Safety Risk Management for Medical Devices

Citation

Elahi, B. (2022). Safety Risk Management for Medical Devices (2nd ed.). Academic Press (Elsevier).

Chapter Summary

The second edition has forty-one numbered chapters and four appendices. The publisher says it teaches safety risk management methodologies for medical devices compliant with ISO 14971:2019, and that it focuses exclusively on the safety risk assessment practices required in the MedTech sector. This edition adds coverage of ISO 14971:2019 and ISO/TR 24971, and of the history of risk management, the lifetime of a medical device, risk management review, production and post-production activities and post-market risk management. The chapters are grouped below by function.

Chapters 1–4: Introduction; What Is A Medical Device?; Why Do Risk-Management?; The Basics

The opening chapters set the scene: a history of risk management, the definition of a medical device, and the legal and regulatory, business, and moral and ethical reasons for risk management. Chapter 4 supplies the vocabulary of risk management (with reasonably foreseeable misuse), hazard theory, and systems and system types.

Chapters 5–8: Understanding Risk; Risk Management Standards; Requirements of the Risk Management Process; Quality Management System

Chapter 5 covers risk definitions, types of risk, contributors to risk, risk perception and risk computation. Chapters 6 to 8 then place the subject in its standards context: the origins of ISO 14971, harmonized standards, the risk management process and the quality management system.

Chapters 9–11: Usability Engineering and Risk Analysis; Biocompatibility and Risk Management; Influence of Security on Safety

Three topics that intersect with risk management. The usability chapter covers key terms, the user-device interaction model, use errors, environmental factors, design means to control usability risks, and task analysis.

Chapters 12–13: The BXM Method; Risk Management Process

Chapter 12 presents the BXM method (system decomposition, integration and quantitative risk estimation). Chapter 13 sets out the process itself: management responsibilities, the risk management file and plan, hazard identification, the clinical hazards list and the harms assessment list.

Chapter 14: Risk Analysis Techniques

The longest chapter by section count. It treats fault tree analysis, mind-map analysis, preliminary hazard analysis, and failure modes and effects analysis in depth: facilitation, hierarchical multi-level FMEA, failure theory, ground rules, criticality ranking, benefits and weaknesses, and ownership. It then separates design FMEA, process FMEA and use/misuse FMEA, the P-diagram, and a comparison of FTA and FMEA.

Chapters 15–16: Software Risk Management; Integration of Risk Analysis

Chapter 15 is about software: software types, software risk analysis and SFMEA, safety classification, risk controls, legacy software, software of unknown provenance, maintenance, reliability versus safety, and tips for safety-critical software. Chapter 16 integrates risk analysis across multi-level FMEAs and supplier input.

Chapters 17–21: Risk Estimation; Risk Controls; Verification of Risk Controls; On Testing; Risk Evaluation

The core analytical sequence. Estimation is qualitative, semi-quantitative or quantitative, with residual risks and risks that cannot be estimated. Risk controls include single-fault-safe design, risk control option analysis and information for safety. Verification covers implementation and effectiveness; the testing chapter covers risk-based sample size and attribute and variable testing; and evaluation applies risk acceptance criteria under each estimation method.

Chapters 22–24: Risk Assessment and Control Table (RACT); Benefit-Risk Analysis; Risk Management Review

The RACT workflow, benefit-risk analysis (including in clinical studies), and the risk management review that closes the pre-market process.

Chapters 25–28: Production and Post-Production Activities; Traceability; Lifetime of a Medical Device; Safety versus Reliability

Chapter 25 covers the regulatory basis and elements of post-market risk management: surveillance, post-market clinical follow-up, complaint handling and reports such as the PSUR, PMSR, MIR and MDR. Chapters 26 to 28 cover traceability, the device lifetime, and the relation between safety and reliability.

Chapters 29–37: Special cases, standards and process

Risk management for systems of systems, clinical investigations, legacy devices and combination devices (Chapters 29–32); basic safety and essential performance (33); the relationship between ISO 14971 and IEC 60601-1, ISO 10993-1, IEC 62366 and ISO 14155 (34); process metrics (35); the product development process (36); and suppliers (37).

Chapters 38–41: Axioms; Special Topics; Critical Thinking and Risk Management; Advice and Wisdom

The closing chapters step back from method: axioms, special topics (the conundrum, Cassandras, personal liability, creating a safety culture, predicting the future), critical thinking, and advice.

Appendices A–D

A glossary; templates for DFMEA, SFMEA, PFMEA, UMFMEA and the RACT; a worked example device, Vivio, with its product description and requirements, architecture, risk management plan, hazard lists, preliminary hazard analysis, DFMEA, PFMEA, UMFMEA, RACT and risk management report; and useful references.

Key Concepts

Chapters 1–13: Foundations and process

• Hazard, harm and risk: the vocabulary and hazard theory of Chapters 4 and 5.
• ISO 14971 risk management process: the requirements in Chapter 7 and the plan, file and hazard identification in Chapter 13.
• BXM method: the book's method for decomposing and estimating risk.

Chapters 14–24: Analysis, control and evaluation

• FMEA and fault tree analysis: the main risk analysis techniques of Chapter 14.
• Risk controls and their verification: how risks are reduced and shown to be reduced.
• RACT and benefit-risk analysis: how residual risk is summarised and judged.

Chapters 25–41: Life cycle and context

• Post-market risk management: surveillance and reporting after release.
• Interaction with other standards: IEC 60601-1, ISO 10993-1, IEC 62366 and ISO 14155.
• Safety culture: one of the special topics.

Critical Analysis

Strengths

• Built around the standard. The publisher stresses compliance with ISO 14971:2019 and ISO/TR 24971, and the chapters track the standard's process from hazard identification through control, evaluation and post-market activities.
• Practical tools and an example. Appendices supply templates for each FMEA type and the RACT, and a worked example device, Vivio, carries a risk management plan through to a risk management report.
• Wide reach across disciplines. Chapters on usability, biocompatibility, security, software and suppliers show how risk management crosses engineering specialisms.
• Author's practice. Elahi is a Technical Fellow at Medtronic, a contributor to ISO 14971 and a lecturer at Eindhoven University of Technology, Drexel University and Delft University of Technology.

Limitations

• Tied to the standards of its date. The book follows ISO 14971:2019 and was published in November 2021; later revisions of standards and regulations must be checked separately.
• Industry orientation. The publisher aims it at professionals in the MedTech sector, with graduate students as a secondary audience, so it is less a first course in design than a working reference.
• Many chapters. Forty-one chapters, several with long lists of subsections, mean a reader needs a route through the book, such as the one proposed below.

Where It Fits in the Course

Among the course's books, this is the specialist on safety risk. The Biodesign textbook is a process-oriented guide to inventing and bringing medical technologies to patients; Tranquillo, Goldberg and Allen's Biomedical Engineering Design walks student teams through designing a device; Ogrodnik's Medical Device Design is a practical introduction from need to market release; King, Fries and Johnson's Design of Biomedical Devices and Systems is a comprehensive guide to device development; and Teixeira's Design Controls for the Medical Device Industry is a reference on design control requirements under the FDA Quality System Regulation and ISO 13485:2016.

Read Elahi after a design text, when the question becomes how to show that a device is safe, and alongside Teixeira, since risk management feeds directly into design controls.

How to Use This Book

The book suits design, product, software, quality and regulatory engineers in the MedTech sector, and graduate-level students who are interested in medical devices. A prior course in device design or engineering design, and basic probability and reliability, are sensible preparation.

A practical plan:

• Core: Chapters 1 to 8 for context, then 13, 17 to 22 and 24 for the process from hazard identification to evaluation.
• Techniques: Chapter 14 when choosing between FTA, FMEA and PHA, and Chapter 15 for software products.
• Work through the example: read Appendix C (Vivio) beside the chapters and fill in the Appendix B templates for a device of your own.
• Later: Chapters 25 to 28 on post-market activities, and Chapters 29 to 41 as needed.