integration of artifact detection in clinical decision support systems

162 Pages·2016·4.22 MB·English

INTEGRATION OF ARTIFACT DETECTION IN CLINICAL
DECISION SUPPORT SYSTEMS

by
SHERMEEN NIZAMI

A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in
partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY
in
ELECTRICAL AND COMPUTER ENGINEERING

Ottawa-Carleton Institute of Electrical and Computer Engineering
Department of Systems and Computer Engineering
Carleton University
Ottawa, Ontario, Canada

© 2015
Shermeen Nizami
ABSTRACT
Artifact detection (AD) is a critical component of Clinical Decision Support Systems
(CDSS) to assess the quality of data and issue clinical alarms with high specificity and
low false alarm rates. An in-depth review of the literature reveals that, although many
advanced AD algorithms have been developed, very few have been evaluated in a real-
time environment or reached actual clinical implementation. Furthermore, no single
AD algorithm is necessarily best-suited to serve the varying needs of a CDSS. This
identifies the need to develop and evaluate a framework that supports the
interoperability of a range of configurable AD algorithms that could be integrated with
CDSS.
This thesis develops an AD framework to address six different shortcomings
identified by the literature review. This framework supports the following six features:
(f.1) Flexibility to serve the needs of patient populations from different types of Critical
Care Units (CCU) through generalization and customizability; (f.2) Reusability across
multiple types of physiologic data harvested by different Original Equipment
Manufacturer (OEM) monitors; (f.3) Standardized definitions of Signal Quality
Indicators (SQI) that promote interoperability and comparison between independently
developed components; (f.4) Reusability and scalability by mixing and matching
several AD, Parameter Derivation (PD), and Clinical Event Detection (CED)
components in various combinations; (f.5) Customizability to evaluate and compare
the performance of multiple combinations of independently developed components on
offline and potentially real-time patient data when integrated with clinical workflows;
and (f.6) Standardized component interfaces that can potentially support real-time
clinical implementation of AD.
The developed framework provides for a unique test bed with the ability to
create new AD composition pipelines by mixing and matching independently developed
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or de-coupled AD components. The performance of these pipelines can be evaluated
in integration with CDSS. The AD composition pipeline most suited to a particular
clinical need can then be hard-coded and integrated into the clinical workflow for real-
time implementation. A novel contribution of this research is a Common Reference
Model (CRM) that defines standard interfaces to allow for interoperability of framework
components. The CRM defines patient data attributes including data types and their
SQI.
The framework is validated in a clinical research study. Four experiments are
conducted to evaluate different AD composition pipelines. Each pipeline is evaluated
in integration with an SpO alarms generation CDSS. It is shown that by using the
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framework the lowest achievable false alarm rate is 39% at a sensitivity of 80%, when
compared across all four experiments. The experiments serve to demonstrate and
validate the six features supported by the AD Framework developed here. This
evaluation remains independent of the performance of the particular CED used in the
experiments.

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ACKNOWLEDGEMENTS
I begin with praise to God Almighty, Allah, who has made this journey possible for me.
I would like to express profound gratitude towards my thesis supervisors, Professor
James R. Green and Professor Carolyn McGregor. They have both provided
comprehensive guidance and tremendous support during my doctoral journey at
Carleton. I am grateful to my thesis advisory committee Dr. Adrian Chan, Dr. Ian
Marsland and Dr. Liam Peyton. Their valuable advice and mentoring helped shape my
research and guide me through this important stage in my academic career. I am
indebted to my research collaborators at the Children’s Hospital of Eastern Ontario,
Kim Greenwood, Dr. JoAnn Harrold, and Dr. Nick Barrowman. They dedicated many
hours to discuss the engineering, clinical and statistical aspects of this research. I
would like to acknowledge the generous and selfless support of my friends and
colleagues, Mohamed Abdelazez, Amna Basharat, Georgina Blasetti, Mina S.
Dehghanian, Sonia Hammouda, Maryam Kaka, Jessica Keats, Aly Khedr, Sylvia
Reitmanova, and Romaissa Saadi. Each one of them has contributed to my success in
unique and very special ways. Finally, I will remain forever indebted to my dearest
family for their constant support and encouragement. My parents, Imrana Tariq and
Khaled Nizami, empowered me with the love of learning. I dedicate this thesis to my
sons, Hasan and Yahya, so that it inspires them to be lifelong learners.
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TABLE OF CONTENTS
ABSTRACT ......................................................................................................... ii
ACKNOWLEDGEMENTS.......................................................................................... iv
TABLE OF CONTENTS ............................................................................................ v
LIST OF TABLES ................................................................................................. ix
LIST OF FIGURES ................................................................................................ x
LIST OF ACRONYMS .......................................................................................... xiii
STATEMENT OF ORIGINALITY ............................................................................... xiv
1 INTRODUCTION ............................................................................................. 1
1.1 RESEARCH SIGNIFICANCE ........................................................................ 1
1.2 RESEARCH MOTIVATION .......................................................................... 3
1.3 RESEARCH PROBLEM ............................................................................... 4
1.4 RESEARCH METHOD ................................................................................ 6
1.5 RESEARCH CONTRIBUTIONS ...................................................................... 7
1.6 RESEARCH VALIDATION ........................................................................... 8
1.7 DELIMITATIONS AND LIMITATIONS .............................................................. 9
1.8 THESIS ORGANIZATION ......................................................................... 11
2 LITERATURE REVIEW .................................................................................... 12
2.1 BACKGROUND ..................................................................................... 12
2.1.1 ARTIFACT DETECTION ...................................................................... 12
2.1.2 CLINICAL EVENT DETECTION .............................................................. 14
2.1.3 CLINICAL DECISION SUPPORT SYSTEMS (CDSS) .................................... 16
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2.2 METHODOLOGICAL REVIEW ..................................................................... 19
2.2.1 THEME I. CRITICAL CARE UNIT........................................................... 19
2.2.2 THEME II. PHYSIOLOGIC DATA SOURCE ................................................ 20
2.2.3 THEME III. HARVESTED DATA ............................................................ 23
2.2.4 THEME IV. DATA ANALYSIS ............................................................... 24
2.2.5 THEME V. CLINICAL EVALUATION ........................................................ 27
2.2.6 THEME VI. CLINICAL IMPLEMENTATION ................................................. 29
2.3 RESULTS ........................................................................................... 33
2.4 CONCLUSIONS .................................................................................... 34
2.5 SUMMARY .......................................................................................... 36
3 ARTIFACT DETECTION FRAMEWORK .................................................................. 37
3.1 COMPONENT-BASED SYSTEM DESIGN ......................................................... 37
3.1.1 FRAMEWORK .................................................................................. 37
3.1.2 COMPONENT .................................................................................. 38
3.1.3 INTERFACE .................................................................................... 38
3.2 AD FRAMEWORK DEVELOPMENT ............................................................... 39
3.2.1 FRAMEWORK .................................................................................. 39
3.2.2 COMPONENTS ................................................................................ 40
3.2.3 INTERFACES .................................................................................. 41
3.3 COMPONENT CATALOGUE ....................................................................... 47
3.3.1 ADDIL DE-INTERLACE COMPONENT ...................................................... 47
3.3.2 ADTHRESH THRESHOLD COMPONENT ....................................................... 48
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3.3.3 ADCONVERTSQI CONVERT SQI COMPONENT ............................................... 50
3.3.4 ADFUSESQI FUSE SQI COMPONENT ....................................................... 51
3.3.5 ADDIFF DIFFERENTIAL COMPONENT....................................................... 52
3.3.6 ADMEDFILT MEDIAN FILTER COMPONENT ................................................. 53
3.4 RESEARCH CONTRIBUTIONS .................................................................... 54
3.5 ADVANTAGES AND CHALLENGES ............................................................... 56
3.6 CHAPTER SUMMARY .............................................................................. 57
4 RESEARCH VALIDATION ................................................................................. 59
4.1 DATA ACQUISITION METHODS ................................................................. 61
4.1.1 DATASET ...................................................................................... 61
4.1.2 DATA ANNOTATION ......................................................................... 62
4.1.3 ALARM CATEGORIZATION .................................................................. 63
4.2 AD FRAMEWORK VALIDATION ................................................................. 64
4.2.1 PERFORMANCE EVALUATION ............................................................... 65
4.2.2 PDA COMPONENT FOR FRAMEWORK VALIDATION ..................................... 65
4.2.3 CED COMPONENT FOR SPO2 ALARM GENERATION ................................... 66
4.2.4 EXPERIMENT 1 ............................................................................... 69
4.2.5 EXPERIMENT 2 ............................................................................... 70
4.2.6 EXPERIMENT 3 ............................................................................... 70
4.2.7 EXPERIMENT 4 ............................................................................... 71
4.3 RESULTS ........................................................................................... 75
4.3.1 DATA CHARACTERISTICS ................................................................... 75
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4.3.2 EXPERIMENT 1 RESULTS ................................................................... 77
4.3.3 EXPERIMENT 2 RESULTS ................................................................... 81
4.3.4 EXPERIMENT 3 RESULTS ................................................................... 85
4.3.5 EXPERIMENT 4 RESULTS ................................................................... 90
4.4 DISCUSSION ...................................................................................... 98
4.5 CONCLUSIONS .................................................................................. 101
5 CONCLUSIONS .......................................................................................... 103
5.1 RESEARCH SIGNIFICANCE .................................................................... 103
5.2 RESEARCH CONTRIBUTIONS .................................................................. 103
5.3 FUTURE WORK .................................................................................. 105
APPENDIX A: REVIEW OF THEMES II – VI ............................................................. 107
APPENDIX B: AD COMPONENT INTERFACES ............................................................ 118
APPENDIX C: MASIMO VS. NELLCOR SPO2 COMPARISON ........................................... 120
REFERENCES .................................................................................................. 126

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LIST OF TABLES
TABLE I: THEME I. CRITICAL CARE UNIT (CCU). .................................................................................................. 22
TABLE II: NICU PATIENT DEMOGRAPHICS. ........................................................................................................ 76
TABLE III: NICU OEM MONITOR SETTING. ....................................................................................................... 76
TABLE IV: EXPERIMENT 1 RESULTS ................................................................................................................... 79
TABLE V: EXPERIMENT 2 RESULTS FOR MEDWW OF 5 AND 10 ............................................................................... 81
TABLE VI: EXPERIMENT 2 RESULTS FOR MEDWW OF 12, 15 AND 20 ...................................................................... 82
TABLE VII: EXPERIMENT 3 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 6 ............................ 85
TABLE VIII: EXPERIMENT 3 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 12 ......................... 86
TABLE IX: EXPERIMENT 3 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 18 ........................... 86
TABLE X: EXPERIMENT 4 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 6 ................................ 90
TABLE XI: EXPERIMENT 4 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 12 ............................. 91
TABLE XII: EXPERIMENT 4 RESULTS WHERE ADDIFF COMPONENT IS CONFIGURED WITH SQTHRESH = 18 ............................. 92
TABLE XIII: THE BEST POSSIBLE (SN (% CHANGE IN SN), FAR (% CHANGE IN FAR)) ACHIEVED IN ALL FOUR EXPERIMENTS,
WHERE SN ≥ 80% .............................................................................................................................. 100
TABLE XIV: THE BEST POSSIBLE (SN (% CHANGE IN SN), FAR (% CHANGE IN FAR)) ACHIEVED IN ALL FOUR EXPERIMENTS,
WHERE SN ≥ 75% .............................................................................................................................. 100
TABLE XV: AD COMPONENT INTERFACES USED IN EXPERIMENT 1 .......................................................................... 118
TABLE XVI: AD COMPONENT INTERFACES USED IN EXPERIMENT 2 ......................................................................... 118
TABLE XVII: AD COMPONENT INTERFACES USED IN EXPERIMENT 3 ........................................................................ 118
TABLE XVIII: AD COMPONENT INTERFACES USED IN EXPERIMENT 4 ....................................................................... 119

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LIST OF FIGURES
FIGURE 1-1: PROGRESSIVE TIMELINE SHOWING ARTEMIS RESEARCH COLLABORATIONS. ................................................... 4
FIGURE 2-1: PATIENT DATA ACQUISITION BY AN OEM PHYSIOLOGIC MONITOR WITH BUILT-IN PREPROCESSING INCLUSIVE OF AD,
FOLLOWED BY POST-PROCESSING AD, EITHER STANDALONE OR COUPLED WITH CED AND/OR PD, WITH OUTPUT
VARIABLES RESULTING FROM THE ENTIRE DATA ANALYSIS. ............................................................................... 13
FIGURE 2-2: HIGH-LEVEL VIEW OF THE ARTEMIS FRAMEWORK. ............................................................................... 18
FIGURE 2-3: OVERVIEW OF THE SIX THEMATIC TAXONOMIES ................................................................................. 21
FIGURE 3-1: STATIC MODEL OF THE MULTIVARIATE COMPONENT-BASED AD FRAMEWORK. ............................................ 40
FIGURE 3-2: CRM SCHEMA FOR REQUIREMENT AND PROVISION INTERFACES. ............................................................. 45
FIGURE 3-3: SQI FIELDS DEVELOPED AS PART OF THE CRM .................................................................................... 46
FIGURE 3-4: COLOR-CODED LEGEND OF THE CRM TUPLE ...................................................................................... 46
FIGURE 3-5: LOW-LEVEL CODE FOR THE ADDIL COMPONENT ................................................................................... 48
FIGURE 3-6: LOW-LEVEL CODE FOR THE ADTHRESH COMPONENT ............................................................................... 49
FIGURE 3-7: LOW-LEVEL CODE FOR THE ADCONVERTSQI COMPONENT .......................................................................... 50
FIGURE 3-8: ILLUSTRATION OF ADFUSESQI INTEGRATED WITH ADCONVERTSQI ................................................................... 51
FIGURE 3-9: LOW-LEVEL CODE FOR THE ADFUSESQI COMPONENT .............................................................................. 51
FIGURE 3-10: LOW-LEVEL CODE FOR THE ADDIFF COMPONENT ................................................................................ 52
FIGURE 4-1: LOW-LEVEL COMPONENT CODE FOR CLINICAL EVENT DETECTION AND GENERATION OF SPO2 ALARMS ............... 68
FIGURE 4-2: EXPERIMENT 1 FLOWCHART .......................................................................................................... 71
FIGURE 4-3: EXPERIMENT 2 FLOWCHART .......................................................................................................... 72
FIGURE 4-4: EXPERIMENT 3 FLOWCHART .......................................................................................................... 73
FIGURE 4-5: EXPERIMENT 4 FLOWCHART .......................................................................................................... 74
FIGURE 4-6: EXPERIMENT 1 RESULTS OF SN AND FAR PLOTTED AS PERCENTAGES FOR TUNABLE PARAMETER CEDDT ............ 79
FIGURE 4-7: RADAR PLOT FOR EXPERIMENT 1 SHOWS SN VS. FAR FOR VARIOUS CED DECISION THRESHOLDS (CEDDT). EACH
PAIR AROUND THE PERIMETER REPRESENTS (FAR, CEDDT). FAR VALUES DECREASE IN A COUNTER-CLOCKWISE DIRECTION.
....................................................................................................................................................... 80
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