Systems Theoretic Accident Model and Process Application: Quality Control in Medical Device ...

103 Pages·2014·7.78 MB·English

Systems Theoretic Accident Model and Process Application:
Quality Control in Medical Device Manufacturing
by
Tieyu Li
M.S. Mechanical Engineering, 2006.University at Buffalo, the State University of New York
M.S. Process Control and Equipment, 2002. East China University of Science and Technology
Diploma Mechanical Engineering, 1989. Shanghai Institute of Technology
Submitted to the System Design and Management Program in Partial Fulfillment of the Requirements for
the Degree of
Master of Science in Engineering and Management
MASSACHUSET INSITrUTE
AT THE OF TECHNOLOGY
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
JUN 2 6 201
September 2012
LIBRARIES
©2012'I eyu Li. All rights reserved.
The authors hereby grant to MIT permission to reproduce and to distribute publicly paper and electronic
copies of this thesis document in whole or in part.
Signature redacted
Signature of Author
Tieyu Li
System Design and Management Program -September 2012
Signature redacted
Certified by
Dr. Qi Van Eikema Hommes
Research Scientist
Xngicering Systejw&Divi*o
Signature redacted
Accepted by
ck Hale
Director System Design and Management Program
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System- Theoretic Process Analysis Application
Quality Control Development in Medical Device Manufacturing
By
Tieyu Li
Submitted to the System Design and Management Program on August 17, 2012 in Partial
Fulfillment of the Requirements for the Degree of Master of Science in Engineering and
Management
ABSTRACT
The goal of medical device industry is to provide patients and healthcare professionals effective,
reliable, safe and affordable products. However, due to the dynamic and competitive operation
and business environment, most manufacturers did not always attain this goal. It is a challenge to
balance the demands of meeting government regulations and containing production costs, in an
effort to produce the most effective, reliable and safest medical devices. The increasing
complexity on product structures, production process and usage context make this task even
more formidable. The increase in serious adverse events has outpaced industry growth by 8 %
since 2001[1], which reflects the insufficiency of traditional quality control measures. The
disastrous consequences of quality hazards usually have profound impact on customers,
manufacturers, and communities. Therefore, it is imperative to look for a better way to achieve
effective quality control in medical device industry.
The purpose of the thesis is to compare the traditional quality control measures, which are now
widely adopted in quality systems of medical device industry for designing and development,
process control and non-conformance handling, with the approach of Systems Theoretic
Accident Model and Process (STAMP) based System-Theoretic Process Analysis (STPA)
method. Through the case study on real quality issue in manufacturing control, this work
analyzes the current states of complex manufacturing process controls that are designed by
utilizing traditional principles and tools, and demonstrates the improvement after the STPA
techniques was applied to the same cases. The advantages of STPA technique is to model the
process to system control structure without oversimplifying any possible influencing factors, and
then examine the links an interaction among these factors to reveal what constraints need to be
installed and are followed to ensure that the system performs in safe zone and deliver the
expected outcomes. This approach can effectively reveal hidden defects and dangers in system
that the traditional measures are not able to detect, and thus is very helpful to the high-stake
industry such as medical device manufacturing to prevent potential serious adverse events and
protect patients from injuries caused by accidents of quality hazards.
Thesis Supervisor: Dr. Qi Van Eikema Hommes
Title: Research Scientist, Engineering System Division
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Acknowledgements
I am heartily thankful to:
Dr. Qi Van Eikema Hommes, my thesis advisor, for her encouragement and insight to guide
me understand the subject and complete this work.
Pat Hale, SDM director of SDM program for his great patient and support to my work.
To my grandma, Xiushi Du.
To my best friend and wife, Xiaoshan Kou for her support of all the time.
Tieyu
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One always fails to see the forest for the trees.
- Chinese Proverb
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Contents
1. Introd uctio n and M otivatio n ................................................................................................................ 9
2 . Lite ratu re Rev iew ................................................................................................................................ 1 1
2.1 Q uality Co ncept and Evolution ...................................................................................................... 11
2.2 A Brief History of Medical Device Regulation and Quality System in the United and States........12
2.3 M edical Device Classification and Regulation ............................................................................ 14
2.4 Medical Device Regulation Environment in the United States................................................... 15
2.4.1 The Food and Drug Administration (USFDA).......................................................................... 16
2.4.2 Center for Device and Radiological Health (CDRH) and Device Approval Process ................. 18
2.4.3 Regulation and Standards .......................................................................................................... 19
2.5 Traditional Risk Management and Quality Control Methods in Medical Device Industry...... 24
2.5.1 Tactical Approach vs. Systemic Approach on Risk Management .............................................. 26
2.5.2 Process Oriented vs. System Oriented on Quality Control and Improvement ...................... 27
2.5.3 Probabilistic Risk Assessm ent (PRA)....................................................................................... 28
2.5.4 Risk Assessment Techniques Recommended by ISO 14971 .................................................. 30
2.5.5 Additional Risk Assessment Techniques Recommended by ISO/IEC 31010:2009................. 35
2.6 Risk Assessment Method Summary and Selection .................................................................... 38
2.7 Quality Challenges in M edical Device Industry........................................................................... 39
2.8 The System-Theoretic Accident Model and Process (STAMP) Approach ................................... 41
3. The Screen Printing Circuit Sheet Case Study ................................................................................. 46
3 .1 P ro d uct Intro d uctio n ..................................................................................................................... 4 7
3.2 M anufacturing Process Introduction......................................................................................... 49
3 .2.1 M aterial Pre paration ............................................................................................................. 49
3.2.2 Ink Pressing and Curing Process......................................................................................... 53
3.2.3 D ie C utting P rocess ............................................................................................................... 55
3.3 Production and Process Quality Control Set up by Current Techniques ................................... 55
3.4 The Process Failure Model Effect and Analysis (PFMEA)........................................................... 60
3 .5 Pro cess C o ntro l P lan ...................................................................................................................... 65
3.6 The Results of PFM EA and Discussion ....................................................................................... 68
4 . T he ST PA A p p ro ach............................................................................................................................. 70
4 .1 The Project Team Fo rm ing ............................................................................................................. 7 1
4.2 High Level Control Structure Developm ent............................................................................... 71
4.3 Define the Hazards of Final Production Quality Performance .................................................. 74
4.4 Operating Process Control Structure and Unsafe Control Actions............................................ 75
4 .4 .1 Ink Pre paratio n Pro cess ........................................................................................................ 75
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4.4.2 Ink Pressing and Curing Process....................................................................................... 85
4.4.3 New Findings in Rest Processes and Im provem ent Actions ............................................ 99
5. Conclusions ....................................................................................................................................... 101
6. References ........................................................................................................................................ 102
Index of Figures
Figure 1 M edical Device Regulation Structure........................................................................................ 16
Figure 2 M edical Device Regulation Application Structure .................................................................... 20
Figure 3 Global Harm onization Task Force Organization Chart.............................................................. 23
Figure 4 Definition of Risk ........................................................................................................................... 25
Figure 5 Cause and Effect m odel ............................................................................................................... 26
Figure 6 A Tactical View of Risk..................................................................................................................26
Figure 7 A System ic View of Risk................................................................................................................. 27
Figure 8 Risk M anagem ent Process ............................................................................................................ 30
Figure 9 Fault Tree Analysis Process ........................................................................................................... 31
Figure 10 A Sam ple of Calculations of anEvent Tree ............................................................................... 36
Figure 11 A Sam ple of Fish Bone Diagram .............................................................................................. 37
Figure 12 The Root Causes of M edical Device Recall 2003-2009 .......................................................... 40
Figure 13 STAM P Control Loop ................................................................................................................... 43
Figure 14 CAST Investigation Flow .............................................................................................................. 45
Figure 15 Patient Brain W ave M onitoring System ................................................................................... 47
Figure 16 Sensor Assem bly Structure ......................................................................................................... 48
Figure 17 The Sensor Circuit Printing M anufacturing Process Flow Chart ............................................ 50
Figure 18 The Illustration of M esh Stretch and Stencil Developm ent ................................................... 53
Figure 19 Ink Pressing Process .................................................................................................................... 54
Figure 20 Flat Bed Ink Pressing M achine ................................................................................................ 54
Figure 21 The Illustration of the Dynam ic System of Screen Printing Process ...................................... 55
Figure 22 The Relation of PFM , PFM EA, PCP, W I and Production Release............................................. 57
Figure 23 The Process Flow M ap of Stencil Developm ent Process ......................................................... 58
Figure 24 The Process Flow M ap of Ink Pressing and Curing Process ..................................................... 59
Figure 25 PFM EA Causality Relationships ................................................................................................ 61
Figure 26 Control Structure Diagram - Level 0....................................................................................... 72
Figure 27 Control Structure Diagram - Level 1....................................................................................... 73
Figure 28 Control Structure Diagram - Level 2....................................................................................... 74
Figure 29 Ink Preparation Process Control Structure .............................................................................. 77
Figure 30 The Casual Factors to Be Considered to Create Scenarios ..................................................... 82
Figure 31 Ink Pressing and Curing Process Control Structure.................................................................. 86
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Index of Tables
Table 1 Milestones of Drug and Medical Device Regulation in United States........................................13
Table 2 The Regulation Responsibilities of FDA Function Groups ........................................................... 17
Table 3 GHTF Harmonized Guidance in Different Countries .............................................................. 24
Table 4 Attributes of Risk Assessm ent Tools ........................................................................................... 39
Table 5 Sensor Screen Printing W ork Cells and Processes ..................................................................... 56
Table 6 The Hihg Risk Items Sum m arized by PFM EA ............................................................................... 62
Table 7 The Control Plan for Each W ork Cell ........................................................................................... 66
Table 8 Sensor Product H azard List ............................................................................................................ 75
Table 9 Identified Hazardous System Behavior of Ink Preparation Process............................................78
Table 10 Ink Preparation Process Hazard Casual Factor List ................................................................... 79
Table 11 Risk Mitigaiton and Control Measures for Ink Preparation Process ........................................ 83
Table 12 Identied Hazardous System Behavior of Ink Pressing and Curing Process .............................. 87
Table 13 Ink Pressing and Curing Process Hazard Casual Factor List ...................................................... 89
Table 14 Risk Mitigatiion and Control Measures for Ink Pressing and Curing Process...........................96
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1. Introduction and Motivation
The medical device industry, one of the fastest growing and most dynamic industries, has
enjoyed tremendous growth in both revenues and the technical complexity of the products that it
produces over the past decades. The annual revenues of medical devices in global market has
been growing from approximately 73.6 billion in 2001,with an average 9% compound annual
growth rate, to$312 billion in 2011 and it is expected to continue the growth in a
6~9%compound annual growth rate through next decade [1] [2].
Medical devices include a wide range of products varying in complexity and application that use
physical, mechanical, thermal, physico-chemical, or chemical means to interact with human
bodies. Medical device products range from simple tongue depressors and bandages to complex
programmable pacemakers and sophisticated imaging systems such as nuclear magnetic
resonance imaging (NMRI) machine. In recent years, the medical device industry has evolved
with both new-entry and established players competing to bring new, life-enhancing innovations
to market. The Medical Devices & Services industry shows a significant rise in innovation recent
years - between 2001 and 2009, nearly 30,000 devices received 510(k) premarket notification
clearance and more than 303 new devices received original premarket approval (PMA). In 2010
alone, 26% more patents were granted than 2009 [3]. These innovations, driven by the evolution
of information technology, breakthroughs on material science and the combination of
pharmaceutical invention, also increased the complexity on medical device structures and their
manufacturing environment. Furthermore, the operation in medical device industry has become
more globalized, allowing the manufacturers to become more cost competitive. In the meantime,
as the result of globalization, the medical device manufacturers have to deal with multiple layers
of thousands of raw material, component, and sub-component suppliers from different countries
and regions, which all have potential impacts on final product quality and performance.
The Medical Device industry is a highly regulated sector of the economy because of the direct
impact and potential risks to healthcare professionals' and patients' health and life. Thus,
regulatory environments, both at home and abroad, have significant implications on the
industry's behavior. From the business environment perspective, mergers and acquisitions in
Medical Device industry are the primary mode to build up product line portfolio, expand market
occupation or exit for early stage companies. During the 10-year period ended on December 31,
2009, there were 1,496 medical device mergers and acquisitions that involved more than $301
billion in funding [4][5]. It is also noteworthy that the public healthcare policies have significant
influences on Medical Device industry in different aspects ranging from business strategy to
operation planning. Thus, it is a challenge for a Medical Device firm in this fast-pace and
complex environment to manage its operation system in order to provide quality and safe
products to its customers consistently.
While the medical device industry and regulatory authority devote considerable resources toward
product approval processes, clinical trials, and plant audits/inspections, there are still numerous
recalls and patient injuries occurring due to medical device hazards. The US Food and Drug
Administration (FDA) requests Medical Device manufacturers, importers and user facilities
report any existing and/or potential serious adverse event to regulatory authority when any
undesirable experience such as death, life-threatening, permanent damage, hospitalization, etc. is
associated with the use of a medical product in a patient [6]. Between 2001 and 2009, the
number of adverse events reported to the Manufacturer and User Facilities Device Experimental
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(MAUDE) database increased in average 15% per year, from approximately 57,000 reported
events in 2001 to more than 207,000 reported events in 2009. Among these adverse events, the
serious adverse event whose outcomes are classified as death, life-threatening, disability, or
hospitalization even has a higher growing rate - 17% per year in average during that time, from
8,000 in 2001 to 28,000 in 2009 [7]. Particularly, the reporting increased around 42% in only
one-year period from 2008 to 2009. Apparently, the number of adverse event reports has
increased dramatically and outpaced overall industry growth by a wide margin.
The consequences of such accidents usually are significant and losses are huge or even not
measureable to both manufacturers and patients. These facts and trends reveal that there are
systemic gaps within the medical device industry's quality approach that result in these issues.
Attempts to improve quality are hindered by the limitation of traditional approaches that are
mainly based on silo thinking. The assurance of continued medical device quality in a complex
and fast-pace context requires something new. The System-Theoretic Process Analysis (STPA)
method based on Systems Theoretic Accident Model and Process is an efficient and powerful
way to improve medical device quality by identifying and addressing systemic causes of quality
problems using a holistic system approach. While medical device flaws may vary by device,
some sources of error are pervasive throughout the field. This thesis through a case study on
process quality control development for a medical sensor manufacturing process demonstrates
the effectiveness and advantages of STPA on analysis of potential systemic risks over traditional
analysis techniques such as Process Failure Mode and Effect Analysis (PFMEA).
This thesis through case studies on typical quality control issues emerging from complex
manufacturing processes tries to answer the question if the STPA method is more effective than
PFMEA method in identifying potential quality failure risks at system level so that the quality
control system could be more comprehensive and robust.
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