on whether the document is still usefulthat is, to check that the information is relevant or of historical value. If the information is not useful, the TIR is removed from circulation. A TIR may be developed because it is more responsive to underlying safety or performance issues than a standard or recommended practice or because achieving consensus is extremely difficult or unlikely. Unlike a standard, a TIR permits the inclusion of differing viewpoints on technical issues. CAUTION NOTICE: This AAMI Technical Information Report may be revised or withdrawn at any time. Because it addresses a rapidly evolving field or technology, readers are cautioned to ensure that they have also considered information that may be more recent than this document. Comments on this technical information report are invited and should be sent to AAMI Standards Program, 3330 Washington Boulevard, Suite 400, Arlington, VA 22201-4598. Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- CONTENTS Page Committee representation.vii Forewordix Introduction.x 1Scope1 2Normative references.1 3Definitions, symbols, and abbreviations .2 3.1Aging definitions.2 3.2Statistical definitions.3 3.3Miscellaneous definitions 3 4Material selection4 4.1Functional compatibility4 4.2Biocompatibility9 5Material processing .10 5.1Polymer processing overview.10 5.2Impact of processing versus impact of radiation.10 6Material testing 12 6.1Definition of functional requirements.12 6.2Definition of challenge tests and acceptance criteria.13 7Accelerated aging programs.15 7.1Introduction15 7.2Characterization of materials.16 7.3Defining an aging factor for related products.17 7.4Aging factor (AF) estimates 17 7.5Aging programs19 7.6Alternative aging methodologies26 7.7Biocompatibility considerations.26 Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- Annexes AMaterial radiation compatibility fundamentals27 BMaterial processing and product design guidelines29 CAccelerated aging theory31 DWorked example of fixed aging factor method32 EWorked example of iterative aging factor method.35 FBibliography42 Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- © 1998 Association for the Advancement of Medical Instrumentationvii COMMITTEE REPRESENTATION This Technical Information Report (TIR) was developed by the Radiation Sterilization Working Group of the AAMI Sterilization Standards Committee. Committee approval of the TIR does not necessarily imply that all committee and working group members voted for its approval. The AAMI Sterilization Standards Committee has the following members: Cochairs:William E. Young Virginia C. Chamberlain, PhD Members:Carl W. Bruch, PhD, Consultant, Hudson, WI Virginia C. Chamberlain, PhD, Consultant, Hendersonville, NC Neal E. Danielson, Pennsylvania Engineering Company, Wichita, KS Judith C. Dowler, Medical Devices Bureau, Health Canada, Ottawa, ON Frank B. Engley, Jr., PhD, Univ. Missouri School of Medicine, Columbia, MO Victoria Hitchins, PhD, FDA/CDRH, Rockville, MD Robert F. Morrissey, PhD, Johnson to avoid processing errors that can contribute to negative effects from radiation sterilization (see 5). c)Testingchallenging critical aspects of the product for functionality and safety after sterilization and aging (see 6). d)Accelerated agingapplying accelerated aging programs that ensure correlation with real time aging while reducing the cost and amount of time required for material qualifications (see 7). 2Normative references The following standards contain provisions, which, through reference in this text, constitute provisions of this TIR. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this TIR are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. ANSI/AAMI/ISO 111371994, Sterilization of health care productsRequirements for validation and routine controlRadiation sterilization. ANSI/AAMI/ISO 116071997, Packaging for terminally sterilized products. ANSI/AAMI 10993-11994, Biological evaluation of medical devicesPart 1: Evaluation and testing. ISO/DIS 14538, Method for the establishment of allowable limits for residues in medical devices using health based risk assessment. (in development) ISO/TR 8550:1994, Guide for the selection of an acceptance sampling system, scheme or plan for inspection of discrete items in lots. Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- 2© 1998 Association for the Advancement of Medical Instrumentation 3Definitions, symbols, and abbreviations For the purposes of this TIR, the following definitions and abbreviations related to aging apply. 3.1Aging definitions 3.1.1 real time aging (RT): Storage of health care products at ambient conditions in order to evaluate functional properties over time. 3.1.2 accelerated aging (AA): Storage of health care products at elevated temperatures and/or at other intensified environmental conditions in order to simulate real time aging in a shorter amount of time. 3.1.3 T: Symbolizes temperature, measured in degrees Celsius, utilized in aging studies. NOTETRT and TAA symbolize real time and accelerated aging temperatures, respectively. 3,1,4 t: Symbolizes time, over which aging studies are conducted. NOTEtRT and tAA symbolize the storage time over which real time and accelerated aging studies have been conducted. 3.1.5 real time equivalent (RTE): Amount of real time to which given accelerated aging conditions are estimated to be equivalent. NOTEFor example, if AA samples are held at an elevated temperature for 6 months and the aging factor (AF0) for the system has been estimated to be 2, then the RTE is 1 year: RTE= tAA x AF0 = 6 months x 2 = 1 year. 3.1.6 time zero (t0): Starting time of any timed investigation, experiment, or study. NOTEIn this TIR, t0 is the time of commencement of an aging study. 3.1.7 aging factor (AF): Ratio of time between TRT and TAA that is estimated or calculated to achieve the same level of functional degradation of the health care product in real time as that observed under accelerated aging. 3.1.7.1 AF0: Initial estimate of AF. NOTEFor example, AF0 = 23 = 8 is commonly used when a temperature 30° C higher than ambient is used for the accelerated aging study (based on a Q10 = 2see Q10 definition). 3.1.7.2 AF1: First iteration of AF0 based on initial real time data. 3.1.7.3 AF2, AF3, etc.: Subsequent iterations of AF0 based on additional real time data. 3.1.8 Q10: Symbol used to express the expected or observed change in the rate of a reaction occasioned by a 10° C change in reaction thermal environment. NOTEQ10 = 2 is a common and conservative estimate for most polymer systems. Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,-,- © 1998 Association for the Advancement of Medical Instrumentation3 3.1.9 S: Symbolizes the slope of the plot of the aging curve for chosen parameters under study. Thus S(RT), S(AA), and S(RTE) are the slopes of real time, accelerated aging, and real time equivalent (i.e., accelerated aging data modified by the aging factor) curves, respectively. 3.1.10 shelf life: Length of time that a product can remain at the typical storage conditions prior to use without having an unacceptable effect on its functionality and biocompatibility or the length of time chosen for its expiration. 3.2 Statistical definitions 3.2.1 variable data: Data that have a numerical value (not attribute data). 3.2.2 attribute data: Pass/fail data; go/no go data NOTENo numerical value is associated with the data. 3.3 Miscellaneous definitions 3.3.1 materials qualification dose (DQUAL): Maximum radiation dose at which the functional integrity of the health care product or its components has been demonstrated. 3.3.2 Tm, Tg: Melt temperature and glass temperature, respectively; two common thermal transitions of polymeric materials. 3.3.3 absorbed dose: Quantity of radiation energy imparted per unit mass of matter. NOTEThe unit of absorbed dose is the gray (Gy) where 1 gray is equivalent to absorption of 1 joule per kilogram. 3.3.4 dose: See absorbed dose. 3.3.5 material biocompatibility: Lack of an adverse health effect from exposure to materials from which a device is made or in which a device is packaged. 3.3.6 functionality: Performance of a product from the perspective of its physical properties, rather than the perspective of biocompatibility. 3.3.7 health care product: Term encompassing medical devices, medicinal products (pharmaceuticals and biologics) and in vitro diagnostics. NOTEIn this document, the term health care product, or product, refers to the finished medical device and/or additional components with the final package. Copyright Association for the Advancement of Medical Instrumentation Provided by IHS under license with AAMI Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/21/2007 02:52:02 MDTNo reproduction or networking permitted without license from IHS -,
