Lecture 7: Incorporating Human Factors

Engineering into Clinical Management

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Outline

Clinical Engineers (Historical) Human Factors/ Ergonomics

Device Limitations Use of Human Capabilities Environmental Factors Culture HFE Techniques

Failure Mode and Effect Analysis Heuristic Evaluation

Conclusion

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Clinical Engineers (Historical) Proliferation of new medical technologies Need for engineering experts in medical

instrumentation and devices Patient safety related activities Need for more than the maintenance and repair

of equipment Incident investigator of equipment related

injuries Adherence to regulatory codes and standards

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Clinical Engineers in Health Care Today “ A Clinical Engineer is a professional who

supports and advances patient care by applying engineering and managerial skills to healthcare technology” (Gebara, R.)

Project Management Technology Assessment Technology Management Risk Management Standards Compliance Training/Education

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Driving Forces for Patient’s Safety It’s the right thing to do for our patients The IOM Reports and Recommendations JCAHO Standards National Patient Safety Goals Safe Medical Device Act Financial implications of errors Public awareness and concern

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How can Clinical Engineers Contribute to Patient’s Safety? Use Human Factors Engineering research

to evaluate medical devices and investigate medical incidents

Identify critical safety initiatives and provide a short term solutions

Collect data for future planning and improvements aiming for optimal product design and quality

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Human Factors / Ergonomics

Human factor is defined as “the study of how humans accomplish work-related tasks in the context of human-machine system operation, and how behavioral and non-behavioral variables affect that accomplishment” – Meister (1989)

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Human Factors Engineering / Ergonomics An engineering discipline that looks to

understand the relationship between people and the systems that surround them to understand and optimize how people use and interact with technology

Avoid reliance on memory Use forcing functions Avoid reliance on vigilance Simplify key processes Standardize work processes Design systems with feedback and monitoring

mechanisms

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First Loop: Human-Machine System

Display

Controls

SensorySystem

MotorSystem

BrainComplexSystem

Human Machine

Interface 335

Human Factors Engineering / Ergonomics Mitigates and reduces errors in multiple high

reliability organizations (HRO) Predicts and provides an understanding of

human performance in complex environments Discovers underlying systemic factors that lead

to error Provides a framework for medical device

evaluation Identifies areas to improve patient safety

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High Reliability Organizations: Strong HFE Applications Nuclear Power Plants Air Traffic Controller Flight Deck on an Aircraft Carrier

Crew Resource Management Space Shuttle Hospitals

Emergency Departments Operating Rooms Intensive Care Units Centralized Telemetry Units

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HFE: Causal Factors

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Device Limitations

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Manipulated Display Design Variables

Location: Color Dimensionality: planar/perspective Motion: motion/stationary Intensity: dim/bright Coding: physical dimensions (size,shape) Modality: visual/auditory Content: information & structure

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Four (4) Categories of Display Design Principles1. Perceptual Consideration

• Avoid absolute judgment requirements, e.g. identification of specific sound level

• Support top down processing• Exploit redundancy gain• Maximize discriminability

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Four (4) Categories of Display Design Principles

2. Mental Model Consideration• Pictorial realism, e.g. orientation• Movement compatibility, e.g. direction• Ecological consistency

3. Attention Consideration• Minimize information processing cost• Proximity Compatibility (spatial compatibility)• Multi-channel processing

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Four (4) Categories of Display Design Principles

4. Memory Consideration• Support prediction• Exploit knowledge in the world, reduce

demands for knowledge in the head. E.g. recognition.

• Ensure consistency

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Stimulus-Response Compatibility

Compatibility between displayed information and method of response or control

Static sense: Compatibility between a display location and the location of the response

Dynamic sense: Compatibility between display movement and movement involved in the response

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Locational Compatibility

We have natural tendency to move or orient towards source of stimulation in environment—infants will orient to new pictures, new faces

Put the controls where the displays are – users want to move towards the source of stimulation

So why not put the control and the display in the same location? colocation principle

A touch screen takes this idea to the limit Elevator buttons Can’t always do that so, put controls right next to

displays (as close as possible)

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Stovetops Revisited

More compatible mappings between stimulus display and response means fewer mental operations, transformations from display to response

Norman called “natural mappings”

Co-location Poor compatibility348

Organizing S-R Compatibility

S-R Compatibility

Static Dynamic

Colocation(Locational

Compatibility)

Congruence MovementCompatibility

MovementProximity

Rules (Simplicity) or Stereotypes can be used to improve static or

dynamic compatibility

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Movement Compatibility

Compatibility in the dynamic sense: Compatibility between display movement

and movement involved in the response Typically movement of the control should

correspond to the movement in the display

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Movement Compatibility

Sometimes this can’t be done for practical reasons, however

There are common ways to show an increase: move a control up, to the right, forward, or clockwise

These types of common conventions are called population stereotypes

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Movement Proximity (Warrick’s principle)

Place moving control close to moving display

Principle of movement proximity

Better than:

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Errors Reason’s representation of the

relationship between decision errors, and the final unsafe acts--which produce local triggers via mediating factors

Mediating factors may be thought of as resident pathogens

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Use of Human Capabilities

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Vision / Visual

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Auditory

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Cognition vs. Perception

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Human Information Processing Model

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Environmental Factors

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Culture

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HFE Techniques

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Failure Mode and Effect Analysis

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Failure Mode and Effect Analysis (FMEA)

Is a tool for preventing failures. It is a way to identify the failures, causes, effects, and risks within a design or process and eliminate or reduce them.

Is a procedure for developing new designs or processes. Is the diary (documented evidence) of the design, the process

and the service. Is a systematic way of evaluating, tracking, and updating

designs and process development. Is a team-based approach.

- Palady, P. (1998) -

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5 Elements of an FMEA

1 Planning the FMEA

2 Failure Modes Effects Causes

3 Occurrence Severity Detection

4 Interpretation

5 The Follow Through

- Palady, P. (1998) -

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5 Elements of an FMEA

1. Planning the FMEA

2. Investigating the Failure Modes, Effects, and Causes

3. Determining the Occurrence, Severity, and Detection

4. Interpretation the FMEA

5. The Follow Through

- Palady, P. (1998) -

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1. Planning the FMEA

Planning the FMEA involves selecting the FMEA project and the team composition.

Select a project that has the greatest potential for quality payback to the company and its customers.

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2. Investigating the Failure Modes, Effects, and Causes

We should ask ourselves these 3 questions,

How could it fail? (Failure Mode) Why does it fail? (Causes) What happens when it fails? (Effects)

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3. Quantifying Severity, Occurrence, and Detection

We will use a rating scales to quantify severity, occurrence, and detection.

As a general rule, when rating the Occurrence, Severity, and Detection in FMEA, the bigger numbers are bad and the small numbers are good.

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4. Interpreting the FMEA

There are two common ways of analyzing and interpreting the FMEA. These are the:

Risk Priority Numbers (RPN)Area Chart

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5. The Follow Through

FMEA requires applications of other supporting quality tools. Some of these tools are Control Charting (SPC) and Design of Experiment (DOE).

Data must be analyzed using statistical methods at each step of the FMEA.

Little or no benefits can be expected from the FMEA without follow through.

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Benefits of FMEA

Cost savings: development cost Identification of safety concern for validation Serve as a guide for more efficient test

planning Improve customer satisfaction Track design changes and provide updates.

- Palady, P. (1998) -

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Benefits of FMEA

Minimize engineering changes Minimize unforeseen events or uncertainties

when designing or validating a process Minimize unnecessary controls in the process

- Palady, P. (1998) -

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Definitions

Failure is the inability of a design or process to perform based on its function. This is usually referred to as the problem, error, concern or challenge.

Potential Failures are failures that can happen on the design or process when being used by our customer.

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Definitions

Potential Effect are outcomes from potential failures which can either be mild or severe when the customer interacts with the potential failures of the product.

Failure Mode is the physical description of the manner in which an expected function is not achieved.

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Characteristics of a Failure Mode Each failure mode has potential effects.

These potential effects can lead to problems for our customers.

It is important to determine the root cause(s) of a failure mode. The root cause is the one that points the way toward preventive and/or corrective action of a failure mode.

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Examples of Failure Modes

Oversized/Undersized packaging Discoloring Misalign pin Seal leakage Wrong invoice Corroded material

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Identifying the Root Cause

The Levels of Causes represent a sequence of causes that leads to the failure mode. The lowest level is called the root cause.

Some failure modes will have fewer or more levels of causes. The important thing is to pursue the root cause.

Detailed investigation and analysis has to be performed on failure modes.

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Levels of causes of a failure mode using a flashlight as an example

Level 1 Level 2 Level 3

Failure Mode First Level Cause Root Cause

A Flashlight did not light

Light Bulb is not

working

Filament inside the bulb is broken

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Identification of Failure Mode As an exercise, let us enumerate the potential failure modes of an ordinary ballpoint pen and identify its possible root cause(s) and effects. Potential Failures : Ink blots

Possible Root causes of failure: Ink is too wet

Ink cartridge is defective

Ball point is too loose

Possible Effects: Dirty and ruin things

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Determining the Severity, Occurrence, and Detection.

Severity is evaluated based on the effect of the failure mode to the customer.

Occurrence is evaluated based on how often a failure mode or its cause happens.

Detection refers to the chance of catching the problem before we give it to the customer.

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Severity

This is a rating indicating the seriousness of the effect of the potential failure mode

There is a direct correlation between effect and severity

- Stamatis, D.H. (1995) -

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Occurrence

This is also referred to “Frequency”. This is the rating value corresponding to the

estimated number of frequencies and/or cumulative number of failures that could occur for a given cause over the life of the design / over a given quantity of parts produced with the existing controls.

- Stamatis, D.H. (1995) - 382

Detection

This is the rating corresponding to the likelihood that the proposed design controls / current process controls will detect a specific root cause of a failure mode before the part is released for production / the part leaves the manufacturing area.

- Stamatis, D.H. (1995) -

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Quantifying Severity, Occurrence, and Detection

We will use a rating scale from 1 to 10 to quantify severity, occurrence, and detection.

As a general rule, when rating the Occurrence, Severity, and Detection in FMEA, the bigger numbers are bad and the small numbers are good.

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Severity Scale

Rating Criteria: A failure could…

10 Injure a customer or employee

9 Be illegal

8 Render the product or service unfit for use

7 Cause extreme customer dissatisfaction

6 Result in partial malfunction

5 Cause a loss of performance likely to result in a complaint

4 Cause minor performance loss

3 Cause a minor nuisance; can be overcome with no loss

2 Be unnoticed; minor effect on performance

1 Be unnoticed and not affect the performance

Bad

Good

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Occurrence Scale

Rating Time Period Probability

10 More than once per day 30%

9 Once every 3–4 days 30%

8 Once per week 5%

7 Once per month 1%

6 Once every 3 months .03%

5 Once every 6 months 1 per 10,000

4 Once per year 6 per 100,000

3 Once every 1 – 3 years 6 per million

2 Once every 3 –6 years 3 per 10 million

1 Once every 6 –100 years 2 per billion

Bad

Good

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Detection ScaleRating Definition

10 Defect caused by failure is not detectable

9 Occasional units are checked for defects

8 Units are systematically sampled and inspected

7 All units are manually inspected

6 Manual inspection with mistake-proofing modifications

5 Process is monitored (SPC) and manually inspected

4 SPC used with an immediate reaction to out of control conditions

3 SPC as above with 100% inspection surrounding out of control conditions

2 All units are automatically inspected

Bad

Good

1 Defect is obvious and can be kept from affecting customer

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Twelve Basic Items in an FMEA Worksheet Heading Parts or Process Failure Modes Effects Causes Controls

Severity Occurrence Detection RPN Recommendations Status

Design FMEA WorksheetDFMEA Analysis

Project: _____________________ Team : _____________________

Date ___________ (original) ___________ (revised)

Item or Component

Potential Failure Mode

Potential Effect (s) of Failure

Potential Cause(s)

Current Controls R

PN Recommended

Action

Responsibility and

Target Date Action Taken

Sev

erity

Occ

urre

nce

Det

ectio

n

RP

N

“After”

Sev

erity

Occ

urre

nce

Det

ectio

n

Total Risk Priority Number = “After” Risk Priority Number =

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DFMEA Analysis

Project: _____________________Team: _____________________Date ___________ (original)

___________ (revised)

Item or Process

Step

Potential Failure Mode

Potential Effect (s) of Failure

Potential Cause(s)

Current Controls R

PN Recommended Action

Responsibility and

Target Date Action Taken Sev

erity

Occ

urre

nce

Det

ectio

n

RP

N

“After”

Sev

erity

Occ

urre

nce

Det

ectio

n

FMEA is a “Three-for-One” Tool – FMEA is a “Three-for-One” Tool – Cause and Effect, Pareto, and Countermeasure Cause and Effect, Pareto, and Countermeasure

Matrix!Matrix!

Cause & Effect Analysis of

Design/Process Potential Failures

Cause & Effect Analysis of

Design/Process Potential Failures

Pareto Analysis – Failure Priorities

Pareto Analysis – Failure Priorities

Countermeasure Identification and

Impact Assessment

Countermeasure Identification and

Impact Assessment

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Pareto Chart

All causes do not contribute equally to

a potential failure mode.

Approximately 20% of the listed causes

contribute to approximately 80% of the failure mode

- Palady, P. (1998) -

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HFE Techniques

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Jacob Nielsen 10 Usability heuristics

1. Visibility of system status2. Match between system and the real world3. User control and freedom4. Consistency and standards5. Error prevention6. Recognition rather than recall7. Flexibility and efficiency of use8. Aesthetics and minimalist design9. Help users recognize, diagnose and recover from

errors10. Help and documentation

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Shneiderman 8 golden rules

Strive for consistency Enable frequent users to use shortcuts Offer informative feedback Design dialogue to yield closure Offer error prevention and simple error handling Permit easy reversal of actions Support internal locus of control Reduce STM load

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Conclusion

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Mini-Case

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Mini-Case: get a host hospital and do the following: Identify human factor issues in clinical

management: Hospital organizational Hospital information flow and handling Equipment procurement and vendor management Equipment and inventory control management

Use FMEA to analyze and resolve the human factor issues for each clinical management area

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Mini-Case: choose a biomedical equipment Identify and analyze the four design display

variables in the equipment Identify usability issues in the equipment by

using usability heuristics Make recommendations on the identified

issues or problems using usability heuristics

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Reference

Rani GebaraBeaumont Services Company3601 W. 13 Mile RdRoyal Oak, MI 48073Phone: 248-551-7324E-mail: rgebara@beaumontservices.com

FMEA book GET FROM OPAC

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