Failure Modes and Effects Analysis

Failure Modes and Effects Analysis or FMEA is a simple yet powerful engineering quality management technique that helps identify and counter weak points in the design or manufacture of products or the design and execution of processes. Its structured approach (summarized in Figure 7.1) has made it one of the most widely-used tools for developing quality designs, systems and services and it can be used to improve processes in any organization. Application of FMEA in healthcare typically identifies process components for improvement actions based upon relative ratings of their anticipated frequency and the severity of adverse effects or events.

Conducting an FMEA involves the team following a sequence of generic steps as summarized in Figure 7.2 and Table 7.1. The first step is to establish the context of the issue and this involves mapping the process so that the details of the process are readily apparent (process mapping has been discussed already in Chapter 5). Possible Failure Modes can then be identified within the process, each one of which represents a specific risk that is to be considered. The rating schemes for the likelihood and severity of a Failure Mode or risk are not standardized beyond the organization employing them. In the illustrative examples shown in Tables 7.2 and 7.3, we have used scales that go up to 10. Even though some organizations employ scales that only go up

Figure 7.2 A flow chart for performing a Failure Modes and Effects Analysis (FMEA).

to five, we believe that the greater dynamic range in assessments that these scales permit is advantageous in deciding which risks are to be tackled first, and in their prioritization. Multiplying these two rankings together gives the Criticality scores, which are the actual values used when discriminating between risks of greater or lesser overall importance. Because of this step of calculating Criticality scores, FMEA is sometimes referred to as Failure Modes, Effects and Criticality Analysis or FMECA.

Table 7.1 The generic steps involved in performing a Failure Modes and Effects Analysis (FMEA)

Procedural step

Explanation

Examine and map the process Identify Failure Modes Determine the Effects Identify Contributory Factors

Rate the likelihood and severity of each Failure Mode

Calculate the Criticality of each

Failure Mode (i.e. each risk) Identify any existing Controls

Prepare an Action Plan

Identify all the Functions that are expected to occur.

Identify any ways in which any of the Functions might go wrong.

Establish the consequences of each Failure Mode.

Identify the underlying causes for each Failure Mode (one or more RCAs might be required for this).

Estimate, using standardized rating schemes (see Tables 7.2 and 7.3), the frequency or likelihood of occurrence of each Failure Mode or Contributory Factor, and rank each Effect in terms of the possible severity of its consequences.

These values are calculated by multiplying the likelihood and severity ranks together.

Analyze the process map, identify any monitoring or detection systems, mitigation systems, etc, and assess their impact on the assigned Criticality scores.

Identify courses of action and establish how these actions will be assessed for impact upon the process.

Table 7.2 Suggested list of likelihood ratings for FMEA Failure Modes ("risks"). The real range that might be encountered is 1 to 9 because anything rated as impossible is not a real risk, and therefore irrelevant to the FMEA, and anything rated as 10 should never be encountered in a real-world situation

Table 7.2 Suggested list of likelihood ratings for FMEA Failure Modes ("risks"). The real range that might be encountered is 1 to 9 because anything rated as impossible is not a real risk, and therefore irrelevant to the FMEA, and anything rated as 10 should never be encountered in a real-world situation

Likelihood

Rating

Comments

G

Impossible

Can never happen, hence it is not a real risk.

1

Very unlikely

2

Unlikely

4

Possible

6

Likely

8

Very likely

1G

Certain

This circumstance should never exist in a real world situation.

Table 7.3 Suggested list of consequences of Failure Effects ("risks") in an FMEA. The real range that might be encountered is 1 to 10, although the ranking of a risk as 9 or 10 should only refer to Failure Modes that are assessed as very unlikely (see Table 7.2)

Consequence

Rating

Comments

G

None

Hence it cannot be considered a real risk.

1

Trivial

In reality, there is no measurable adverse risk.

2

Minimal

The effect is, in reality, more of a nuisance or inconvenience with no identifiable effect on patient care.

4

Minor

e.g. an adverse effect upon efficiency, but without any measurable effect on treatment outcome.

6

Serious

e.g. significant adverse effect upon a patient's treatment outcome.

8

Major

e.g. loss of embryos, OHSS," infection of patients or staff.

9

Extreme

e.g. loss of life, damage to facility.

1G

Catastrophic

e.g. loss of multiple lives, destruction of facility.

a OHSS Ovarian Hyperstimulation Syndrome a OHSS Ovarian Hyperstimulation Syndrome

A Risk Matrix is a tabulation of the scores for all the risks identified by an organization in a way that allows them to be deemed, according to a partitioning of the Criticality scores, as (for example) no risk, low risk, medium risk, significant risk or high risk. These classifications can then be used in prioritizing the identified risks for management.

In engineering, Pareto methodology is commonly used to identify the 20% of "significant risk" issues that cause 80% of the process variability (Hutchison, 1994), i.e. the most important Failure Modes to address. However, in biology this sort of relationship is not always apparent or easy to determine, and decisions are often based on experience; this is a significant part of the reason why an IVF lab needs to have a senior, experienced scientist acting as its Director.

The endpoint of the FMEA is the creation of an Action Plan which must then be implemented. It is vital that for each change that is instituted within the Action Plan there is a system for monitoring its effectiveness and efficacy - without this there will be no evidence of positive

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