Start with functions
Primary functions express the principal clinical or operational purposes of the device. Supporting functions enable operation but are not necessarily primary. Classification should be based on product intent rather than organisational ownership or technical complexity.
Identify essential performance through risk
Performance is essential when its absence or degradation beyond defined limits would result in unacceptable risk. This conclusion therefore needs a traceable risk-management rationale and measurable performance limits.
- Identify the performance function.
- Define the degradation or loss condition.
- Determine the resulting sequence of events and hazardous situation.
- Evaluate whether the resulting risk is unacceptable.
- Establish measurable limits and verification evidence.
Turn conclusions into requirements
Essential-performance conclusions need to flow into architecture, alarms, fault response, environmental limits, test conditions and acceptance criteria. A label in a table is not itself a control.
Key takeaways
- Not every primary function is essential performance.
- Essential performance is a risk-based conclusion, not a marketing claim.
- Performance limits must be measurable and traceable into verification.
This article provides general educational information. Applicable requirements depend on the device, jurisdiction, lifecycle stage and current regulatory position.