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Risk Analysis Techniques 77

Unlike the FTA, Mind Maps do not use logic gates. Implicitly all connections are
OR gates. For example, in Figure 12.4 under “VF not detected,” it can happen if
either “SW doesn’t detect VF” OR “Sensing signal path is disrupted.”

12.2.3 Methodology
Step 1. Obtain the System requirements and architectural design. Understand the
theory of System operation.
Step 2. List the top undesired events for the System. These could be the Harms,
or the Hazardous Situations.
Step 3. Define the scope of analysis. What’s in; what’s out.
Step 4. For each top undesired event create a Mind Map. Brainstorm and identify
pathways to the top event.

Tip Although a Mind Map doesn’t model logic gates and the connections are interpreted as
OR gates, a work-around would be to create a node called “AND” where multiple branches feed
into it. The output of the AND node would occur if all the incoming branches occur.

12.3 PRELIMINARY HAZARD ANALYSIS

12.3.1 Introduction
PHA is a technique that can be used early in the development process to identify the
Hazards, Hazardous Situations, and events that can cause Harm when few of the
details of the medical device design are known. The PHA can often be a precursor to
further studies.
With the advance knowledge that is generated by the PHA, it becomes possible to
identify the safety-critical parts of the System concept, estimate the potential risks
associated with the System, and thus guide the design team to prioritize and focus
resources on the highest risk parts of the System.
Performance of a PHA is far more effective when people from various functions
are engaged to participate. This provides for a multiperspective analysis leveraging
insights from many points of view. Here, risk management can serve as a tool for
stimulation of communication among the team members who would ordinarily not
have reason to communicate.
R&D engineering benefits from the advance knowledge generated by the
PHA to anticipate Risk Controls and design them into the System early, instead
of late in the product development process and thus reduce product development
costs.
Another significant benefit of the PHA is that it can provide advisory to manage-
ment not to proceed with the development of a product, in case it is anticipated that