Re: Classification of Medical Device with Partial Compliance with a particular standa
The scope of IEC 60601-2-25:2011 now clearly states that "cardiac monitors covered by IEC 60601-2-27 [are excluded] where not intended for obtaining ECG REPORTS for diagnostic purposes".
Previously, IEC 60601-2-51 did apply to a patient monitor if there was an arrhythmia interpretation function, which many patient monitors had (e.g. to trigger alarms).
However in the new edition (IEC 60601-2-25, which replaces IEC 60601-2-51), the interpretation section is removed. I don't know why, maybe they plan a separate standard. So without that there is not much justification to apply to a patient monitor which is intended primarily to detect the heart rate.
There are a couple of catches: first is many monitors include a "diagnostic" filter with 0.05Hz ~ 150Hz. If this is included, this could be a reasonable justification for applying IEC 60601-2-25.
Also, some patient monitors include a function to monitor the ST segment. Again, this could trigger the application of IEC 60601-2-25.
The good news is, if there are no automated measurements made and displayed (e.g. QRS amplitudes, durations) then it is really similar to IEC 60601-2-27, just with tighter limits (e.g. 5% for sensitivity, instead of 20%). And that's quite reasonable as well - a limit of 5% makes much more sense than 20% if diagnostic decisions are being made based on the ECG record, and 5% is easily achievable with modern technology.