Amendment 1 to IEC 60601-1:2005 was released in July 2012 and is now starting to get some attention. It is already acceptable to use the standard in some markets, and many designers and test labs should be aware of the changes and may start to reference them to justify alternate solutions.
The basic statistics are:
- 118 pages (English)
- 67 pages of normative text
- ~260 changes
- 21 new requirements
- 63 modifications to requirements or tests
- 47 cases where risk management was deleted or made optional
- 19 corrections to requirements or test methods
- Remainder were reference updates, notes, editorial points or clarifications
- USD$310 for amendment only
- USD $810 for the consolidated edition (3.1)
This document covers some of the highlights, including an in-depth look at essential performance. A pdf version of this analysis is avaliable, which also includes a complete list of the changes on which the analysis is made.
Risk management has been tuned up and toned down: the general Clause 4.2 tries to makes it clear that for IEC 60601-1, the use of ISO 14971 is really about the specific technical issues, such as providing technical criteria for a specific test or justifying an alternate solution. Full assessment of ISO 14971 is not required, and post market area is specifically excluded. The standard also clearly states that an audit is not required to determine compliance.
Within the standard, the number of references to risk management have been reduced, with some cases of simply reverting back to the original 2nd edition requirements. In other places, the terminology used in risk management references has been corrected or made consistent.
Essential performance has quietly undergone some massive changes, but to understand the impact of the changes you need to look at several aspects together, and some lengthy discussion is warranted.
First, the standard requires that performance limits must be declared. In the past a manufacturer might just say “blood pump speed” is essential performance, but under Ed 3.1 a specification is also required e.g. “blood pump speed, range 50-600mL/min, accuracy ±10% or ±10mL of setting, averaged over 2 minutes, with arterial pressure ±150mmHg, venous pressure -100~+400mmHg, fluid temperature 30-45°C”.
Next, the manufacturer should consider separately essential performance in abnormal or fault conditions. For example under a hardware fault condition a blood pump may not be expected to provide flow with 10% accuracy, but it should still confidently stop the blood flow and generate a high priority alarm. Care is needed, as the definition of a single fault condition includes abnormal conditions, and many of these conditions occur at higher frequency than faults and therefore and require a special response. User errors, low batteries, power failure, use outside of specified ranges are all examples where special responses and risk controls may be required that are different to genuine fault condition. For example, even a low risk diagnostic device is expected to stop displaying measurements if the measurement is outside of the rated range or battery is too low for accurate measurement. Such risk controls are now also considered “essential performance”.
Essential performance must also be declared in the technical description. This is major change since it forces the manufacturer to declare essential performance in the commercial world, especially visible since most manufacturers incorporate the technical description in the operation manual. Until now, some manufacturers have declared there is no essential performance, to avoid requirements such as PEMS. But writing “this equipment has no essential performance” would raise the obvious question … what good then is the equipment?
Finally many of the tests which previously used basic safety or general risk now refer specifically to essential performance in the test criteria. In edition 3.0 of the general standard, the only test clause which specifically mentioned essential performance was the defibrillator proof tests. Now, essential performance is mentioned in the compliance criteria many times in Clauses 9, 11 and 15. These are stress tests including mechanical tests, spillage, sterilization and cleaning. The good news is that the standard makes it clear that functional tests are only applied if necessary. So if engineering judgment says that a particular test is unlikely to impact performance, there is no need to actually test performance.
While essential performance is dramatically improved there are still two areas the standard is weak on. First, there is no general clause which requires a base line of essential performance to be established. Typically, performance is first verified in detail under fairly narrow reference conditions (e.g. nominal mains supply, room 23±2°C, 40-60%RH, no particular stress conditions). Once this base line is established, performance is then re-considered under a range of stress conditions representing normal use (±10% supply voltage, room temperature 10-40°C, high/low humidity, IP tests, mechanical tests, cleaning test, and so on). Since there are many stress tests, we normally use engineering judgment to select which items of performance, if any, need to be re-checked, and also the extent of testing. But this selective approach relies on performance having been first established in the base-line reference condition, something which is currently missing from the general standard.
The second problem is the reference to essential performance in PEMS (Clause 14). Many low risk devices now have particular standards with essential performance. And since essential performance is used as a criteria for stress tests, the “no essential performance” approach is no longer reasonable. But the application of complex design controls for lower risk devices is also unreasonable, and conflicts with modern regulations. Under note 2, the committee implies that Clause 14 needs only to be applied to risk controls. A further useful clarification would be to refer to risk controls that respond to abnormal conditions. For example, in a low risk device, the low battery function might be subject to Clause 14, but the main measurement function should be excluded, even if considered “essential performance”. It would be great if the committee could work out a way to ensure consistent and reasonable application for this Clause.
Moving away from essential performance to other (more briefly discussed) highlights are:
Equipment marking requirements: contact information, serial number and date of manufacture are now required on the labeling, aligning with EU requirements. The serial number is of special note, since the method of marking method is often different to the main label, and may not be as durable.
Accessories are also required to marked with the same details (contact information, serial number, date of manufacturer). This also fits with EU requirements, provided that the accessory is placed on the market as a separate medical device. This may yield an effective differentiation between an “accessory” and a “detachable part”. The new requirement implies that accessories are detachable parts which are placed on the market (sold) separately, whereas detachable parts are always sold with the main equipment.
Both the instructions for use and the technical description must have a unique identifier (e.g. revision number, date of issue)
For defibrillator tests, any unused connectors must not allow access to defibrillator energy (effectively requires isolation between different parts, or special connectors which prevent access to the pins when not in use)
Mechanical tests for instability and mobile equipment (rough handling test) are modified (market feedback that found the tests to be impractical)
The previous 15W/900J exemption of secondary circuits from fire enclosure/fault testing has been expanded to 100VA/6000J if some special criteria are met. Since the criteria are easy to meet, it will greatly expand the areas of the equipment that does not need a fire enclosure or flame proof wiring; welcome news considering the huge environmental impact of flame retardants.
- For PEMS, selected references to IEC 62304 are now mandatory (Clauses 4.3, 5, 7, 8 and 9)
For a complete (unchecked) list of changes, including a brief description and a catergory of the type of change, please refer to the pdf version.
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