Task Analysis: A Practical Approach in Medical Device Development

Examining “Task Analysis” Through the Example of Blood Pressure Measurement

Introduction and Definition

“Task analysis” is a systematic method for analyzing individual steps (tasks) within a business process to identify problems and discover opportunities for improvement. In this article, we explain the fundamental concepts of task analysis and its practical applications through the familiar example of blood pressure measurement. While the content includes specialized knowledge, we explain with concrete examples in a manner accessible to beginners.

Task analysis extends beyond a simple operational improvement methodology and plays a crucial role in the design and development stages of medical devices. Specifically, international standards such as ISO 13485 (Quality Management Systems for Medical Devices) and IEC 62366-1 (Usability Engineering of Medical Devices) recognize systematic analysis of user tasks when operating medical devices as an essential requirement for ensuring safety and efficacy.

Task Analysis Framework and Implementation Levels

Task analysis is conducted across three distinct levels. First, through qualitative observation and interview surveys, we understand the workflow in actual usage environments. Second, we decompose each task and clarify the standard sequence of execution and the cognitive and physical activities required at each step. Third, we systematically identify potential errors that may occur in each task and their root causes.

Decomposing Blood Pressure Measurement Tasks

Using blood pressure measurement as a concrete example, this operation consists of the following individual tasks: patient preparation (patient information confirmation, guidance toward a resting state, ensuring appropriate body position), confirmation of measurement environment (ambient sound, temperature, illumination), selection and preparation of measurement equipment (device operation verification, accessory confirmation), cuff placement (accurate positioning and appropriate compression), measurement execution, and result recording and reporting.

Error Analysis in Task Execution

Examination of potential errors in each task represents an important perspective in task analysis. For example, in “Task 4: Cuff Placement,” multiple error modes are anticipated. When a cuff is placed at an incorrect position—such as positioning it higher than the level of the heart or significantly lower—measurement values may exhibit clinically significant errors of approximately 5-10 mmHg. Additionally, if cuff compression is excessive, it may not only cause patient discomfort and pain but also alter the arterial compression state, compromising measurement accuracy. Conversely, insufficient compression leads to reduced measurement reliability. Furthermore, patient postural instability (body movement, conversation) is known to be a major factor in measurement error.

Root Cause Analysis of Human Error

The essential purpose of task analysis is to identify potential errors that may exist in individual tasks and to determine prevention and improvement strategies. From a medical safety perspective, it is important to understand human errors not as simple “operational mistakes” but as manifestations of systemic vulnerabilities inherent to the system.

This analytical approach is highly effective for investigating root causes of human error and significantly contributes to improving patient safety in healthcare settings. Specifically, when addressing the question “Why did someone commit this error?”, it becomes possible to conduct a comprehensive examination that extends beyond individual carelessness to include task design, environmental factors, educational training gaps, and equipment design issues.

Application to Medical Device Development

Through detailed analysis of errors in each task and methods for resolving them, we can provide direct insights that benefit staff training and optimization of operational efficiency. From a medical device manufacturer’s perspective, findings from task analysis are essential for new product development and improvement of existing products. Specifically, a key approach is to redesign operations prone to errors into designs that are more error-resistant.

For example, when a blood pressure monitor manufacturer identifies through task analysis that “cuff positioning errors occur frequently,” they may consider design modifications such as adding scale markings to the cuff or physically restricting the positions where the cuff can be placed. Design improvements based on task analysis should be directly integrated into the risk management process (ISO 14971) outlined in ISO 13485.

Additionally, IEC 62366-1 requires that usability validation (formative usability validation) of user interface design evaluate performance when actual users execute tasks in typical usage scenarios. Task analysis is positioned as a preparatory step to this validation testing, providing the rationale for determining what scenarios and evaluation items should be established.

Practical Framework for Task Analysis Implementation

When implementing task analysis, the following considerations are recommended. First, observation and interview studies should be conducted by multiple stakeholders (healthcare professionals, patient representatives, medical device designers, etc.) to ensure error identification from diverse perspectives. Second, observation should cover not only normal operational execution but also task execution under realistic stress factors such as time constraints, fatigue, and unexpected environmental changes. Third, extracted errors should be subject to quantitative evaluation of their occurrence frequency, severity, and detectability, rather than remaining merely descriptive.

Table 1: Task Analysis Implementation Framework

Process Step	Implementation Content	Related International Standards
1. User and Task Identification	Understanding all users and usage scenarios in actual use environments	IEC 62366-1
2. Task Decomposition	Subdividing each task based on cognitive and physical activities	ISO 13485
3. Error Mode Extraction	Identifying potential errors at each step	ISO 14971
4. Risk Assessment	Quantifying error occurrence frequency, severity, and detectability	ISO 14971
5. Improvement Strategy Planning	Proposing design and operational improvements to prevent errors	ISO 13485
6. Validation	Verifying the effectiveness of improvements with actual users	IEC 62366-1

Error Mode Analysis in Blood Pressure Measurement (FMEA Example)

Table 2: Failure Mode and Effects Analysis for Blood Pressure Measurement Tasks

Task	Error Mode	Anticipated Causes	Impact on Patient	Prevention Strategy
Cuff Placement Position	Placement at position higher than heart	Insufficient anatomical knowledge; Inadequate training	Measurement underestimation (5-10 mmHg reduction)	Addition of scale markings; Design limiting placement positions
Cuff Compression Level	Excessive compression	Misunderstanding of placement procedure; Equipment malfunction	Patient discomfort, measurement error	Compression level indicator; Automatic adjustment function
Patient Preparation	Inadequate resting state	Insufficient environmental preparation; Time constraints	Unstable measurement values	Preparation checklist; Standardized work procedures
Result Recording	Reading error	Poor display screen visibility; Fatigue-related inattention	Misinformation to healthcare providers	Digital recording systems; Automatic data transfer

Healthcare Industry Trends and Implementation Beyond 2025

The organizational restructuring planned for the healthcare industry beyond 2025 demands evidence-based improvements in working practices. Specifically, medical IT advancement, construction of medical safety culture, and operational efficiency improvements represent critical issues in Japanese healthcare policy. Task analysis enables extraction of problems and presentation of resolution strategies, positioning it as an important approach for smooth business execution within new organizational structures.

Furthermore, in the medical device manufacturing industry, the rapid expansion of Software as a Medical Device (SaMD) has made ensuring appropriate alignment between user task execution and device software functions an urgent challenge. Detailed user task analysis is essential for meeting the requirements of IEC 62304 (Medical Device Software Lifecycle Processes).

Practical Considerations for Task Analysis Implementation

Several key principles should guide the implementation of task analysis in practice. First, it is essential that observation and interview studies involve multiple stakeholders—including clinical professionals, patient representatives, and medical device designers—to ensure comprehensive error identification from diverse perspectives. Second, observation should encompass not only routine task execution under normal conditions but also performance under realistic operational stressors such as time pressure, physical fatigue, and unexpected environmental disruptions. Third, identified errors should undergo quantitative risk evaluation rather than remaining merely descriptive, with assessment of occurrence frequency, severity of potential harm, and the likelihood of detecting the error before patient impact.

Conclusion

The above represents the fundamental methodology and practical framework of task analysis. While specific details vary depending on business content and occupation, this explanation, though merely one example, contains insights applicable to many business areas and life domains. For readers in the medical device industry, task analysis serves as an indispensable tool for practically implementing international standard requirements such as ISO 13485, IEC 62366-1, and ISO 14971. We recommend immediate practical implementation by all readers within their respective fields.

We sincerely hope this article will contribute to improving patient safety and operational efficiency for our readers.