Medical devices directly impact patient health and safety. Ensuring they are intuitive, easy to operate, and error-tolerant requires a human-centered design approach that deeply understands user needs and limitations. Human factors engineering and usability testing methodically identify use risks and validate solutions.
In this section, we explore DeviceLab’s stepwise methodology to integrate user perspectives, mitigate use hazards, and confirm workflows through simulated environments and representative user studies. Detailed task analysis reveals the use of errors to resolve via improved interfaces and instructions. Formative tests uncover issues early, while summative studies validate user performance ahead of market release.
Thorough documentation captures activities and meets regulatory expectations around human factors, demonstrating due diligence to safe and efficient device use. When rigorously applied, the insights uncovered reduce adverse events, accelerate user adoption, and underpin product success across patient outcomes, customer loyalty, and business growth. Let’s dive into this step of the medical device development process.
Developing the User Evaluation (UE) Plan
A User Evaluation (UE) Plan provides the blueprint for human factors and usability efforts by defining goals, methods, timelines, resources, and regulatory alignment. As the first deliverable, it sets expectations for quantifying and improving device usability across the product lifecycle.
Establishing Plan Objectives
The UE Plan outlines the purpose and scope of planned human factors engineering activities based on device risk, novelty, complexity, and intended users. It identifies key questions to answer regarding safe and effective use. Stakeholder input helps prioritize assessments.
Defining Methodologies
The document details a portfolio of methodologies like heuristic evaluations, surveys, simulated use testing, focus groups, and control experiments to quantitatively and qualitatively gather user feedback. It describes participants, scenarios, data collection, tasks, and test protocols. Timelines coordinate with design milestones.
Regulatory Alignment
By benchmarking consensus standards like IEC 62366 and FDA guidance documents, the evaluation plan meets regulatory expectations for formative and summative assessments. This compliance focus helps ensure downstream submissions go smoothly.
A detailed UE Plan aligns human factors objectives, methods, timelines, and regulatory considerations to set initial expectations around confirming and enhancing medical device usability.
Creating the Use Specification
A use specification details how, where, why, and by whom the medical device will be used. Thoroughly characterizing the application environment, clinical context, user population, and workflows informs subsequent human factors efforts.
Documenting Intended Use
Intended use descriptions specify expected body contact sites, delivery mechanisms, dosage levels, operating principles, and target patient conditions. Documentation notes environments like hospitals, homes, or mobile emergency use and adjacent equipment.
Defining User Characteristics
Primary and secondary user groups define key characteristics like education, training, physical attributes, culture, and prior experience that shape needs and behaviors. Personas and user profiles help categorize clinicians, home users, patients, and maintenance technicians.
Outlining Use Scenarios
Typical usage scenarios walk through clinical applications, setup sequences, inputs, outputs, alerts, maintenance, and disassembly. Descriptions capture routine to complex interventions, noting steps prone to use errors based on historical data.
Robust use specifications provide the contextual backdrop for the user experience, guiding strategic human factors planning and design requirements.
Conducting Task Analysis
Task analysis breaks down required user interactions into stepwise sequences of cues, actions, and decisions to identify use risks. Documenting workflow steps and rating associated cognitive and physical demands spotlights complexity to reduce through design or training.
Deconstructing Workflows
Analysts work with users to map out every action across device setup, operation, monitoring, troubleshooting, maintenance, and teardown. Tasks decompose into subtasks detailing buttons pressed, switches toggled, choices made, and outputs interpreted to complete goals. Photos or videos capture flows.
Determining Critical Tasks
Within workflows, critical tasks directly impact patient safety if performed incorrectly. For example, inaccurate medication delivery settings, omitted sterilization steps, or misinterpreted sensor readings. Special attention targets mitigating risks for these tasks.
Assessing User Effort
Experts rate the cognitive skills, perceptual acuity, and physical strength demanded per task using standardized scales. High ratings prompt design simplification or better user guidance. Low ratings identify steps to potentially accelerate through greater automation.
Detailed task analysis provides a hierarchical understanding of usage workflows to streamline and safeguard the most crucial interactions impacting patients.
Performing Use Risk Assessment
Use risk assessments to systematically analyze identified tasks to uncover steps prone to user errors based on complexity, environmental factors, or user limitations. Quantified ratings help developers prioritize design and process changes to reduce patient hazards.
Pinpointing Use Error Opportunities
Analysts draw on prior experience using error checklists, focus groups, and new task analysis documentation to recognize where users may incorrectly perform operations, misinterpret feedback, or improperly maintain devices. Both inherent design issues and user training gaps contribute to errors.
Estimating Risk Severity and Likelihood
With potential use errors enumerated, standardized tables help rate both severity (potential patient harm) and probability for each based on the use specification context. Numerical scores produce risk priorities for mitigation.
Defining Mitigation Strategies
Highest priority use risks guide targeted design improvements, added alarms or confirmation steps, material changes, enhanced instructions or training, and supplementary labeling. The team documents residual risk levels and compares to acceptable criteria per standards. Hazards deemed tolerable based on benefit versus full mitigation receive special justification.
Detailed use risk assessments identify the most likely and impactful use errors to rectify through purposeful design and process changes, reducing patient harm.
Defining User Interface Requirements
User interface requirements codify identified needs and use risk mitigations in detailed design criteria to optimize ergonomics, simplicity, consistency, feedback, and error tolerance. Requirements align with regulatory guidelines to inform medical device screens, controls, labeling, accessories, and instructions.
Translating Needs into Requirements
Key inputs like use specifications, task analysis findings, user feedback, and risk assessment outputs feed concrete user interface specifications. Examples span desired button shapes, force thresholds, display resolutions, font sizes, icon designs, alert types, dial spacing, labeling content, and setup accessory specifications to support safe interactions.
Regulatory Alignment
Criteria reference relevant standard guidance on human-device interfaces and presentation of information to ensure compliance. For example, ISO 62366 is used for usability, and IEC 60601 is used for medical electrical equipment labels and instructions, which are applied across multiple device types. Traceability links standards to requirements.
Requirements Documentation
The full list provides specific, testable benchmarks for design reviews and verification against drawings, prototypes, or product samples. Links to their origin sources facilitate ongoing maintenance and compliance evidence. The living document evolves as insight deepens.
Robust user interface requirements directly apply usability insights to optimize medical device form and function for patient needs and risk mitigation while meeting standards.
Conducting Formative Usability Studies
Formative usability studies evaluate early device prototypes in representative user scenarios to uncover opportunities to optimize workflows, interactions, and overall experience. Open-ended feedback guides design iteration without rigid pass/fail criteria expected later in summative testing.
Informing Design Improvements
The formative focus is to gather honest qualitative feedback on what works well versus areas needing improvement in the user interface or workflow. Study tasks, surveys, and interview techniques probe satisfaction, ease of use, areas of confusion, and desired new features after hands-on device exposure.
Simulated Use Environments
To best assess real-world human factors, participants receive background training appropriate to their user profile before attempting typical tasks in inpatient, outpatient, or home settings replicated in a simulated laboratory. Controlled scenarios balance authentic cues with data collection needs.
Analyzing and Applying Insights
Detailed results analysis summarizes key findings, recurring themes, severity assessments, and recommendations to resolve problems through redesign. Additional user perspective helps determine which insights to prioritize when applying them to the next prototype iteration, targeting usability flaws and optimization opportunities.
Formative usability testing provides invaluable qualitative feedback from representative users to identify and resolve use difficulties early while shaping designs to better meet needs.
Performing Pre-Summative Study
After formative-driven design changes, pre-summative usability testing verifies resolutions address earlier issues while confirming readiness for formal validation. Any lingering concerns get corrections to maximize chances of success before final human factors testing.
Confirming Issue Resolution
New rounds of trials with updated prototypes focus specifically on scenarios, tasks, and measures where formative tests uncovered usability challenges. Study participants from prior rounds provide comparative experiences with old versus new interfaces. Questionnaires and interviews probe whether interventions resolved issues.
Finalizing Summative Readiness
Across evaluation tasks, success measures assess effectiveness, efficiency, and user satisfaction metrics compared to predetermined acceptance criteria and benchmarks. The remaining shortfalls shape final adjustments to maximize conformance ahead of final validation.
Closing Open Issues
As the last chance ahead of submission testing, any awkward workflows, confusing displays, difficult controls, complex sequences needing simplification, or terminology causing hesitation undergo changes. Instructions gain clarity, warnings visibility, and label concision to support first-time users.
Pre-summative usability testing ensures formative feedback gets addressed, acceptance criteria seem reasonably achievable, and any subtle lingering issues receive correction before high-stakes summative validation.
Developing the User Interface Specification
The user interface specification comprehensively documents the medical device’s final form, presentation, controls, workflows, and accessories to guide manufacturing and usability validation. Visuals, descriptions, and interaction models codify a user experience meeting needs.
Documenting the User Interface
The specification captures display screens, information hierarchy, button shapes/sizes, control panel layouts, dial/slider formats, toggle mechanics, label content/placement, accessory forms, and environmental ergonomics through photos, schematics, and written narratives. It details software navigation flows.
Ensuring Alignment
Reviews verify conformance to interface requirements linked back to identified user needs, ergonomic principles, use error mitigations, and regulatory guidelines. Traceability gives downstream confidence in design coherence. Gaps prompt adjustments.
Supporting Production and Validation
With detailed documentation, manufacturers produce devices matching prototypes used in summative studies, enabling performance comparison. The frozen specification focuses validation on reproducing the documented experience rather than continued design shifts. Changes necessitate revalidation.
An exhaustive user interface specification captures an optimized design meeting stakeholder needs while providing a stable target for production and usability validation as the final step before market release.
Conducting the Summative Usability Study
Summative usability studies provide quantified evidence that representative users can successfully operate the medical device to complete critical tasks within acceptance criteria in simulated use environments. Rigorous validation aims to satisfy regulatory expectations for safety and effectiveness.
Study Design for Validation
Formal protocols model real-world scenarios for setup, operation, troubleshooting, cleaning, and maintenance, reflecting the documented user interface. Pass/fail metrics are set for effectiveness, efficiency, and satisfaction using benchmarked instruments. Appropriate user groups receive device and context training.
Executing and Documenting Studies
In controlled labs modeled after intended use settings, trained participants attempt prescribed tasks on production-equivalent devices while observers score performance and capture feedback. All results feed pre-defined data reports, including errors, assists required, and subjective perceptions on workflow and ease-of-use.
Analyzing and Reporting Outcomes
Pass/fail metrics determine overall validation success by critical tasks. Trends reveal use deficiencies requiring labeling clarifications or feature adjustments post-launch. Participant quotes substantiate perceptions. Formal reports structure analysis for regulatory filings seeking commercialization permits after any final modifications.
Summative validation through rigorous, controlled testing on intended user groups confirms devices are ready for market deployment based on safe, efficient, and satisfactory operation in representative environments matching those of patients and clinicians.
Compiling the Human Factors Engineering (HFE) Report
The human factors engineering report summarizes all activities demonstrating due diligence to safe, efficient medical device use, and meeting regulatory expectations. It compiles planning frameworks, and uses characterizations, assessments, study protocols, results analysis, and conclusions for submission.
Demonstrating Methodical User Focus
Following structured templates, HFE reports overview the user evaluation plan, use specification, task analysis, use risk assessments, interface requirements, and how insights guided design. Details on formative and summative study methodologies, protocols, participant demographics, scenarios, effectiveness metrics, and subjective feedback spotlight a rigorous methodology ensuring usability.
Compiling Validation Evidence
Summaries clearly convey key testing results and conclusions, highlighting performance against benchmarks for critical tasks. Tables consolidate quantitative findings and qualitative user quotes. The discussion addresses limitations and potential post-market use risks needing communications. Supporting documents append protocols, survey instruments, regulatory alignments, and contributor credentials.
Navigating Regulatory Approvals
Report content and formats meet consensus standards requirements so reviewers can readily process compliance. Pre-submission reviews help identify any missing information. Quick responses to regulator questions prevent delays, enabling timely approvals to reach patients needing applicable medical technologies.
Comprehensive human factors evidence instills regulator confidence in patient safety and medical device effectiveness when used by intended operator populations in simulated real-world contexts.
Human Factors and Usability
Rigorous human factors engineering and usability optimization are imperative to medical device success, given the impact on patient health and safety. Structured methodologies like those applied by DeviceLab reveal user needs, capture workflows, identify use risks, guide interface designs, and validate performance with representative groups under simulated conditions.
From initial evaluation plans through summative validation reporting, each activity produces insights improving usability and safety. Enhancing interfaces, instructions, accessories, and workflows to better match user capabilities and environments ultimately drives adoption, loyalty, and market expansion.
Most importantly, thoughtfully addressing human interactions, perceptions, errors, and limitations through purposeful testing and design creates reliable medical technologies that provide intended benefits without preventable harm. Robust validation evidence gives regulators confidence in approvals.
In the final installment ahead, we will outline DeviceLab’s process for executing regulatory compliance activities in alignment with these human factors efforts to efficiently bring optimized medical devices to market for patient benefit.
To learn more about how we can help make your medical device safer and more user-friendly, get in touch with DeviceLab today. Our team is here to guide you through every step of the process to ensure your device meets both user needs and regulatory standards.
