HFE Covered Material 2011

 

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Part 2: Human Factors Engineering Course Contents

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(Covered material that will be included in the exam are marked in Red color - other parts are not included)

 

General Considerations and Principles of Human Factors Engineering in Medical Device Design

 

4 General principles .............................................................................................................................................14

4.1 Introduction ................................................................................................................................................14

4.2 Seek user input..........................................................................................................................................14

4.2.1 Involve users early and often........................................................................................................14

4.2.2 Refine designs through usability testing .......................................................................................14

4.3 Establish design priorities ...........................................................................................................................14

4.3.1 Keep it simple ...............................................................................................................................14

4.3.2 Ensure safe use............................................................................................................................15

4.3.3 Ensure essential communication ..................................................................................................15

4.3.4 Anticipate device failures..............................................................................................................16

4.3.5 Facilitate workflow ........................................................................................................................16

4.4 Accommodate user characteristics and capabilities ...................................................................................16

4.4.1 Do not expect users to become masters ......................................................................................16

4.4.2 Expect user errors ........................................................................................................................17

4.4.3 Accommodate diverse users ........................................................................................................17

4.4.4 Maximize accessibility ..................................................................................................................18

4.4.5 Consider external factors that influence task performance...........................................................18

4.5 Accommodate users' needs and preferences.............................................................................................19

4.5.1 Prioritize user input.......................................................................................................................19

4.5.2 Do not rely exclusively on "thought leaders".................................................................................19

4.5.3 Let users set the pace ..................................................................................................................19

4.6 Establish realistic expectations of users .....................................................................................................19

4.6.1 Do not rely on training ..................................................................................................................19

4.6.2 Do not rely on instructions for use ................................................................................................19

4.6.3 Do not rely on warnings................................................................................................................20

4.6.4 Do not rely on users' memory.......................................................................................................20

4.6.5 Avoid information overload ...........................................................................................................20

4.6.6 Do not assign users tasks that are better suited to the device .....................................................20

4.7 Consider real-world demands .....................................................................................................................21

4.7.1 Consider the context of use..........................................................................................................21

4.7.2 Consider worst-case scenarios.....................................................................................................21

4.7.3 Make devices as rugged as necessary.........................................................................................22

4.7.4 Limit user workload.......................................................................................................................22

4.7.5 Consider the potential for device migration into other uses or use environments.........................22

4.8 Develop compatible designs .......................................................................................................................23

4.8.1 Accommodate mental models ......................................................................................................23

4.8.2 Establish natural or conventional mappings .................................................................................23

4.8.3 Follow industry conventions and consensus standards................................................................24

4.9 Optimize user interactions to enhance safety and effectiveness ................................................................24

4.9.1 Make devices error-tolerant and fail in a safe manner..................................................................24

4.9.2 Avoid physical strain, repetitive motions, and cumulative traumas...............................................24

4.9.3 Help users anticipate future events ..............................................................................................24

4.9.4 Confirm important actions.............................................................................................................24

4.9.5 Make critical controls robust and guard them...............................................................................25

4.9.6 Clarify operational modes.............................................................................................................25

4.9.7 Employ redundant coding.............................................................................................................25

4.9.8 Design to prevent user confusion .................................................................................................26

4.9.9 Don't neglect device appeal..........................................................................................................26

4.10 Summary...................................................................................................................................................26

4.11 References................................................................................................................................................27

 

5 Managing the risk of use error ...........................................................................................................................29

5.1 Introduction ................................................................................................................................................29

5.1.1 Overview .....................................................................................................................................29

5.1.2 Use-related hazards vs. traditional device-failure hazards ...........................................................29

5.1.3 Behavioral variability in human users ...........................................................................................30

5.1.4 Definition of use error ...................................................................................................................30

5.2 Types of use errors....................................................................................................................................30

5.3 General considerations for managing use-related hazards.........................................................................34

5.3.1 Use-error consequences in regulatory submissions .....................................................................34

5.3.2 General considerations for managing risk ....................................................................................34

5.4 Methods of managing the risk of use errors................................................................................................34

5.4.1 Overview .....................................................................................................................................34

5.4.2 Risk, risk management, and use safety........................................................................................34

5.4.3 Use-error risk management process ............................................................................................35

5.5 Definition of intended use, user, and the use environment .........................................................................36

5.6 Identification of use-related hazards ...........................................................................................................37

5.6.1 Overview .....................................................................................................................................37

5.6.2 Analysis of predecessor and similar devices ................................................................................37

5.6.3 Analysis of device use tasks.........................................................................................................37

5.6.4 Application of best practice for user-interface design ...................................................................38

5.6.5 Consideration of user workload in device use ..............................................................................38

5.7 Estimation and prioritization of risk of use-related hazards.........................................................................38

5.7.1 Overview .....................................................................................................................................38

5.7.2 Failure mode effects analysis .......................................................................................................38

5.7.3 Fault tree analysis ........................................................................................................................39

5.7.4 Usability testing ............................................................................................................................39

5.8 Implementation of risk controls ...................................................................................................................40

5.8.1 Overview .....................................................................................................................................40

5.8.2 Most preferred use-related hazard mitigation strategies...............................................................40

5.8.3 Less preferred use-related hazard mitigation strategies...............................................................40

5.9 Validation of safety of use (effectiveness of risk controls)...........................................................................41

5.10 Decision on whether risks are acceptable..................................................................................................41

5.11 Determination of whether new risks were introduced.................................................................................41

5.12 Documentation of the use-related risk management process ....................................................................41

5.13 Monitoring, identification, and control of use-related issues post-marketing ..............................................42

5.14 Summary...................................................................................................................................................42

5.15 References................................................................................................................................................42

 

6 Basic human skills and abilities.........................................................................................................................44

6.1 Introduction ................................................................................................................................................44

6.2 Design guidelines ......................................................................................................................................44

6.2.1 Overview .....................................................................................................................................44

6.2.2 Vision...........................................................................................................................................44

6.2.3 Audition and speech.....................................................................................................................55

6.2.4 Other sensory modalities..............................................................................................................58

6.2.5 Human information processing.....................................................................................................60

6.2.6 Human memory...........................................................................................................................62

6.2.7 Human response capabilities........................................................................................................65

6.2.8 Human vs. machine capabilities ...................................................................................................67

6.3 References ................................................................................................................................................68

 

7 Anthropometry and biomechanics.....................................................................................................................71

7.1 Introduction ................................................................................................................................................71

7.2 General considerations ...............................................................................................................................71

7.3 Anthropometric design guidance ................................................................................................................72

7.3.1 Overview .....................................................................................................................................72

7.3.2 Anthropometric data .....................................................................................................................72

7.3.3 One-dimensional measurements..................................................................................................73

7.3.4 Mobility and functional measurements .........................................................................................82

7.3.5 Strength.......................................................................................................................................87

7.3.6 Derivation of missing data ............................................................................................................95

7.4 Biomechanical design guidance .................................................................................................................96

7.4.1 Overview .....................................................................................................................................96

7.4.2 Critical design considerations .......................................................................................................96

7.4.3 Special considerations.................................................................................................................98

7.4.4 Design guidelines for tasks involving lifting ..................................................................................98

7.5 References ................................................................................................................................................102

 

8 Environmental considerations ............................................................................................................................105

8.1 Introduction ................................................................................................................................................105

8.2 General considerations ...............................................................................................................................105

8.3 Design guidelines ......................................................................................................................................106

8.3.1 Interruptions and distractions........................................................................................................106

8.3.2 Acoustic noise ..............................................................................................................................106

8.3.3 Lighting........................................................................................................................................109

8.3.4 Temperature and humidity............................................................................................................110

8.3.5 Vibration ......................................................................................................................................111

8.3.6 Slipperiness and friction ...............................................................................................................112

8.3.7 Atmospheric pressure...................................................................................................................112

8.3.8 Ease of maintenance....................................................................................................................112

8.3.9 Storage........................................................................................................................................113

8.3.10 Mounting of devices......................................................................................................................113

8.3.11 Radiant energy .............................................................................................................................113

8.3.12 Emergency environment...............................................................................................................113

8.3.13 Home environment .......................................................................................................................114

8.4 References ................................................................................................................................................114

 

9 Usability testing.................................................................................................................................................116

9.1 Introduction ................................................................................................................................................116

9.2 General considerations ...............................................................................................................................116

9.3 Design guidelines ......................................................................................................................................117

9.3.1 Types of usability tests .................................................................................................................117

9.3.2 Principles of good usability test design.........................................................................................117

9.3.3 Overview of usability testing .........................................................................................................118

9.3.4 Content of the usability test plan...................................................................................................121

9.3.5 Logistics ......................................................................................................................................129

9.3.6 Protocol-related activities .............................................................................................................132

9.3.7 Supplemental usability evaluation methods..................................................................................136

9.4 References ................................................................................................................................................137

 

10 Signs, symbols, and markings ...........................................................................................................................139

10.1 Introduction ...........................................................................................................................................139

10.2 General considerations ...........................................................................................................................139

10.3 Design guidelines ..................................................................................................................................140

10.3.1 Overview .....................................................................................................................................140

10.3.2 Labels for equipment identification ...............................................................................................140

10.3.3 Descriptions of equipment functions.............................................................................................140

10.3.4 Hazard labels...............................................................................................................................140

10.3.5 Electrical receptacle and connector labels ...................................................................................141

10.3.6 Fuse and circuit-breaker labels.....................................................................................................141

10.3.7 Labels on controls, keyboards, and keypads................................................................................143

10.3.8 Positioning and mounting of labels ...............................................................................................143

10.3.9 Label orientation..........................................................................................................................143

10.3.10 Indications of functional relationships ...........................................................................................143

10.3.11 Permanence and durability of labels.............................................................................................144

10.4 Specific design guidance ........................................................................................................................144

10.4.1 Consistency.................................................................................................................................144

10.4.2 Label content ...............................................................................................................................144

10.4.3 Use of symbols............................................................................................................................145

10.4.4 Legibility ......................................................................................................................................146

10.4.5 Coding .........................................................................................................................................147

10.4.6 Application of color to mimics and flow lines ................................................................................148

10.4.7 Flow lines ....................................................................................................................................148

10.4.8 Language ....................................................................................................................................148

10.4.9 Package labels .............................................................................................................................148

10.4.10 Hierarchical schemes ...................................................................................................................148

10.5 References.............................................................................................................................................149

 

11 User documentation..........................................................................................................................................151

11.1 Introduction ...........................................................................................................................................151

11.2 General considerations ...........................................................................................................................151

11.2.1 Overview .....................................................................................................................................151

11.2.2 Overall process for user documentation development..................................................................152

11.2.3 Basic design principles for layout, comprehension, and organization...........................................154

11.2.4 Control of user risks......................................................................................................................159

11.2.5 Documentation design for diverse environments..........................................................................160

11.3 Specific design guidelines for various types of user documentation .......................................................160

11.3.1 Overview .....................................................................................................................................160

11.3.2 User guides, operator manuals, and owner’s manuals.................................................................160

11.3.3 Quick-reference guides ................................................................................................................161

11.3.4 Electronic documentation .............................................................................................................162

11.4 References.............................................................................................................................................164

 

12 Packaging design..............................................................................................................................................166

12.1 Introduction ...........................................................................................................................................166

12.2 General considerations ...........................................................................................................................166

12.2.1 Overview .....................................................................................................................................166

12.2.2 The user ......................................................................................................................................166

12.2.3 The use environment....................................................................................................................167

12.3 Principles of good medical packaging design .........................................................................................168

12.3.1 Overview .....................................................................................................................................168

12.3.2 Opening packages.......................................................................................................................168

12.3.3 Assembling or sequentially using components.............................................................................170

12.3.4 Labeling packages.......................................................................................................................171

12.3.5 Identifying devices ........................................................................................................................172

12.3.6 Indicating sterilization status.........................................................................................................172

12.3.7 Storing packaged devices ............................................................................................................173

12.3.8 Handling packaged devices..........................................................................................................174

12.3.9 Disposing of packaging ................................................................................................................174

12.4 References.............................................................................................................................................174

 

13 Design for post-market issues...........................................................................................................................176

13.1 Introduction ...........................................................................................................................................176

13.2 General considerations ...........................................................................................................................178

13.2.1 Type of user: health care professional or home-use consumer....................................................178

13.2.2 Type of use environment: health care facility or home .................................................................178

13.2.3 Device longevity ...........................................................................................................................178

13.3 Design guidelines ..................................................................................................................................179

13.3.1 Overview .....................................................................................................................................179

13.3.2 Disposables .................................................................................................................................179

13.3.3 Single-use devices .......................................................................................................................179

13.3.4 Labeling.......................................................................................................................................180

13.3.5 Setup and installation ...................................................................................................................180

13.3.6 Routine maintenance....................................................................................................................181

13.3.7 Repair..........................................................................................................................................181

13.3.8 Upgrades.....................................................................................................................................183

13.3.9 Obsolescence..............................................................................................................................183

13.3.10 Disposal.......................................................................................................................................183

13.4 References.............................................................................................................................................184

 

14 Cross-cultural/cross-national design ..................................................................................................................185

14.1 Introduction ...........................................................................................................................................185

14.2 General considerations ...........................................................................................................................186

14.2.1 Differences among nations and cultures ......................................................................................186

14.2.2 National issues .............................................................................................................................187

14.2.3 Cultural issues .............................................................................................................................189

14.2.4 Culture-specific or nation-specific user profiles ............................................................................190

14.3 Guidelines for cross-cultural/cross-national design.................................................................................194

14.3.1 Overview .....................................................................................................................................194

14.3.2 Direct issues associated with the user–device interface...............................................................195

14.3.3 Indirect issues associated with the user–device interface ............................................................198

14.3.4 Cross-cultural/cross-national design process ...............................................................................200

14.4 Summary ...............................................................................................................................................201

14.5 References.............................................................................................................................................202

 

15 Alarm design .....................................................................................................................................................205

15.1 Introduction ...........................................................................................................................................205

15.2 General considerations ...........................................................................................................................205

15.2.1 Overview .....................................................................................................................................205

15.2.2 Goals...........................................................................................................................................206

15.2.3 Verifying that the alarm system works ..........................................................................................206

15.2.4 Initializing alarm monitoring ..........................................................................................................207

15.2.5 Avoiding false alarms ...................................................................................................................207

15.3 Considerations regarding specific requirements from IEC 60601-1-8.....................................................207

15.3.1 Attended-use model .....................................................................................................................207

15.3.2 Distributed alarm systems ............................................................................................................209

15.3.3 Alarm priority, urgency of response, and allowable latency..........................................................210

15.3.4 Distributed-alarm-system requirements of IEC 60601-1-8............................................................211

15.3.5 “Latching” alarm signals ...............................................................................................................212

15.3.6 Initiation and termination of alarm signals ....................................................................................212

15.3.7 Default alarm limits and alarm-limit adjustment ............................................................................213

15.3.8 Alarm-system inactivation states ..................................................................................................214

15.3.9 Simultaneous monitoring of multiple physiological states.............................................................215

15.4 Step-by-step guidelines for developing an alarm system........................................................................216

15.4.1 Developing an alarm system ........................................................................................................216

15.4.2 Gathering information ...................................................................................................................216

15.4.3 Generating a list of alarm conditions that require alarm signals ...................................................216

15.4.4 Creating signal-processing algorithms..........................................................................................216

15.4.5 Identifying the information to communicate about alarm conditions .............................................217

15.4.6 Allocating signaling modalities to alarm signals............................................................................217

15.4.7 Creating alarm signals for each signaling modality: visual alarm signals .....................................219

15.4.8 Creating alarm signals for each signaling modality: auditory alarm signals..................................220

15.4.9 Creating alarm signals for each signaling modality: other alarm signals ......................................223

15.4.10 Creating a simulated use environment .........................................................................................223

15.4.11 Testing prototype alarm systems with potential users ..................................................................225

15.4.12 Refining alarm systems on the basis of testing results .................................................................226

15.5 References ............................................................................................................................................226

 

16 Accessibility considerations ...............................................................................................................................229

16.1 Introduction ...........................................................................................................................................229

16.2 General considerations ...........................................................................................................................229

16.2.1 User considerations.....................................................................................................................229

16.2.2 Design considerations ..................................................................................................................230

16.3 Design guidelines based on legislative guidance documents .................................................................232

16.3.1 Overview .....................................................................................................................................232

16.3.2 Users with lower-extremity disabilities ..........................................................................................232

16.3.3 Users with upper-extremity disabilities .........................................................................................234

16.3.4 Users who are deaf or hard of hearing .........................................................................................234

16.3.5 Users who are blind or have visual impairments ..........................................................................235

16.3.6 Users with limited tactile sensitivity...............................................................................................237

16.3.7 Users with cognitive or memory impairments ...............................................................................237

16.3.8 Users who could benefit from having more time for device operation ..........................................237

16.3.9 Users with speech impairments....................................................................................................237

16.4 Research-based design guidelines for patient-support surfaces ............................................................237

16.4.1 Overview .....................................................................................................................................237

16.4.2 Width of device base ....................................................................................................................237

16.4.3 Clearance for lift equipment..........................................................................................................238

16.4.4 Adjustability of surface height .......................................................................................................238

16.4.5 Transfer path ...............................................................................................................................238

16.4.6 Hand-holds ..................................................................................................................................238

16.4.7 Contact surfaces..........................................................................................................................239

16.4.8 Controls for support surfaces........................................................................................................240

16.5 Design guidelines for Web-based, mobile, and home-use health care products based on industry

guidance documents...........................................................................................................................240

16.5.1 Overview .....................................................................................................................................240

16.5.2 Existing guidelines and standards ................................................................................................240

16.5.3 Built-in multimodal capabilities......................................................................................................241

16.5.4 Devices that use home-based technologies .................................................................................241

16.5.5 Existing laws related to use of hearing aids with telecommunication products.............................241

16.5.6 Training and informational materials.............................................................................................241

16.6 References.............................................................................................................................................241

 

Design Elements

17 Connectors and connections.............................................................................................................................244

17.1 Introduction ...........................................................................................................................................244

17.2 General considerations ...........................................................................................................................244

17.2.1 Overview .....................................................................................................................................244

17.2.2 Critical design considerations .......................................................................................................245

17.2.3 Key design criteria issues.............................................................................................................245

17.2.4 Types of connection failures .........................................................................................................245

17.3 Prioritizing types of connections .............................................................................................................246

17.3.1 Overview .....................................................................................................................................246

17.3.2 Direct patient connections for therapeutic purposes.....................................................................248

17.3.3 Direct patient connections for diagnostic purposes ......................................................................248

17.3.4 Connections between patient and device .....................................................................................249

17.3.5 Routinely connected non-patient connections ..............................................................................249

17.3.6 Permanent exterior device connections........................................................................................250

17.3.7 Permanent connections inside devices ........................................................................................250

17.4 Differentiating connectors .......................................................................................................................250

17.4.1 Overview .....................................................................................................................................250

17.4.2 Active differentiators .....................................................................................................................250

17.4.3 Passive differentiators ..................................................................................................................252

17.5 Preventing disconnections ......................................................................................................................253

17.5.1 Overview .....................................................................................................................................253

17.5.2 Rotating locking rings ...................................................................................................................253

17.5.3 Push–pull locking devices ............................................................................................................254

17.5.4 Locking levers..............................................................................................................................254

17.5.5 Screw-captive devices..................................................................................................................254

17.5.6 Capture clips................................................................................................................................254

17.5.7 Friction fit.....................................................................................................................................254

17.5.8 Positive feedback .........................................................................................................................255

17.5.9 Engagement of the locking mechanism........................................................................................255

17.5.10 Engagement indicators.................................................................................................................255

17.6 Facilitating connections..........................................................................................................................255

17.6.1 Connector design (shape, fit, feature) ..........................................................................................255

17.6.2 Receptacle design........................................................................................................................256

17.6.3 Connector use and testing and user training ................................................................................257

17.7 Preventing misconnections .....................................................................................................................257

17.8 Protecting connectors .............................................................................................................................257

17.9 User documentation...............................................................................................................................258

17.10 References...........................................................................................................................................258

 

18 Controls ............................................................................................................................................................259

18.1 Introduction ...........................................................................................................................................259

18.2 General considerations ...........................................................................................................................259

18.2.1 Steps in specifying controls ..........................................................................................................259

18.2.2 Advantages and disadvantages of various types of controls ........................................................260

18.2.3 Control selection..........................................................................................................................260

18.2.4 Human factors principles that apply to all controls........................................................................262

18.2.5 Design considerations for medical device controls vs. controls for consumer products ...............263

18.3 Design guidelines ..................................................................................................................................264

18.3.1 Control-panel controls ..................................................................................................................264

18.3.2 Input devices ...............................................................................................................................273

18.3.3 Large mechanical controls............................................................................................................285

18.4 References.............................................................................................................................................288

 

19 Visual displays ..................................................................................................................................................290

19.1 Introduction ...........................................................................................................................................290

19.2 General considerations ...........................................................................................................................290

19.2.1 Overview .....................................................................................................................................290

19.2.2 Understanding and accommodating user population characteristics............................................290

19.2.3 Accommodating the range of user postures .................................................................................291

19.2.4 Determining typical mounting positions and variations in mounting positions ..............................291

19.2.5 Examining the physical environmental conditions ........................................................................291

19.2.6 Identifying the requirements for displayed information .................................................................291

19.2.7 Performing objective display measurements ................................................................................292

19.2.8 Conducting usability tests.............................................................................................................293

19.3 Guidelines for specifying visual-display performance .............................................................................293

19.3.1 Overview .....................................................................................................................................293

19.3.2 Visual-display viewing conditions .................................................................................................293

19.3.3 Spatial characteristics..................................................................................................................294

19.3.4 Temporal characteristics ..............................................................................................................295

19.3.5 Luminance and color characteristics ............................................................................................297

19.4 Guidelines for display formatting.............................................................................................................299

19.4.1 Size and spacing of displayed characters or symbols ..................................................................299

19.4.2 Font style.....................................................................................................................................300

19.4.3 Character, line, and word spacing ................................................................................................301

19.4.4 Size of color objects and alphanumeric strings.............................................................................301

19.5 Guidelines for displaying data .................................................................................................................301

19.5.1 Precision......................................................................................................................................301

19.5.2 Adequate signal duration..............................................................................................................301

19.6 Guidelines for selecting electronic visual displays ..................................................................................302

19.6.1 Comparison of major types of visual displays...............................................................................302

19.6.2 Liquid crystal displays...................................................................................................................303

19.6.3 Active-matrix vs. passive-matrix displays .....................................................................................303

19.6.4 Large-screen displays ..................................................................................................................303

19.6.5 Scale indicators ............................................................................................................................304

19.7 References.............................................................................................................................................307

 

20 Use of automation.............................................................................................................................................309

20.1 Introduction ...........................................................................................................................................309

20.2 General considerations ...........................................................................................................................309

20.2.1 Types of automated systems and common issues .......................................................................309

20.2.2 Automation vs. human tradeoffs in medical systems....................................................................311

20.2.3 Automation status.........................................................................................................................312

20.2.4 User understanding of the automation..........................................................................................312

20.3 Design guidelines ..................................................................................................................................313

20.3.1 Monitoring and alarm systems......................................................................................................313

20.3.2 Event-sequencing systems...........................................................................................................313

20.3.3 Decision-support systems ............................................................................................................313

20.3.4 Closed-loop physiological control systems ...................................................................................313

20.3.5 Hybrid or composite automation systems.....................................................................................313

20.4 References.............................................................................................................................................314

 

21 Software–user interfaces ..................................................................................................................................315

21.1 Introduction ...........................................................................................................................................315

21.1.1 Overview .....................................................................................................................................315

21.1.2 Sample software–user interfaces .................................................................................................315

21.1.3 Factors influencing software–user interface design......................................................................316

21.2 General considerations ...........................................................................................................................317

21.2.1 Overview .....................................................................................................................................317

21.2.2 Make the software–user interface easy to use .............................................................................318

21.2.3 Focus on user tasks .....................................................................................................................318

21.2.4 Provide user guidance..................................................................................................................318

21.2.5 Safeguard against use error .........................................................................................................318

21.2.6 Optimize interaction requirements................................................................................................319

21.2.7 Improve software and hardware integration .................................................................................319

21.2.8 Select the interaction style............................................................................................................320

21.2.9 Support product evolution............................................................................................................320

21.3 Special considerations ............................................................................................................................321

21.3.1 Overview .....................................................................................................................................321

21.3.2 Screen size..................................................................................................................................321

21.3.3 Compatibility................................................................................................................................321

21.3.4 Information priority.......................................................................................................................321

21.3.5 Information legibility.....................................................................................................................321

21.3.6 User population ............................................................................................................................321

21.3.7 Standardization............................................................................................................................322

21.3.8 System integration.......................................................................................................................322

21.4 Design guidelines ..................................................................................................................................322

21.4.1 Categories ...................................................................................................................................322

21.4.2 Conceptual model.........................................................................................................................323

21.4.3 User-interface structure ................................................................................................................323

21.4.4 Interaction style ............................................................................................................................324

21.4.5 Screen layout...............................................................................................................................325

21.4.6 Legibility ......................................................................................................................................326

21.4.7 Aesthetics ....................................................................................................................................328

21.4.8 Data entry....................................................................................................................................329

21.4.9 Color............................................................................................................................................331

21.4.10 Dynamic displays.........................................................................................................................333

21.4.11 Special interactive mechanisms ...................................................................................................335

21.4.12 User support ................................................................................................................................341

21.4.13 Consistency.................................................................................................................................343

21.5 References.............................................................................................................................................343

 

Integrated Solutions

22 Hand tool design ...............................................................................................................................................344

22.1 Introduction ...........................................................................................................................................344

22.2 General considerations ...........................................................................................................................346

22.2.1 Overview .....................................................................................................................................346

22.2.2 Biomechanics ...............................................................................................................................346

22.2.3 Hand grips and positions associated with tool use .......................................................................346

22.2.4 Forces associated with the use of hand tools...............................................................................347

22.2.5 Injuries and discomfort associated with tool use...........................................................................348

22.2.6 Risk factors..................................................................................................................................349

22.2.7 Compensatory strategies and tradeoffs........................................................................................350

22.3 Special considerations ............................................................................................................................351

22.3.1 Laparoscopic surgery ...................................................................................................................351

22.3.2 Catheter-based procedures..........................................................................................................353

22.3.3 What to do if design data are not available...................................................................................354

22.4 Design guidelines ..................................................................................................................................355

22.4.1 Overview .....................................................................................................................................355

22.4.2 Context of use ..............................................................................................................................355

22.4.3 Location and environmental factors..............................................................................................355

22.4.4 The end-effector (tool interactions with anatomy).........................................................................357

22.4.5 Characteristics of the tool .............................................................................................................358

22.4.6 Safety ..........................................................................................................................................364

22.4.7 User characteristics and related design considerations................................................................364

22.4.8 Controls for hand tools .................................................................................................................370

22.4.9 Sensory feedback........................................................................................................................372

22.4.10 Guidelines specifically for laparoscopic instrument design...........................................................372

22.5 References.............................................................................................................................................373

 

23 Workstations .....................................................................................................................................................378

23.1 Introduction ...........................................................................................................................................378

23.2 General considerations ...........................................................................................................................380

23.2.1 Adaptation of design to user needs ..............................................................................................380

23.2.2 Safety ..........................................................................................................................................381

23.2.3 Usability.......................................................................................................................................381

23.2.4 User satisfaction ...........................................................................................................................383

23.3 Special considerations ............................................................................................................................383

23.3.1 Overview .....................................................................................................................................383

23.3.2 Serve life-critical purposes............................................................................................................383

23.3.3 Accommodate evolving clinical practices .....................................................................................383

23.3.4 Accommodate a variety of user positions .....................................................................................383

23.3.5 Accommodate users with varying degrees of skill, training, and experience ................................384

23.3.6 Accommodate workstation use by individuals with disabilities .....................................................384

23.3.7 Accommodate patients who might be under stress ......................................................................384

23.3.8 Accommodate caregivers who might be under stress ..................................................................384

23.3.9 Anticipate potential migration from hospital to home use .............................................................384

23.3.10 Anticipate frequent or infrequent cleaning ....................................................................................384

23.3.11 Design for compactness ...............................................................................................................385

23.4 Design guidelines ..................................................................................................................................385

23.4.1 Overview .....................................................................................................................................385

23.4.2 Operational factors .......................................................................................................................385

23.4.3 Power supply...............................................................................................................................388

23.4.4 Readiness ...................................................................................................................................389

23.4.5 Security .......................................................................................................................................389

23.4.6 Privacy.........................................................................................................................................390

23.4.7 Communication............................................................................................................................390

23.4.8 Component configuration .............................................................................................................392

23.4.9 Physical interaction......................................................................................................................400

23.4.10 User accommodations.................................................................................................................405

23.4.11 Environmental factors...................................................................................................................415

23.5 References.............................................................................................................................................415

 

24 Design of mobile medical devices......................................................................................................................417

24.1 Introduction ...........................................................................................................................................417

24.2 General considerations ...........................................................................................................................417

24.2.1 Overview .....................................................................................................................................417

24.2.2 User considerations.....................................................................................................................417

24.2.3 Use-environment considerations ..................................................................................................417

24.3 Design guidelines ..................................................................................................................................418

24.3.1 General design guidance..............................................................................................................418

24.3.2 Mechanical design........................................................................................................................418

24.3.3 Electrical design ...........................................................................................................................421

24.3.4 Display of information on computer-based medical devices.........................................................421

24.3.5 Controls and input devices ...........................................................................................................425

24.3.6 Connectors and cables.................................................................................................................426

24.3.7 Security .......................................................................................................................................427

24.3.8 Instruction manuals and other forms of device documentation.....................................................427

24.4 References ............................................................................................................................................427

 

25 Home health care..............................................................................................................................................428

25.1 Introduction ...........................................................................................................................................428

25.1.1 Trends in medical device use .......................................................................................................428

25.1.2 The home user .............................................................................................................................428

25.1.3 The home environment.................................................................................................................428

25.2 General considerations ...........................................................................................................................429

25.2.1 Overview .....................................................................................................................................429

25.2.2 Adjustability .................................................................................................................................429

25.2.3 Durability .....................................................................................................................................429

25.2.4 Learnability and intuitiveness........................................................................................................429

25.2.5 Freedom from calibration, maintenance, and repair .....................................................................429

25.2.6 Protection from unintended misuse and/or tampering ..................................................................429

25.2.7 Portability and maneuverability.....................................................................................................430

25.2.8 Power requirements .....................................................................................................................430

25.2.9 Aesthetics and unobtrusiveness...................................................................................................430

25.2.10 User guidance and training...........................................................................................................430

25.3 Design guidelines ..................................................................................................................................430

25.3.1 Overview .....................................................................................................................................430

25.3.2 Design guidance related to sensory capabilities and limitations ...................................................431

25.3.3 Design guidance related to cognitive capabilities and limitations .................................................434

25.3.4 Design guidance related to physical capabilities and limitations ..................................................436

25.3.5 Design guidance related to the use environment..........................................................................437

25.3.6 Medical device training materials and documentation for home users .........................................438

 

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Last modified: February 14, 2012