Infusion Pump Power Failure Alarm IEC 60601-2-24

[Michael_ME Engineer]

Based off my interpretation of clause 201.11.8.101.2, it requires a high priority alarm when both supply mains and the internal battery fails. This alarm shall last for a minimum of 3 minutes.

My question is, how are people meeting this requirement?

It seems to me that to satisfy this requirement there would need to be:

1. An indication that the external DC supply cable was plugged in (charger present)
2. A voltage monitor for the charger voltage input
3. A voltage monitor for the battery voltage (with a reliable threshold of battery fail)
4. A visual indication
5. An audible indication
6. A method of detecting malfunction of the monitor circuit
7. A means of powering this additional circuit such as a capacitor or additional battery

 

[Peter Selvey]

It might seem like overkill but this is a critical requirement. Bigger battery packs often fail in a way where they work for a bit but the voltage dies quickly, meaning there is no time for a low battery alarm. This has been a common cause of serious events including death if the infusion pump is delivering a critical drug. It was one of the problems behind the worldwide recall of 250,000 Baxter Colleague infusion pumps.

So, yes in practice this would mean a dedicated independent circuit for the situation, often powered by a smaller NiMH battery or a supercap with a simple piezo beeper type alarm and maybe a pulsed light to save on power. From memory the standard has relaxed requirements for this kind of power failure alarm.

The original designs had batteries that watched themselves, which did not always work - a good lesson on why independence is important in safety designs.

 

[sivasuryan]

Hi Peter,
Can you provide me information where exactly the standard had relaxed requirement (so that we can use simple beeper type buzzer) for this kind of power failure alarm. can you recollect it from memory.

Thanks and regards,
R.Sivasuryan