"Basic Safety" versus "Essential Performance"

Mark Meer

Trusted Information Resource
I'm presently struggling with the difference between "basic safety" and "essential performance" as defined in the IEC 60601-1:2005 standard.

The definitions from the standard are:

3.10 BASIC SAFETY freedom from unacceptable RISK directly caused by physical HAZARDS when ME EQUIPMENT is used under NORMAL CONDITION and SINGLE FAULT CONDITION

3.27 ESSENTIAL PERFORMANCE performance necessary to achieve freedom from unacceptable RISK

The two seem very similar to me. In another thread it was stated that "electrical stuff" is considered basic safety and not essential performance. But from the definitions, it seems like the performance of say, a fuse, might meet the definition of EP.

Can anyone help me put these two concepts into perspective? Some examples of things that would fall into one category and not the other (and why) would be very helpful....
 

Marcelo

Inactive Registered Visitor
re: "Basic Safety" versus "Essential Performance"

The definition from the Amendment makes things more clear:

ESSENTIAL PERFORMANCE
performance of a clinical function, other than that related to BASIC SAFETY, where loss or degradation beyond the limits specified by the MANUFACTURER results in an unacceptable RISK
NOTE ESSENTIAL PERFORMANCE is most easily understood by considering whether its absence or degradation would result in an unacceptable RISK.
 

Marcelo

Inactive Registered Visitor
re: "Basic Safety" versus "Essential Performance"

There?s also some examples in the rationale.
 

Mark Meer

Trusted Information Resource
re: "Basic Safety" versus "Essential Performance"

Ok. So let's I've got this right...to generalize:

Essential Performance relates to overall device features/functions, whereas the performance of things at the component-level (e.g. fuses) would be considered basic safety characteristics?
 

Marcelo

Inactive Registered Visitor
re: "Basic Safety" versus "Essential Performance"

Essential Performance relates to overall device features/functions, whereas the performance of things at the component-level (e.g. fuses) would be considered basic safety characteristics?

No, Essential Performance is related to clinical features/functions only. Basic safety is all the rest.

The concept is that, although usually safety and performance are separate things, in the case of some medical devices, some performance may lead to unacceptable risk and thus is directly linked to safety.
 

Mark Meer

Trusted Information Resource
re: "Basic Safety" versus "Essential Performance"

So, to clarify: by "clinical features/functions" do you mean those functions purely necessary for the device's intended use?

So, for example, a device function that is strictly a safety feature (e.g. a low-battery alarm) would NOT be considered essential performance, because the intended use ("clinical functions") could still be achieved in its absence?
 

Marcelo

Inactive Registered Visitor
re: "Basic Safety" versus "Essential Performance"

So, to clarify: by "clinical features/functions" do you mean those functions purely necessary for the device's intended use?

So, for example, a device function that is strictly a safety feature (e.g. a low-battery alarm) would NOT be considered essential performance, because the intended use ("clinical functions") could still be achieved in its absence?

The operation of a low-battery alarm can be essential performance if it?s incorrect operation leads to unacceptable risk.

It?s exemplified in the standard by this:

correct operation of an ALARM SYSTEM in an intensive care or operating room monitoring system where an incorrect/missing ALARM SIGNAL could lead to an incorrect response by the medical staff that would present an unacceptable RISK to the PATIENT; or

So, it?s not the one?s purely related to intended use, but device performance in general related to the clinical/intended use.
 

J0anne

Joanne
re: "Basic Safety" versus "Essential Performance"

Here's another explanation if you're not quite sure:

[FONT=&quot]1- [/FONT][FONT=&quot]Make a list of all the performance requirements of the device; and[/FONT]
[FONT=&quot]
[/FONT]

[FONT=&quot]2- [/FONT][FONT=&quot] For each function associated with performance, determine whether any variation in operation could cause harm. ? Where variation of performance could cause harm, this is identified as essential performance. [/FONT]
 

Peter Selvey

Leader
Super Moderator
re: "Basic Safety" versus "Essential Performance"

A key difference is the use of the word "direct" in the definition for basic safety.

Historically, IEC 60601-1 (1st and 2nd edition) defined safety as relating to direct harm. Examples were electric shock, mechanical injury, burns, ionizing radiation etc that come directly out of the equipment. Direct harm also includes functional parameters of higher risk devices when significantly out of control, such as surgical lasers, infusion pumps, dialysis, ESUs and X-ray, and special issues such as air infusion, bolus or blood loss from a detached blood circuit.

Indirect harm, typically related to misdiagnosis or performance out of spec but not directly harmful was not strictly under the scope of 601, although it slowly found it's way into the series via particular standards and arguably some of the requirements in 601 such as the need to declare the accuracy of indicated measurements.

The 3rd edition changed the definition of a safety hazard and removed the word "direct".

The standard has retained the concept of "direct" through the definition of "basic safety". The rational explains this is harm "incidental" to the main function, which although in many cases is good for a rough guide, it is not strictly correct according to the definition.

As with the second edition, direct harm can also be caused by the main function of the device, if this is a high risk function which is out of control, such as a surgical laser set to give a 10W 0.1ms pulse, which fails and outputs 100W continuously, burning a hole through the patient.

As most compliance criteria refers to both basic safety and essential performance, the distinction is not really a problem.

The main areas where it could have an impact are:
- Clause 4.3, which requires the manufacturer to list essential performance in the risk management file, and
- Clause 7.9.3.1 which requires the manufacturer to declare the essential performance in the technical manual (amendment 1 only)

Amendment 1 has also made it clear essential performance is to be considered in both normal and fault condition. This sets an overlap between the definition which needs to be addressed.

For example, in the case of an infant incubator, in normal condition we might expected the temperature control accuracy to +/-0.5C, while in SFC the temperature shall not exceed 39C. The normal condition is clearly essential performance. But the SFC falls under definition of basic safety, since it relates to physical harm directly arising from the equipment, and as such can be formally excluded from essential performance. But many would expect this to be included in the list of essential performance, and also declared under 7.9.3.1 (A1).

As for the design and testing, there is no effect, it just a matter of words in the risk management file and technical manual.
 
S

Shelley2018

re: "Basic Safety" versus "Essential Performance"

Hi Peter,

I'm digging this thread back up as I was hoping to get additional insight into the criteria regarding EP. In subclause 4.3 of Ed 3.1, the assessment process tends to flow in this sequence:
1. Identify Intended Use
2. Identify the clinical functions and the associated performance
3. Establish performance limits for these functions
4. Assess patient risk/impact of loss or failure of the device to perform within the limits specified
4.1 Take into consideration expected measures as per accompanying documents, including aspects such as serving and back-up medical care measures.
5. Now evaluate the risk compared with acceptability criteria. At this point if risk is unacceptable, then the function is deemed as EP.
6. Apply risk controls as required to achieve acceptable risk (effectively, follow ISO 14971).

My question is in relation to "taking credit" for the expected measures before making the final decision on whether risk is acceptable or not. Does this include aspects such as expected hospital protocols e.g. independent monitoring, hospital service intervals?

Also, these are controls in themselves. What are the expectations regarding verification of these pre-determined controls e.g. labeling has a warning to have independent monitoring and potential for evidence to be supplied to ensure that this is in fact taking place, or is "expected" to take place.

Thanks in advance for your help.
 
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