Lecture 7: Incorporating Human Factors Engineering into Clinical Management
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
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
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
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
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
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)
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
Human Machine Display Sensory System Complex System Brain Motor System Controls Interface First Loop: Human-Machine System
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
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
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
Four (4) Categories of Display Design Principles • Perceptual Consideration • Avoid absolute judgment requirements, e.g. identification of specific sound level • Support top down processing • Exploit redundancy gain • Maximize discriminability
Four (4) Categories of Display Design Principles • Mental Model Consideration • Pictorial realism, e.g. orientation • Movement compatibility, e.g. direction • Ecological consistency • Attention Consideration • Minimize information processing cost • Proximity Compatibility (spatial compatibility) • Multi-channel processing
Four (4) Categories of Display Design Principles • Memory Consideration • Support prediction • Exploit knowledge in the world, reduce demands for knowledge in the head. E.g. recognition. • Ensure consistency
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
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)
Stovetops Revisited • More compatible mappings between stimulus display and response means fewer mental operations, transformations from display to response • Norman called “natural mappings” Poor compatibility Co-location
Rules (Simplicity) or Stereotypes can be used to improve static or dynamic compatibility Organizing S-R Compatibility S-R Compatibility Dynamic Static Movement Proximity Colocation (Locational Compatibility) Movement Compatibility Congruence
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
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
Movement Proximity (Warrick’s principle) • Place moving control close to moving display • Principle of movement proximity Better than:
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 Errors
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) -
1 Planning the FMEA 2 Failure Modes Effects Causes 3 Occurrence Severity Detection 4 Interpretation 5 The Follow Through 5 Elements of an FMEA - Palady, P. (1998) -
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) -
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.
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)
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.
4. Interpreting the FMEA There are two common ways of analyzing and interpreting the FMEA. These are the: • Risk Priority Numbers (RPN) • Area Chart
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.
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) -
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) -
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.
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.
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.
Examples of Failure Modes • Oversized/Undersized packaging • Discoloring • Misalign pin • Seal leakage • Wrong invoice • Corroded material